No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Lack of Long-Term Effect of Vitamin C Supplementation on Blood Pressure
Abstract
In a double-blinded randomized controlled trial, we investigated the long-term effect of vitamin C supplementation on blood pressure. A total of 439 Japanese subjects with atrophic gastritis initially participated in the trial using vitamin C and beta-carotene to prevent gastric cancer. Before and on early termination of beta-carotene supplementation, 134 subjects dropped out of this trial, whereas 120 and 124 subjects took the vitamin C supplement daily at either 50 mg or 500 mg, respectively, for 5 years. Before supplementation, neither systolic nor diastolic blood pressure was significantly related with the serum vitamin C concentration. This relationship was unchanged after adjustment for age, body mass index, and alcohol intake or after stratification by gender. After 5 years, systolic blood pressure significantly increased in groups, regardless of vitamin C dose, compared with baseline. Systolic blood pressure in the high-dose group (500 mg daily) increased from 125.4 to 131.7 mm Hg (5.88 mm Hg increase; 95% confidence interval [CI], 3.11 to 8.65). This value was similar with that of the low-dose group (5.73 mm Hg increase; 95% CI, 2.62 to 8.83) and of the dropout group (4.52 mm Hg increase; 95% CI, 1.26 to 7.77). There was no difference in change of diastolic blood pressure among the 3 groups. In conclusion, we observed no reduction in blood pressure with long-term moderate doses (500 mg/day) of vitamin C supplementation in a high-risk population for stomach cancer and stroke.
... With several implicated indices of health risk, the body mass index (BMI) is the mathematical ratio of weight (in kilogram) to height (in meters square) that can be linked with body composition or body fat percentage. According to the world health organisation, People with a BMI of 25 to 29.9 are considered overweight, while those with a BMI of 30+ are considered obesed [5]. The relationship between BMI and mortality has reportedly shown to vary with sex, age, cohort effects, socioeconomic status and ethnic background [6]. ...
... Based on systolic and diastolic values obtained (SBP and DBP), subjects were then classified as either hypertensive (SBP and DBP ≥ 140 and 90 mm Hg respectively) or normotensive (SBP and DBP < 140 and 90 mm Hg respectively). The decision to use above values as grouping standard was informed by recommendations of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure [14,5]. Worth mentioning is that this procedure was exclusively carried out by qualified nurses and physicians. ...
... Socioeconomic Status: A number of studies have also indicated a strong association between supplement use with higher income level (Kim et al., 2002). Studies by Lyle et al., (1998) and Kirk et al., (1999) showed that women who use supplements tend to have an income that is greater then the median United States income. ...
... Those who have higher income levels also seem to be more regular users of dietary supplements. This confirms the findings of some previous studies (Kim et al., 2002;Ishihara 2001;Greger, 2001;Johnson et al., 2000;Kirk, 1999 andLyle, 1998), which found that users of dietary supplement had higher income levels and social class. ...
This study provides a demographic and psychographic profile of Malaysian dietary supplement users. There were significant differences between regular and non-regular users were only noted in terms of age, marital status, number of children and personal income while there was no significant difference for other demographic variables. Six psychographic dimensions were identified. Regular users of dietary supplements could be considered as price conscious and brand triers. This study suggests some implications for marketers to think about when marketing dietary supplements.
... With several implicated indices of health risk, the body mass index (BMI) is the mathematical ratio of weight (in kilogram) to height (in meters square) that can be linked with body composition or body fat percentage. According to the world health organisation, People with a BMI of 25 to 29.9 are considered overweight, while those with a BMI of 30+ are considered obesed [5]. The relationship between BMI and mortality has reportedly shown to vary with sex, age, cohort effects, socioeconomic status and ethnic background [6]. ...
... Based on systolic and diastolic values obtained (SBP and DBP), subjects were then classified as either hypertensive (SBP and DBP ≥ 140 and 90 mm Hg respectively) or normotensive (SBP and DBP < 140 and 90 mm Hg respectively). The decision to use above values as grouping standard was informed by recommendations of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure [14,5]. Worth mentioning is that this procedure was exclusively carried out by qualified nurses and physicians. ...
... Although both lipo-soluble and hydro-soluble vitamins do not exert direct actions on cardiovascular function, these are considered to affect different cardiovascular diseases upon modulating their respective risk factors. However, their beneficial effects are inconclusive and particularly, the results of various clinical trials for the treatment of heart disease with different vitamins have been disappointing (Olson, 1973;Kushi et al., 1996;Palumbo et al., 2000;Yusuf et al., 2000;Pruthi et al., 2001;Kim et al., 2002;Myung et al., 2013;Ingles et al., 2020). Thus, in view of the uncertainty of demonstrated beneficial cardiovascular effects of different vitamins, the American Heart Association has recommended consumption of vitamin-rich fresh fruits and vegetables instead of vitamins supplements. ...
By virtue of their regulatory role in various metabolic and biosynthetic pathways for energy status and cellular integrity, both hydro-soluble and lipo-soluble vitamins are considered to be involved in maintaining cardiovascular function in health and disease. Deficiency of some vitamins such as vitamin A, B6, folic acid, C, D, and E has been shown to be associated with cardiovascular abnormalities whereas supplementation with these vitamins has been claimed to reduce cardiovascular risk for hypertension, atherosclerosis, myocardial ischemia, arrhythmias, and heart failure. However, the data from several experimental and clinical studies for the pathogenesis of cardiovascular disease due to vitamin deficiency as well as therapy due to different vitamins are conflicting. In this article, we have attempted to review the existing literature on the role of different vitamins in cardiovascular disease with respect to their deficiency and supplementation in addition to examining some issues regarding their involvement in heart disease. Although both epidemiological and observational studies have shown some merit in the use of different antioxidant vitamins for the treatment of cardiovascular disorders, the results are not conclusive. Furthermore, in view of the complexities in the mechanisms of different cardiovascular disorders, no apparent involvement of any particular vitamin was seen in any specific cardiovascular disease. On the other hand, we have reviewed the evidence that deficiency of vitamin B6 promoted KCl-induced Ca²⁺ entry and reduced ATP-induced Ca²⁺-entry in cardiomyocytes in addition to decreasing sarcolemmal (SL) ATP binding. The active metabolite of vitamin B6, pyridoxal 5′-phosphate, attenuated arrhythmias due to myocardial infarction (MI) as well as cardiac dysfunction and defects in the sarcoplasmic reticulum (SR) Ca²⁺-transport in the ischemic-reperfused hearts. These observations indicate that both deficiency of some vitamins as well as pretreatments with different vitamins showing antioxidant activity affect cardiac function, metabolism and cation transport, and support the view that antioxidant vitamins or their metabolites may be involved in the prevention rather than the therapy of cardiovascular disease.
... Neither systolic nor diastolic blood pressure was significantly related with the serum vitamin C concentration Kim et al., 2002 ...
Hypertension is a highly prevalent disease worldwide. It is known for being one of the most important risk factors for developing cardiovascular disease, including acute myocardial infarction and stroke. Therefore, during the last decades there have been multiple efforts to fully understand the mechanisms underlying hypertension, and then develop effective therapeutic interventions to attenuate the morbidity and mortality associated with this condition. In this regard, oxidative stress has been proposed as a key mechanistic mediator of hypertension, which is an imbalance between oxidant species and the antioxidant defense systems. A large amount of evidence supports the role of vascular wall as a major source of reactive oxygen species. These include the activation of enzymes, such as NADPH oxidase and xanthine oxidase, the uncoupling eNOS and mitochondrial dysfunction, having as a major product the superoxide anion. Among the stimuli that increase the production of oxidative species can be found the action of some vasoactive peptides, such as angiotensin II, endothelin-1 and urotensin II. The oxidative stress state generated leads to a decrease in the biodisponibility of nitric oxide and prostacyclin, key factors in maintaining the vascular tone. The knowledge of the mechanisms mentioned above has allowed generating some therapeutic strategies using antioxidants as antihypertensives with different results. Further studies are required to position antioxidants as key agents in the treatment of hypertension. The current review summarize evidence of the role of oxidative stress in hypertension, emphasizing in therapeutic targets that can be consider in antioxidant therapy.
© Georg Thieme Verlag KG Stuttgart · New York.
... β-carotene and vitamin E supplements also failed to lower the incidence of lung cancer among male smokers (The Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group, 1994). In a study with atrophic gastritis patients, daily consumption of vitamin C for 5 years was not effective in ameliorating high blood pressure (Kim et al., 2002). These observations raise the question do purified phytochemicals confer the same health benefits as they do in their naturally occurring forms? ...
Increasing incidence of chronic diseases in the 21st century has emphasized the importance of developing crops with enhanced nutritional value. Plant-based diets are associated with reduced incidence of many chronic diseases. The growing population and increased food demand have prioritized the development of high-yielding commercial crop varieties at the expense of natural flavors as well as health-benefiting compounds including polyphenols. Flavonoids are a large subfamily of polyphenols abundant in the plant kingdom with known health-promoting effects, making them a promising trait to be re-introduced into elite lines. Given the vast array of flavonoids and the complexity of plant food metabolome interactions, it is difficult to identify with certainty the specific class(es) of flavonoids in the food matrix that are anti-inflammatory. To address this, we have developed four maize near-isogenic lines (NILs); a line that lacked both anthocyanins and phlobaphenes, a second NIL containing phlobaphenes, a third line had anthocyanins, and a fourth line that contained both anthocyanins and phlobaphenes. The phytochemical profiles and the antioxidant potential of the NILs were characterized. The accumulation of anthocyanins and phlobaphenes contributed significantly to antioxidant capacity compared to maize lines that lacked one or both of the compounds (p < 0.05). Pilot study showed that intake of flavonoid-rich maize diets were able to alleviate experimental colitis in mice. These NILs offer novel materials combining anthocyanins and phlobaphenes and can be used as powerful tools to investigate the disease-preventive effects of specific flavonoid compound in diet/feeding experiments.
... In a consequent trial, 500 mg of vitamin C had no consequence on BP through 5 years of the traverse. In once-over, its leftovers dim whether an extended affirmation of vitamin C content reduces BP (Kim et al., 2002). ...
Hypertension is a global epidemic health problem with a huge impact and variation in prevalence across all geographical areas. Hypertension is a leading risk factor for cardiovascular disease, stroke, and chronic renal disease. The incidence of adult hypertension in low-and middle-income countries is far greater than wealthier countries. Moreover, hypertensive adults in developing countries are unable to receive adequate treatment as compared with those in developed countries. Thus, sustainable and local treatments are necessary for adults in low income countries. In this article we critically reviewed the impact of carrot and beetroot-based beverages to alleviate hypertension. The supplementation of carrot and beetroot-based beverages should be promoted as a key component of a healthy lifestyle to control blood pressure in healthy and hypertensive individuals. In conclusion, carrot and beetroot juices supplementation might be an easy, accessible, safe, and evidence-based strategy to alleviate hypertension. [Razzaq PA, Akram A, Tahir S, Ijaz A, Abedin ZU, Haq IU, Sarwar S, Akram M. A critical review: Carrot and beetroot-based beverages to alleviate hypertension. Life Sci J 2020;17(9):18-28].
... ( UPHS 1979) Studies have demonstrated a role of vitamin C in maintaining the normal production and biological activity of endothelium-derived nitric oxide which plays a role in vascular tone and reactivity. (Kim et al., 2002) Thus, plasma vitamin C levels should be investigated for its possible role in lowering or maintaining normal BP. We evaluated the levels of plasma Vitamin C level on the patients of both hypertensive and normotensive subjects. ...
The etiology of essential hypertension includes increased oxidative
stress. Vitamin C is one of the potent reducing agents and scavenger of
free radicals in biological systems. The role of benefit of vitamin C, an
antioxidant to antihypertensive therapy were studied along with MDA
level in comparison with control. It was found plasma ascorbic acid
concentration to be inversely associated with systolic and diastolic BP
in hypertensive subjects. A decrease in Vitamin C, an increase in
malondialdehyde levels were observed in hypertensive group as
compared to control. The increase in MDA and decrease in Vitamin C
were statistically significant. Vitamin C or ascorbic acid is an
antioxidant that may decrease the blood pressure (BP) and influence the
endothelial dysfunction.
... Antioxidant treatment with ascorbic acid was initially shown to lower blood pressure in a limited number of patients with hypertension [391,392]. However, larger studies have not found a clear beneficial effect of antioxidant vitamins on the development or control of blood pressure [393,394]. The combination of ascorbic acid and polyphenols actually resulted in a higher blood pressure variation [228]. ...
Hypertension is the most prevalent cause of cardiovascular disease and kidney failure, but only about 50% of patients achieve adequate blood pressure control, in part, due to inter-individual genetic variations in the response to antihypertensive medication. Significant strides have been made toward the understanding of the role of reactive oxygen species (ROS) in the regulation of the cardiovascular system. However, the role of ROS in human hypertension is still unclear. Polymorphisms of some genes involved in the regulation of ROS production are associated with hypertension, suggesting their potential influence on blood pressure control and response to antihypertensive medication. This review provides an update on the genes associated with the regulation of ROS production in hypertension and discusses the controversies on the use of antioxidants in the treatment of hypertension, including the antioxidant effects of antihypertensive drugs.
... For accurate measurements of blood pressure, qualified nurse or medical doctor were used. Precautionary measures were taken in order to achieve acceptable records [22,23] as follows: ii. The bladder encircled and covers two-third of the extent of the upper arm. ...
... In recent decades the possible antihypertensive effect of antioxidants has been investigated in humans in several studies, with conflicting results [7,[94][95][96][97]. This effect, attributed in the past mainly to vascular mechanisms such as restoration of NO-mediated vasodilation [7,98], could be at least in part a consequence of sympatho-inhibition achieved by antioxidants, as recently suggested also in humans [39]. ...
Background:
A high dietary intake of polyphenols has been associated with a reduced cardiovascular mortality, due to their antioxidant properties. However, growing evidence suggests that counteracting oxidative stress in cardiovascular disease might also reduce sympathetic nervous system overactivity.
Methods:
This article reviews the most commonly used techniques to measure sympathetic activity in humans; the role of sympathetic activation in the pathophysiology of cardiovascular diseases; current evidence demonstrating that oxidative stress is involved in the regulation of sympathetic activity and how antioxidants and polyphenols might counteract sympathetic overactivity, particularly focusing on preliminary data from human studies.
Results:
The main mechanisms by which polyphenols are cardioprotective are related to the improvement of vascular function and their anti-atherogenic effect. Furthermore, a blood pressure-lowering effect was consistently demonstrated in randomized controlled trials in humans, when the effect of flavonoid-rich foods, such as tea and chocolate, was tested. More recent studies suggest that inhibition of sympathetic overactivity might be one of the mechanisms by which these substances exert their cardioprotective effects. Indeed, an increased adrenergic traffic to the vasculature is a major mechanism of disease in a number of cardiovascular and extra-cardiac diseases, including hypertension, obesity and metabolic syndrome and heart failure. A considerable body of evidence, mostly from experimental studies, support the hypothesis that reactive oxygen species might exert sympatho-excitatory effects both at the central and at the peripheral level. Accordingly, supplementation with antioxidants might reduce adrenergic overdrive to the vasculature and blunt cardiovascular reactivity to stress.
Conclusions:
While supplementation with "classical" antioxidants such as ROS-scavengers has many limitations, increasing the intake of polyphenol-rich foods seems to be a promising novel therapeutic strategy to reduce the deleterious effects of increased adrenergic tone, particularly in essential hypertension.
... Our study hypothesized that decreasing − O 2 levels would have potential implications in the model studied. Several trials have been conducted to determine whether antioxidant treatment may reduce BP, but the results are conflicting [24][25][26] . Extracellular SOD, the first-line endogenous defense, is normally present in living tissues and converts − O 2 to hydrogen peroxide (H 2 O 2 ) that is degraded to water and molecular oxygen by CAT 27 . ...
There is evidence that diets rich in salt or simple sugars as fructose are associated with abnormalities in blood pressure regulation. However, the mechanisms underlying pathogenesis of salt- and fructose-induced kidney damage and/or consequent hypertension yet remain largely unexplored. Here, we tested the role of oxidative state as an essential factor along with high salt and fructose treatment in causing hypertension. Fischer male rats were supplemented with a high-fructose diet (20% in water) for 20 weeks and maintained on high-salt diet (8%) associate in the last 10 weeks. Fructose-fed rats exhibited a salt-dependent hypertension accompanied by decrease in renal superoxide dismutase activity, which is the first footprint of antioxidant inactivation by reactive oxygen species (ROS). Metabolic changes and the hypertensive effect of the combined fructose-salt diet (20 weeks) were markedly reversed by a superoxide scavenger, Tempol (10 mg/kg, gavage); moreover, Tempol (50 mM) potentially reduced ROS production and abolished nuclear factor-kappa B (NF-κB) activation in human embryonic kidney HEK293 cells incubated with L-fructose (30 mM) and NaCl (500 mosmol/kg added). Taken together, our data suggested a possible role of oxygen radicals and ROS-induced activation of NF-κB in the fructose- and salt-induced hypertension associated with the progression of the renal disease.
... mmHg, p = 0.005) and 6.04 mmHg lower DBP (95% CI 2.70-9.38 mmHg, p = 0.0002) than those in the lowest level of plasma ascorbic acid. Kim et al. (2002) organized a double blinded RCT to investigate the long-term effect of vitamin C supplementation on BP; two groups were supplemented with 50 or 500 mg vitamin C for 5 years in Japan. Before supplementation, neither SBP nor DBP was significantly related with the serum vitamin C concentration. ...
Obesity means the accumulation of excessive fat that may interfere with the maintenance of optimal state of health. Obesity causes cardiac and vascular disease through well-known mediators such as hypertension, type-2 diabetes mellitus, and dyslipidemia, but there are evidences for other mediators such as chronic inflammation, oxidative stress, and thrombosis. The decreased levels of antioxidants factors and nitric oxide predispose to further cardiovascular adverse events. To reduce the risks, antioxidants can help by neutralizing the free radicals and protecting from damage by donating electrons. Having the capacity, vitamin C protects from oxidative stress, prevention of non-enzymatic glycosylation of proteins, and enhances arterial dilation through its effect on nitric oxide release. It also decreases lipid peroxidation, and alleviates inflammation. The anti-inflammatory property of vitamin C could be attributed to ability to modulate the NF-kB DNA binding activity and down-regulation in the hepatic mRNA expression for the interleukins and tumor factors.
... It is worth mentioning that an earlier RCT found that 50-500 mg/day of vitamin C had no effect on BP in the long term. 165 In this trial, 244 subjects supplemented with vitamin C for 5 years, and in both groups BP increased significantly. Furthermore, there was no difference in BP between the treatment groups and the control (dropout) group. ...
Objective: We conducted a comprehensive review of the most current data available on the antihypertensive effects of 29 different nutraceuticals.
Design: In this review, we collected evidence from clinical trials and meta-analyses of clinical trials with human subjects that are representative of the general adult population; studies of infants, children, and pregnant women were excluded. Observational studies were included in some cases as supplementary evidence, and in vitro or animal studies were included only for the purpose of explaining hypotensive mechanisms. PubMed served as the primary search engine.
Outcome measures: The efficacy of each nutrient and botanical was demonstrated by a treatment that resulted in a reduction of either systolic or diastolic blood pressure in humans.
Results: All of the reviewed botanical and nutrient supplements, with the exception of French maritime pine bark extract and maitake ( Grifola frondosa), have been demonstrated to effectively lower blood pressure in humans with good tolerability.
Conclusions: Current data supporting the use of nutrients and botanicals in the treatment of blood pressure are encouraging.
... 46 In hypertensive subjects, a few small trials initially showed benefit, 47,48 but, later large clinical trials, including the SU.VI.MAX study, showed no improvement in blood pressure with antioxidant therapy. 49,50 Surprisingly, large doses of beta-carotene, vitamin A, and vitamin E have paradoxically worsened cardiovascular outcomes in some studies. 51,52 The failure of antioxidants in humans might reflect the low rate constant of vitamins such as E and C with superoxide and related ROS, the inability to target subcellular sites in which ROS are formed, and that some ROS have beneficial effects. ...
It has become clear that reactive oxygen species (ROS) contribute to the development of hypertension via myriad effects. ROS are essential for normal cell function; however, they mediate pathologic changes in the brain, the kidney, and blood vessels that contribute to the genesis of chronic hypertension. There is also emerging evidence that ROS contribute to immune activation in hypertension. This article discusses these events and how they coordinate to contribute to hypertension and its consequent end-organ damage.
... Several small randomized, placebo-controlled trials have revealed short term beneficial effects of vitamin C, including significantly reduced BP and improved endothelium dependent vasodilatation [43,44]. Conversely, a large clinical trial assessing long term effects (5-years) of vitamin C supplementation in 244 subjects has failed to prove the BP-lowering effect of vitamins C in initially normotensive subjects [45]. A few short term (8 weeks) studies examining synergistic effects of vitamin C and E have confirmed beneficial effects on BP reduction and vascular function in newly discovered hypertensive patients [46,47]. ...
Background/aims:
Hypertensive patients present with increased oxidative stress and frequently receive angiotensin II (ANGII) receptor type I blockers (ARB) for blood pressure (BP) reduction. Recent studies revealed an important role of ANGII in maintaining vascular oxidative homeostasis, including sustaining normal sodium dismutase activity. This study aimed to investigate the effects of antihypertensive therapy and also vitamin C/E supplementation on BP, oxidative stress and endothelial activation in patients with essential hypertension.
Methods:
Newly discovered patients received ARB/olmesartan or the Ca2+-channel blocker (CCB)/amlodipine, and additionally vitamin C/E or placebo throughout weeks 9-16. ELISA was used to determine 8-iso-prostaglendin F2-alpha (8iPGF2α) and endothelial activation markers.
Results:
In both groups BP was normalized during first 8 weeks of therapy. Vitamins C/E had no additional BP-lowering effect. The vitamins C/E supplementation was not effective in reducing absolute values of 8iPGF2α; however; the magnitude of 8iPGF2α reduction was significantly greater in patients taking vitamins C/E in the CCB group. Although plasma 8iPGF2α positively correlated to BP, a significant decrease occurred during an additional 8 weeks of treatment. There were no changes in endothelial activation markers related to the specific action of ARB or CCB.
Conclusions:
Present study suggests that observed oxidative stress is a consequence of hypertension. BP reduction is associated with the observed decrease in oxidative stress and changes in endothelial activation regardless of antihypertensive therapy.
... In recent decades the possible antihypertensive effect of antioxidants has been investigated in several studies, with conflicting results (Duffy et al., 1999;Fotherby et al., 2000;Kim et al., 2002;Ward et al., 2004;Hooper et al., 2008). This effect, attributed in the past mainly to vascular mechanisms such as restoration of NO-mediated vasodilation (Taddei et al., 1998;Hooper et al., 2008), could be at least in part a consequence of sympatho-inhibition achieved by antioxidants, as recently suggested also in humans (Bruno et al., 2012a). ...
... mmHg. 85 In contrast, administration of 500 mg of vitamin C for 5 years had no effect on BP. 86 In conclusion, the association between vitamin C and controlling BP remains unclear due to the inconsistent results observed among research studies. Many minerals are involved in controlling BP levels; among them the major minerals positively involved in BP regulation are potassium, magnesium, and calcium. ...
Gut microbiota play a significant role in host metabolic processes, and recent metagenomic surveys have revealed that they are involved in host immune modulation and influence host development and physiology (organ development). Initially, probiotics are identified as potential therapeutics to treat gastrointestinal disorders and to revitalize the disturbed gut ecosystem. Currently, studies are exploring the potential for expanded uses of probiotics for improving the health conditions in metabolic disorders that increase the risk of developing cardiovascular diseases such as hypertension. Further investigations are required to evaluate targeted and effective use of the wide variety of probiotic strains in various metabolic disorders to improve the overall health status of the host. This review addresses the causes of hypertension and the hypotensive effect of probiotics, with a focus on their mechanistic action.
... The administration of long term moderate doses (500mg/day) of vitamin C supplementation among patients with atrophic gastritis did not lead to a 52 reduction in blood pressure. However, a meta-analysis of the short-term effect of vitamin C on blood pressure revealed that taking an average of 500mg/day for 8 weeks led to a reduction in systolic and diastolic blood pressures of -3.84 mm Hg (95% CI: -5.29 to -2.38 mm Hg; p < 0.01) and -1.48 mm Hg (95% CI: -2.86 to -0.10 53 mm Hg; p = 0.04), respectively. ...
... A systematic review of cross-sectional studies reported an inverse association between vitamin C intake and BP, 46 whereas clinical trials show inconsistent results. 47,48 Our study has several strengths. First, we used data from a large nationally representative sample and usual dietary intakes of sodium and potassium, which could warrant generalizability. ...
The association between dietary sodium and potassium, the ratio of sodium to potassium, and blood pressure remains unclear.
We evaluated the associations between blood pressure and dietary sodium and potassium intake in terms of the amount and ratio in Korean adults.
This cross-sectional study was based on data from the fourth and fifth Korean National Health and Nutrition Examination Survey, 2007-2012.
A total of 24,096 adults (aged ≥19 years) without history of antihypertensive medication use were selected. The 24-hour recall method was used for dietary assessment. We categorized the subjects into four groups using median intakes of sodium and potassium, and defined the low sodium/high potassium intake group as the reference group.
High blood pressure (HBP) was defined as mean systolic or diastolic blood pressures of ≥140 or ≥90 mm Hg, respectively.
Multivariate logistic regression was performed to estimate the odds ratio and 95% CI to investigate the association between the four groups of sodium and potassium intakes and HBP.
Sodium intake was positively associated with diastolic blood pressure, with an increase of 0.21 mm Hg per 1 mg/kcal increase in sodium (P<0.001). In contrast, potassium intake was negatively associated with systolic blood pressure, with a decrease of 1.01 mm Hg per 1 mg/kcal increase in potassium (P<0.001). After adjusting for confounders, the high sodium/low potassium (odds ratio 1.21, 95% CI 1.02 to 1.44) and low sodium/low potassium intake groups (odds ratio 1.19, 95% CI 1.01 to 1.40) were at higher risk of HBP than the reference group. The risk of HBP in the high sodium/high potassium group did not differ from that in the reference group.
Low potassium intake was associated with an increased risk of hypertension. These results suggest that increasing potassium intake might be beneficial for hypertension control among populations with low-potassium diets.
Copyright © 2015 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.
... 10,11 In hypertensive humans, although a few small studies have shown benefit, 12,13 larger trials have failed to confirm an effect of antioxidant vitamins on either the development or control of blood pressure. 14,15 The results of these clinical trials have raised questions and doubt about the oxidation theory of disease. One clear message is that, as mentioned here, the role of ROS is far more complex than simply one of causing pathology. ...
... Kim et al observed no change in blood pressure after vitamin C supplementation. [27] Palumbo et al [28] also could not show the reduction in blood pressure after vitamin E supplementation whereas according to KS Meera et al, vitamin C has shown to improve endothelium dependent vasodilatation in hypertensives and increase in nitric oxide bioavailability . Vitamin C influences blood pressure probably by its free radical scavenging property and preventing prostacyclin synthase inhibition. ...
... Although vitamins C and E can protect LDL from oxidation (45,46), it is possible that this substantial increase in plasma LDL resulted in abundance of substrate that exceeded this protective mechanism. An effect of antioxidants such as vitamin C and E on BP is not consistently observed (23,47,48) and was not observed in our study, nor did it interfere with our results. PRA was similar among the groups, as common in chronic untreated, experimental renovascular hypertension (4,5,18). ...
Atherosclerotic renovascular disease (RVD) amplifies damage in a stenotic kidney by inducing pro-inflammatory mechanisms and disrupting tissue remodeling. Oxidative stress is increased in RVD, but its direct contribution to renal injury has not been fully established. The authors hypothesized that chronic antioxidant intervention in RVD would improve renal function and attenuate tissue injury. Single-kidney hemodynamics and function at baseline and during vasoactive challenge were quantified using electron-beam computed tomography in pigs after 12 wk of experimental RVD (simulated by concurrent hypercholesterolemia and renal artery stenosis, n = 7), RVD daily supplemented with antioxidant vitamins C (1 g), and E (100 IU/kg) (RVD+Vitamins, n = 7), or controls (normal, n = 7). Renal tissue was studied ex vivo using Western blot analysis and immunohistochemistry. Basal renal blood flow (RBF) and glomerular filtration rate (GFR) were similarly decreased in the stenotic kidney of both RVD groups. RBF and GFR response to acetylcholine was blunted in RVD, but significantly improved in RVD+Vitamins (P < 0.05 versus RVD). RVD+Vitamins also showed increased renal expression of endothelial nitric oxide synthase (eNOS) and decreased expression of NAD(P)H-oxidase, nitrotyrosine, inducible-NOS, and NF-κB, suggesting decreased superoxide abundance and inflammation. Furthermore, decreased expression of pro-fibrotic factors in RVD+Vitamins was accompanied by augmented expression of extracellular (matrix metalloproteinase–2) and intracellular (ubiquitin) protein degradation systems, resulting in significantly attenuated glomerulosclerosis and renal fibrosis. In conclusion, chronic antioxidant intervention in early experimental RVD improved renal functional responses, enhanced tissue remodeling, and decreased structural injury. This study supports critical pathogenic contribution of increased oxidative stress to renal injury and scarring in RVD and suggests a role for antioxidant strategies in preserving the atherosclerotic and ischemic kidney.
... Despite this evidence, other estimates of the causal association between L-ascorbic acid and cardiometabolic health were not consistent (17)(18)(19)(20)(21)(22). A long-term RCT of vitamin supplementation on the prevention of CVD in .14,500 ...
Observational studies showed that circulating l-ascorbic acid (vitamin C) is inversely associated with cardiometabolic traits. However, these studies were susceptible to confounding and reverse causation.
We assessed the relation between l-ascorbic acid and 10 cardiometabolic traits by using a single nucleotide polymorphism in the solute carrier family 23 member 1 (SLC23A1) gene (rs33972313) associated with circulating l-ascorbic acid concentrations. The observed association between rs33972313 and cardiometabolic outcomes was compared with that expected given the rs33972313-l-ascorbic acid and l-ascorbic acid-outcome associations.
A meta-analysis was performed in the following 5 independent studies: the British Women's Heart and Health Study (n = 1833), the MIDSPAN study (n = 1138), the Ten Towns study (n = 1324), the British Regional Heart Study (n = 2521), and the European Prospective Investigation into Cancer (n = 3737).
With the use of a meta-analysis of observational estimates, inverse associations were shown between l-ascorbic acid and systolic blood pressure, triglycerides, and the waist-hip ratio [the strongest of which was the waist-hip ratio (-0.13-SD change; 95% CI: -0.20-, -0.07-SD change; P = 0.0001) per SD increase in l-ascorbic acid], and a positive association was shown with high-density lipoprotein (HDL) cholesterol. The variation at rs33972313 was associated with a 0.18-SD (95% CI: 0.10-, 0.25-SD; P = 3.34 × 10(-6)) increase in l-ascorbic acid per effect allele. There was no evidence of a relation between the variation at rs33972313 and any cardiometabolic outcome. Although observed estimates were not statistically different from expected associations between rs33972313 and cardiometabolic outcomes, estimates for low-density lipoprotein cholesterol, HDL cholesterol, triglycerides, glucose, and body mass index were in the opposite direction to those expected.
The nature of the genetic association exploited in this study led to limited statistical application, but despite this, when all cardiometabolic traits were assessed, there was no evidence of any trend supporting a protective role of l-ascorbic acid. In the context of existing work, these results add to the suggestion that observational relations between l-ascorbic acid and cardiometabolic health may be attributable to confounding and reverse causation.
... Sin embargo, existen otros autores que no han encontrado beneficios con la administración de antioxidantes en la terapéutica de la HTA 73,74 . Hay aspectos que deben tenerse en cuenta, y que no han sido correctamente evaluados en todos los estudios sobre el uso de antioxidantes en este escenario, lo que explica la existencia de resultados tan diversos. ...
Salt-sensitive hypertension is produced by a decrease in salt renal excretion after a salt overload. Over the last few years, a new theory has been developed to explain this condition based on renal tissue inflammation. This process begins with free radicals production in renal tissue due to oxidative metabolism. Then they favor a renal inflammation mechanism with T-lymphocytes infiltration and other immune cells. Essentially, T-lymphocytes determine an increase in angiotensin ii production which raises sodium and water retention. Association among autoimmune diseases and hypertension may be explained, in part, by the relationship between salt-sensitive hypertension and renal inflammation. The use of antioxidant drugs and the development of new medicaments may be a choice for treating patients affected with this condition.
Copyright © 2013 Instituto Nacional de Cardiología Ignacio Chávez. Published by Masson Doyma México S.A. All rights reserved.
... 19 In another study, 500 mg/day of vitamin C treatment had no effect on blood pressure over the course of 5 years. 20 It remains uncertain whether an increased intake of vitamin C reduces blood pressure. ...
Hypertension affects one in three adults in Turkey and the United States. Only half are treated for this condition and only 10–20% is controlled. Dietary modifications such as salt restriction, moderation of alcohol drinking, and a diet rich in fruits, vegetables, and legumes and low in snacks, sweets, meat, and saturated fat are helpful in the treatment of hypertension. Consumption of dark chocolate is also associated with a drop in systolic blood pressure. Individual dietary factors that may reduce blood pressure include increased intakes of potassium, calcium, fish oil, fiber, and milk-based and vegetable-based protein.
Results from randomised controlled trials (RCTs) testing the effect of vitamin C supplementation on blood pressure (BP) have been inconsistent. This systematic review evaluated the effects of vitamin C supplementation on BP and included RCTs testing the effects of vitamin C supplementation alone, on systolic and diastolic BP in adult participants (≥18 years). Random-effect models were conducted to estimate the pooled effects of vitamin C supplementation on BP. A total of 20 studies with 890 participants were included. The median dose of vitamin C was 757.5 mg/d, the median duration was 6 weeks. Vitamin C supplementation was found to reduce systolic BP by -3.0 mmHg (95%CI: -4.7, -1.3 mmHg; p = 0.001). Subgroup analysis showed a more pronounced effect on systolic BP in patients with hypertension (-3.2 mmHg, 95%CI -5.2, -1.2 mmHg, p = 0.002) and diabetes (-4.6 mmHg, 95%CI -8.9, -0.3 mmHg, p = 0.03). Further research needs to evaluate the long-term effect of vitamin C on BP in populations with impaired cardio-metabolic health.
This study was designed to investigate effects of the Vitamin C and cashew on biochemical parameters that include concentrations of Uric acid and Creatine phosphokinase, (60) sample of blood have collected and they have divided for 4 groups (2 Control Group C1 ,C2 No treated) Group1( G1) Vitamin C 500 mg/day Group2( G2) Cashew (Anacardium occidentale) 100 g / day The results of this study showed that the physical stress and oxidative stress resulted by acute exercise which caused a significant increase in concentration of serum Uric acid and CPK, while Given the Vitamin C, cashew to period 15 day it is given alone Group. The results a significant decrease in concentration of serum Uric acid and CPK in males for control group, The results showed decrease in Uric acid with Vitamin C (3.50±0.69) for control group (6.64±1.40) and with cashew (4.41±0.94) for control group (6.16±1.34) While results of CPK record decrease in the group treated with Vitamin C (59.9±21.4) comparison with control (83.8±28.5) and with cashew (42.1±12.8) for control group (76.1±22.8) The above results reveals an important of the Vitamin C and Cashew like a strong antioxidant and removing the effects of the free radicals and decreasing the oxidative stress in which the soccer for it during the acute exercise.
Scurvy is one of the oldest diseases in human history. Nowadays, although scurvy tends to become a forgotten disease in developed country, rare cases still occur, especially in people undergoing extreme diet, old people or children with poor diet and patients with malabsorption.
In this Research, Biblical verses dealing with the scurvy are described. The history, the importance of vitamin C, the characteristics of scurvy, the prevalence, the pediatric scurvy, scurvy in the adult individuals, the prevalence, and the management are examined.
The disease spectrum of scurvy includes dermatological, musculoskeletal, and systemic manifestations, including limping, hemorrhagic syndrome, arthritis, and weakness. Subperiosteal hematoma, ring epiphysis, metaphyseal white line, and rarefaction zone along with epiphyseal slips are common radiological findings. Because of the wide clinical spectrum (musculoskeletal complaints and/or mucocutaneous lesions or systemic symptoms), scurvy can mimic several conditions, including autoimmune diseases, infections, and neoplasia. While children may present anorexia, irritability, failure to thrive, limping or refusal to walk. Musculoskeletal revelations, mostly subperiosteal hematoma, are the main manifestation of scurvy in the pediatric population.
In the recent years, the diagnostic possibilities have been validated through scientific research and have shown medicinal value in the diagnostics and the management of conditions associated with the scurvy.
This research has shown that the awareness of the scurvy has accompanied human during the long years of our existence.
Cardiometabolic diseases (CMDs) are metabolic diseases (e.g., obesity, diabetes, atherosclerosis, rare genetic metabolic diseases, etc.) associated with cardiac pathologies. Pathophysiology of most CMDs involves increased production of reactive oxygen species and impaired antioxidant defense systems, resulting in cardiac oxidative stress (OxS). To alleviate OxS, various antioxidants have been investigated in several diseases with conflicting results. Here we review the effect of CMDs on cardiac redox homeostasis, the role of OxS in cardiac pathologies, as well as experimental and clinical data on the therapeutic potential of natural antioxidants (including resveratrol, quercetin, curcumin, vitamins A, C, and E, coenzyme Q10, etc.), synthetic antioxidants (including N-acetylcysteine, SOD mimetics, mitoTEMPO, SkQ1, etc.), and promoters of antioxidant enzymes in CMDs. As no antioxidant indicated for the prevention and/or treatment of CMDs has reached the market despite the large number of preclinical and clinical studies, a sizeable translational gap is evident in this field. Thus, we also highlight potential underlying factors that may contribute to the failure of translation of antioxidant therapies in CMDs.
Thirty six percent of people in USA and Canada regularly use complementary and alternative medicine (CAM) for the prevention and treatment of different diseases, including hypertension. Generally, majority of the hypertensive patients do not disclose the use of such remedies, and also health care providers do not usually ask their hypertensive patients if they use CAM. The widespread consumption of CAM in hypertension requires clear understanding of their underlying mechanism of action, efficacy and safety. This chapter will provide a comprehensive list of CAM commonly used by Americans for the prevention and treatment of hypertension as well as their postulated mechanism of action. Modulation of drug metabolizing enzymes and their safety will also be covered along with the clinical consequences, i.e. drug-herb or herb-disease interactions. patients and healthcare providers should also be careful with using CAM therapies, because not only is there minimal evidence that several CAM products work to treat hypertension, but their safety hasn't been well-established.
Introducción: la hipertensión arterial (HTA) es una de las mayores cargas de enfermedad y riesgo para infarto cardíaco, la insuficiencia cardíaca y el fallo renal. Se reconoce que el estrés oxidativo (EO) es un determinante en el desarrollo de complicaciones y el progreso de la HTA. Se determinó el índice de EO (IEO) en individuos con HTA y en un grupo sano control, para evaluar su posible correlación.
Materiales y métodos: se midió IEO en una población de 112 individuos con HTA de distintos grados entre 50 y 70 años escogidos al azar y se comparó con los valores de un grupo control de voluntarios sanos, con la intención de definir el grado de correlación entre los niveles del IEO y la severidad de HTA, mediante la medición de biomarcadores para el EO en lisado de eritrocitos.
Resultados: a pesar de que los beneficios de la terapia antioxidante (TAO) no han sido definitivamente probadas, en gran parte porque las enfermedades complejas no dependen de un solo componente fisiopatogénico, el EO sigue siendo una piedra angular en el desarrollo de complicaciones y el empeoramiento de los cuadros clínicos de muchos padecimientos. La demostración de biomarcardores específicos mejora la posibilidad de una TAO dirigida. El presente ensayo demostró que la edad, el género y la etnia no influyen en el IEO y que el EO fue severo en los casos de HTA III, moderado en HTA II y estuvo ausente en el subgrupo con HTA grado I.
Conclusiones: estos resultados sugieren una relación entre los niveles de EO y severidad de HTA y sustenta evidencias para diseñar nuevos ensayos clínicos que evalúen la eficacia de una TAO adyuvante en el manejo de la HTA.
Hypertension is considered as the most common risk factor for cardiovascular disease. Inflammatory processes link hypertension and cardiovascular disease, and participate in their pathophysiology. In recent years, there has been an increase in research focused on unraveling the role of inflammation and immune activation in development and maintenance of hypertension. Although inflammation is known to be associated with hypertension, whether inflammation is a cause or effect of hypertension remains to be elucidated. This review describes the recent studies that link inflammation and hypertension and demonstrate the involvement of oxidative stress and endothelial dysfunction—two of the key processes in the development of hypertension. Etiology of hypertension, including novel immune cell subtypes, cytokines, toll-like receptors, inflammasomes, and gut microbiome, found to be associated with inflammation and hypertension are summarized and discussed. Most recent findings in this field are presented with special emphasis on potential of anti-inflammatory drugs and statins for treatment of hypertension.
Cadmium (Cd) has been recognized as one of the most important environmental and industrial pollutants. This study investigated the impact of acute exposure to Cd on oxidative stress and the inflammatory marker interleukin-6 (IL-6) in the plasma of rats and the histological picture of liver and kidney, as well as to examine the potential protective effect of tetrahydrobiopterin (BH4).
Methods:
Rats were divided into control group, Cd group that received a single intraperitoneal (i.p.) dose of 4 mg/kg b.w. of CdCl2 and BH4+ Cd group that received a single dose of BH4 (20 mg/kg, i.p.) and subsequently exposed to a single dose of Cd 24 h after the BH4 treatment.
Results:
Cd increased the plasma levels of hepatic enzymes (ALT and AST), urea, creatinine, malondialdehyde (MDA), and IL-6 and decreased the superoxide dismutase (SOD) activity. Also, it induced histopathological alterations in the liver with severe degeneration, especially in centrilobular zones. Renal tubular epithelium showed vacuolated cytoplasm and dense nuclei. VEGF expression was mild. Ultrastuctural changes were seen in some renal tubules. The nuclei appeared distorted with electron dense chromatin. Mitochondria with destructed cristae were observed. BH4 pretreatment had protective effects, since it significantly reduced the levels of IL-6 and ameliorated the alteration in oxidative status biomarkers induced by Cd. Improvement of histopathological alterations was observed in Cd-groups. The nuclei were vesicular euchromatic, intact mitochondria and normal appearance of the filtration membrane. Moderate expression of VEGF was noted.
Conclusion:
This study has provided clear evidence for the protective efficacy of BH4 against experimental Cd toxicity.
Evidence for blood pressure-lowering effects of vitamin C (VC) supplementation in clinical trials is inconsistent and limited studies have examined the effect of VC supplementation on hypertension (HTN) control. In this study, eligible patients were cluster assigned to receive 300 mg VC per day or nothing for 6 months. During the 6-month follow-up period, a questionnaire survey was obtained and standardized blood pressure measurements were performed on all subjects. Oral administration of VC significantly decreased the diastolic blood pressure and pulse pressure with a significant increase in HTN control. After adjusting for confounding variables, treatment with VC was associated with ~ 0.5 risk reduction of uncontrolled HTN in subjects received anti-hypertensive medications, whereas lower indoor and outdoor and ground temperature were significantly associated with an increased risk of uncontrolled HTN in all patients. Our results warrant further studies investigating the mechanisms underlying the association between VC and HTN control.
Dans de ce travail nous avons étudié les relations entre adiposité globale et abdominale et risque cardiovasculaire: facteurs de risque, marqueurs intermédiaires du risque évalués par l'atteinte des gros troncs artériels et incidence des événements vasculaires ischémiques chez les adultes participant à l'étude SU.VI.MAX.(Supplémentation en Vitamines et Minéraux AntioXydants). Les analyses transversales ont détaillé les associations entre différents facteurs socio-démographiques et l'augmentation de l'adiposité. Le tour de taille (TT) était le seul marqueur anthropométrique à être associé à la fois avec des marqueurs écho graphiques d'athérosclérose carotidienne (épaisseur intima-média) et avec la rigidité artérielle (vitesse de l'onde de pouls). En considérant les anomalies du syndrome métabolique, la pression artérielle (PA) était le facteur le plus fortement associé à ces deux mêmes marqueurs artériels. Les analyses longitudinales ont montré que la variation du poids était positivement associée à celle de la PA et de la cholestérolémie. Cette relation n'était pas modifiée par la prise en compte d'une perte de poids intentionnelle. La combinaison d'une élévation du TT et du taux de triglycérides était un prédicteur des événements ischémiques. Ces résultats illustrent l'intérêt et les limites de l'utilisation de marqueurs anthropométriques simples de l'adiposité abdominale (TT) comme prédicteur du risque cardiovasculaire. Il apparaît également important de mieux comprendre l'effet des fluctuations pondérales sur ce risque.
Background:
Thiol/disulphide homeostasis plays a critical role in numerous intracellular enzymatic pathways including antioxidant defense and detoxification. This study was designed to investigate the impact of thiol/disulfide homeostasis in adolescent patients with recently diagnosed primary hypertension (HT) using a novel and automated method.
Methods:
Native thiol/disulphide levels were measured by a novel spectrophotometric method (Cobasc 501, Roche Diagnostics, Mannheim, Germany) in 30 patients with primary HT together with 30 healthy controls.
Results:
The levels of native thiol, total thiol, and native thiol/total thiol ratios were significantly lower, while the disulphide level, disulphide/native thiol, and disulphide/total thiol ratios were significantly higher in patients with primary HT compared with the control group. There were significant positive correlations between 24-h mean systolic and diastolic blood pressure and disulphide levels, disulphide/native thiol, and disulphide/total thiol ratios. A multiple linear regression model showed that a disulphide/native thiol ratio above 5 and family history of HT are independent predictors of HT.
Conclusions:
Our study showed that dynamic thiol/disulphide homeostasis shifted towards disulphide formation in adolescent patients with primary HT. Understanding the role of thiol/disulfide homeostasis in primary HT might provide new therapeutic intervention strategies for patients.
Hypertension is a major risk factor for coronary heart disease, stroke, and premature death and a leading risk factor for global disease burden. Prevalence for those 18 years and older in the United States has remained around 29% since 1999 with little improvement. Further, approximately one-third of U.S. adults have prehypertension, which is also associated with a graded, increased risk of cardiovascular disease and progression to hypertension. The overall evidence that diet modification can prevent and treat hypertension is strong. The current national guideline of lifestyle modification for blood pressure control includes the DASH eating pattern, sodium reduction, weight loss, increased physical activity, and moderate consumption of alcohol. Concurrent adherence to several recommendations is likely to hold the greatest promise for preventing and treating hypertension and has been shown to be feasible. In addition to addressing unresolved nutritional hypotheses, future research should focus on strategies to motivate and maintain lifestyle changes long term for blood pressure control. At both the population and individual levels, success in dietary and lifestyle intervention relies on multiple levels of support ranging from clinicians to government agencies to private institutes and industries. In particular, partnering with industry to improve the nutritional quality of the food supply, such as reducing sodium, sugar, and saturated and trans fat content of processed foods, and promoting foods and nutrients consistent with the DASH dietary pattern will play a critical role in implementing dietary and lifestyle modifications. Consistent efforts to educate and promote adherence to dietary and lifestyle guidelines by dietetic and other health care professionals are also instrumental to the prevention and management of hypertension.
Thirty six percent of people in USA and Canada regularly use complementary and alternative medicine (CAM) for the prevention and treatment of different diseases, including hypertension. Generally, majority of the hypertensive patients do not disclose the use of such remedies, and also health care providers do not usually ask their hypertensive patients if they use CAM. The widespread consumption of CAM in hypertension requires clear understanding of their underlying mechanism of action, efficacy and safety. This chapter will provide a comprehensive list of CAM commonly used by Americans for the prevention and treatment of hypertension as well as their postulated mechanism of action. Modulation of drug metabolizing enzymes and their safety will also be covered along with the clinical consequences, i.e. drug-herb or herb-disease interactions. patients and healthcare providers should also be careful with using CAM therapies, because not only is there minimal evidence that several CAM products work to treat hypertension, but their safety hasn't been well-established.
Experimental evidence supports a pathogenic role of free radicals or reactive oxygen species (ROS) in the mechanism of hypertension. Indeed, vascular ROS produced in a controlled manner are considered important physiological mediators, functioning as signaling molecules to maintain vascular integrity by regulating endothelial function and vascular contraction‐relaxation. However, oxidative stress can be involved in the occurrence of endothelial dysfunction and related vascular injury. Thus, ROS activity could trigger pathophysiological cascades leading to inflammation, monocyte migration, lipid peroxidation, and increased deposition of extracellular matrix in the vascular wall, among other events. In addition, impairment of the antioxidant capacity associates with blood pressure elevation, indicating potential role of antioxidants as therapeutic antihypertensive agents. Nevertheless, although increased ROS biomarkers have been reported in patients with essential hypertension, the involvement of oxidative stress as a causative factor of human essential hypertension remains to be established. The aim of this chapter is to provide a novel insight into the mechanism of essential hypertension, including a paradigm based on the role played by oxidative stress.
Hypertension is a major public health problem and is one of the most important risk factors for the development of atherosclerosis and vascular events. Although it is a multifactorial condition, hypertension is associated with oxidative stress and endothelial dysfunction leading to increased vascular resistance. These perturbations likely represent both a cause and a consequence of elevated levels of reactive oxygen (ROS) and nitrogen (RNS) species. Mitochondria are important sites of ROS production, and mitochondrial dysfunction, preceding endothelial dysfunction, might favor the development of hypertension. ROS production may also be induced by RNS, which inhibit the respiratory chain, and may be generated through the action of a mitochondrial NO synthase. Mitochondrial uncoupling proteins are involved in both experimental and human hypertension. Finally, an excessive production of ROS may damage mitochondrial DNA, with resultant impairment in the synthesis of some components of the respiratory chain and further ROS production, a vicious cycle that may be implicated in hypertension.
This study was conducted in order to investigate the association between hypertension and oxidative stress-related parameters and to evaluate these parameters in subclinical hypertensive patients and normotensive subjects living in Korea. We attempted to determine whether oxidative stress-related parameters would differ between two groups of 227 newly-diagnosed, untreated (systolic blood pressure (BP) ≥ 130 mmHg and diastolic BP ≥ 85 mmHg) and 130 normotensive subjects (systolic BP < 120 mmHg and diastolic BP < 80 mmHg). General characteristics of the subjects were collected using a simple questionnaire. From subjects' blood, degree of DNA damage in lymphocytes, the activities of erythrocyte superoxide dismutase, catalase, and glutathione peroxidase, level of plasma total radical-trapping antioxidant potential (TRAP), glutathione, and anti-oxidative vitamins, as well as plasma lipid profiles and conjugated diene (CD) were analyzed. Evaluation of the associations of oxidative stress-related parameters with blood pressure of the subjects was performed using Pearson partial correlation and multivariate logistic regression analysis after adjusting for confounding factors. Several oxidative stress-related parameters were higher in subclinical hypertensive patients than in normotensive subjects. Plasma levels of α-tocopherol, β-carotene, TRAP, and activity of GSH-px were significantly lower in subclinical hypertensive patients than in normotensive subjects. Increased levels of DNA damage, lipid peroxidation, triglyceride, total cholesterol, and LDL-cholesterol were observed in subclinical hypertensive patients. These results confirm an association between blood pressure and oxidative stress-related parameters and suggest that the pathogenic role of oxidative stress in hypertension might be significant.
Background The associations between supplement use and certain demographics, lifestyles, health characteristics, and dietary intakes have not been studied in a large population in non-Western societies. The objective of our study was to investigate the association between supplement use and demographics, lifestyles, health characteristics, and dietary intake in a population-based cohort study in Japan. Methods Subjects were the 78 531 participants (45-74 years) who completed a self-administered questionnaire in 1995 or 1998 in a 5-year follow-up survey by the Japan Public Health Center-based prospective Study on cancer and cardiovascular disease. The questionnaire included enquiries about supplement use, occupation, height, weight, smoking, alcohol, physical activity, dietary behaviours, working hours, subjective stress, as well as intakes for 138 foods. Results The supplement users were likely to have formerly smoked or never smoked. Female supplement users were likely to consume alcohol moderately. The prevalence of users was higher in the elderly, the self-employed, those with lower body mass index, greater physical activity, lower frequency of eating prepared food, higher frequency of eating out, and higher stress level in both sexes after mutual adjustment. Mean intakes of energy and nutrients were lower for users than for non-users. Conclusion The demographics, lifestyles, health characteristics, and dietary intakes may need to be adjusted when evaluating the effect of dietary supplements on disease because they can become potential confounding factors.
Despite recent developments in diagnosis and treatment of diseases, individuals with chronic disease use herbal products much more than others. Our study aims to examine the rates of herbal product use, the kinds of used products, source of information, whether the doctors are being informed and cost of the products used in patients with hypertension in our region. The study has been performed with 100 hypertension patients referred to our outpatient clinic. A questionnaire consisted of 9 questions has been used to gather the data about the patients. In our study, the herbal product use in hypertension patients was 53% . The most frequently used herbal products were lemon and garlic. Majority of the patients (83%) reported the source of information about the product as neighbours, relatives, friends or television and radio. While 28% of the patients were using the herbal product regularly everyday, 34% of them were only using these products if their blood pressure increased. Fourty six (87%) patients used these products did not give information to the clinician about the product. Eighty seven per cent of the patients told that the monthly cost of the product they used was less than 50 TL. A significant proportion of the patients with hypertension uses herbal product and they do not give information to the clinicians about the subject. The use of these kind of products without knowing the effects and side-effects may cause undesirable results.
Hypertension is considered the most important risk factor in the development ofcardiovascular disease. An increasing body of evidence suggests that oxidative stress,which results in an excessive generation of reactive oxygen species (ROS), plays a keyrole in the pathogenesis of hypertension. The modulation of the vasomotor systeminvolves ROS as mediators of vasoconstriction induced by angiotensin II, endothelin-1and urotensin-II, among other factors. The bioavailability of nitric oxide (NO), a majorvasodilator, is modulated by the cellular redox status. Under physiological conditions,low concentrations of intracellular ROS are important in normal redox signaling tomaintain vascular function and integrity. However, under pathological conditions, ROScontribute to vascular dysfunction and remodeling through oxidative injury. Increasedproduction of superoxide anion and hydrogen peroxide, decreased NO synthesis anddiminished antioxidant capacity have been found in patients with essential hypertension.Antioxidants are reducing agents that can neutralize these oxidative compounds, whichotherwise damage biomolecules and thereby cause functional and even structuralimpairment of the end-organs. The use of antioxidant vitamins such as vitamins C and Efor protection against vascular endothelial injury has gained considerable interest.Available data support the role of these vitamins as effective antioxidants to counteractthe effects of ROS. In this chapter, the following core hypothesis is evaluated: essentialhypertension is a manifestation of subtle vascular inflammation brought about byheightened oxidative stress. For this purpose, the mechanisms involved in the generation of vascular ROS are discussed, as well as the role of oxidative stress in the pathogenesisof hypertension. Possible therapeutic strategies to overcome the heightened oxidativestress in essential hypertension are suggested.
Essential hypertension is a highly prevalent pathological condition that is considered as one of the most relevant cardiovascular risk factors and is an important cause of morbidity and mortality around the world. Despite the fact that mechanisms underlying hypertension are not yet fully elucidated, a large amount of evidence shows that oxidative stress plays a central role in its pathophysiology. Oxidative stress can be defined as an imbalance between oxidant agents, such as superoxide anion, and antioxidant molecules, and leads to a decrease in nitric oxide bioavailability, which is the main factor responsible for maintaining the vascular tone. Several vasoconstrictor peptides, such as angiotensin II, endothelin-1 and urotensin II, act through their receptors to stimulate the production of reactive oxygen species, by activating enzymes like NADPH oxidase and xanthine oxidase. The knowledge of the mechanism described above has allowed generating new therapeutic strategies against hypertension based on the use of antioxidants agents, including vitamin C and E, N-Acetylcysteine, polyphenols and selenium, among others. These substances have different therapeutic targets, but all represent antioxidant reinforcement. Several clinical trials using antioxidants have been made. The aim of the present review is to provide new insights about the key role of oxidative stress in the pathophysiology of essential hypertension and new clinical attempts to demonstrate the usefulness of antioxidant therapy in the treatment of hypertension.
Cette étude sur les croyances alimentaires a été faite dans le but de déterminer les perceptions des Mauriciens sur l’effet de dix aliments sur la tension artérielle et de les analyser. Les données ont été obtenues à partir d’un échantillon représentatif de la population de Maurice et de Rodrigues. La taille de l’échantillon était de 800 personnes tirées au hasard. Cette étude qui a obtenu l’accord du Comité d’Ethique du Ministère de la Santé et de la Qualité de la Vie de Maurice a demandé un consentement éclairé et écrit de la part de chaque participant. Ce travail a mis en évidence un certain nombre de perceptions présentes parmi les Mauriciens et a démontré leur degré de mise en pratique. Les résultats de cette étude ont fait ressortir le besoin de faire une éducation de la population sur les valeurs nutritives des aliments associés à des croyances culturelles.
We investigated the association of dietary fatty acids and antioxidants with blood pressure in 722 eastern Finnish men aged 54 y, examined in the Kuopio Ischaemic Heart Disease Risk Factor Study in 1984-86. Men with self-reported hypertension or cerebrovascular disease or under antihypertensive medication were excluded. Allowing for the major anthropometric, dietary, medical, and psychological determinants of blood pressure in multivariate regression analyses, both plasma ascorbic acid (p = 0.0008) and serum selenium (p = 0.0017) concentrations had a moderate, independent inverse association, estimated dietary intake of saturated fatty acids had a positive association (p = 0.013), and estimated dietary intake of linolenic acid had an inverse (p = 0.048) association with the mean resting blood pressure. The marked elevation of blood pressure at the lowest levels of plasma ascorbic acid and serum Se concentrations supports the hypothesis that antioxidants play a role in the etiology of hypertension.
Epidemiological evidence suggests that high dietary ascorbic acid reduces gastric cancer risk. It may do this by either reducing N-nitroso compound formation in gastric juice, or by scavenging reactive oxygen species in gastric mucosa. The aim of this study was to discover if potential ascorbic acid protection might be increased by supplementation. Thirty two patients were supplemented with ascorbic acid, 500 mg twice daily for two weeks. Gastric juice, plasma, and upper gastrointestinal biopsy ascorbate concentrations were measured and compared with values in 48 unsupplemented patients. It was found that ascorbic acid and total vitamin C concentrations were considerably higher in biopsy specimens from oesophagus, body, antrum, duodenum, and rectum, compared with values in plasma or gastric juice. Plasma and mucosal concentrations were unaffected by the presence of chronic gastritis but gastric juice concentrations were substantially lower in patients with chronic gastritis than in patients with normal histological assessment (p < 0.01). Patients receiving ascorbic acid supplements had higher ascorbic acid concentrations in plasma (p < 0.001), gastric juice (p < 0.001), and at all biopsy sites in the upper gastrointestinal tract (p < 0.05). Gastric juice ascorbic acid and total vitamin C concentrations in gastritic patients, however, were still less after supplementation than in normal subjects (p < 0.01). These data suggest that high ascorbic acid intake could reduce gastric cancer risk, but its protective effect might be greater if gastritis is treated (for example, by Helicobacter pylori eradication).
Relatively high intakes of vegetables and fruit and relatively low intakes of fat are associated with lower rates of heart disease and many types of cancer. Biomarkers for vegetable and fruit consumption are most useful when applicable across different ages, body weights, diets, and varying patterns of fat intake. This study examined two biomarkers, serum concentrations of beta-carotene and vitamin C, as a function of anthropometric, dietary, and lifestyle factors in a community-based sample of French adults. The interview-based dietary-history method was used to assess dietary intakes of 361 males and 476 females aged 18-94 y resident in the Val-de-Marne district southeast of Paris. Serum beta-carotene was quantified by HPLC and vitamin C was measured by using an automated method. Serum beta-carotene and vitamin C concentrations were positively associated with vegetable and fruit intakes and were negatively linked to the consumption of energy, alcohol, and fat. Multiple-regression analyses showed that serum beta-carotene concentration was predicted by fruit and vegetable intakes but was inversely associated with body mass, energy and alcohol intakes, and tobacco use. Serum vitamin C concentration was positively associated with fruit consumption but was negatively associated with age, body mass, and tobacco use. Serum beta-carotene and vitamin C concentrations are useful biomarkers of vegetable and fruit consumption in the French diet. However, other dietary and lifestyle factors also have a significant effect on circulating concentrations of these antioxidant micronutrients.
Sacks. F. M., B. Rosner and E. H. Kass (Harvard Medical School. Boston. Mass. 02118). Blood pressure in vegetarians. Am J Epidemiol 100:390–398, 1974.—In studies of the etiology of elevated blood pressure (BP) in man, little attention has been accorded to dietary factors other than salt. The BP and individual dietary habits were studied of 210 men and women living in communal households in greater Boston, eating food mainly from vegetable sources. Mean BP for age group 16–29 was 106/60 mm Hg, and the regression coefficient of BP on age was about 0.2; both values are less than those usually found in Western populations. The declared consumption of food of animal origin was highly significantly associated with systolic and diastolic BP after the age and weight effects were removed. Significant aggregation of systolic BP levels occurred among unrelated members of communes, before and after removing the effect of age and weight. These data suggest a relation between BP levels and consumption of food from animal sources.
A cross-sectional study on associations between lifestyle factors and cancer risks was conducted in five areas of Japan. The study design and participation rate were described in the part I. In this paper, we showed the baseline data of lifestyle and health-related items with special reference to geographic difference. Medical history of peptic ulcer, family history of stomach cancer and any cancer, smoking and drinking habits, anthropometric features such as height, weight and body mass index, and biochemical parameters such as HDL cholesterol, uric acid, and abnormal GOT were significantly different among men by study areas. Urinary excretion level of sodium, potassium, calcium and magnesium, and nutritional intake level of energy, fat and carbohydrate also revealed the significant differences. The wives of male participants also showed the similar geographical difference. Correlation analysis was conducted between age-adjusted mortality rates of selected cancer sites and prevalence or average values of lifestyle and health-related factors. Significant associations were found between esophageal cancer and consumption of alcohol and cigarette, and stomach cancer and both medical histories of peptic ulcer and salt excretion in 24-h urine. J Epidemiol, 1992; 2 : 83-89.
The suggested association between atrophic gastritis as a precursor lesion and subsequent high risk of gastric cancer was examined at the population level in a cross-sectional study of men 40 to 49 years of age in 5 populations with different gastric cancer mortalities. Subjects totalled 634 men, randomly selected from each population of about 100,000, whose atrophic gastritis was diagnosed serologically based on a combination of the serum pepsinogen I (PG I) level<70 ng/ml and pepsinogen l/pepsinogen II (PG l/PG II) ratio<3.0. The number of atrophic gastritis cases discriminated was 121 among 624 evaluated men (19.4% overall) and its prevalence rates in 5 areas (range : 9.4-26.8%) correlated almost perfectly (r=0.999, p<0.0001) with age-adjusted mortality rates averaged for 1985-89 for gastric cancer (range : 17.3-49.1 per 100,000). Although some misclassifications could not be denied, especially in discriminating mild/moderate cases, which were separated from severe ones diagnosed more definitively under stricter criteria of PG 1<30 ng/ml and PG l/PG II ratio<2.0, it was unlikely that they affected the above correlation significantly, since a similar good correlation was observed even when a criterion of PG l/PG II ratio<2.5 alone, for which high specificity and sensitivity are known, was applied. Thus, the strong correlation found in the present study not only suggests that the number of middle-aged men with atrophic gastritis may be a basis on which gastric cancer mortality in an area can be determined almost exclusively but also that the serologiccal diagnosis is useful in screening of a group of high risk for gastric cancer. Therefore, this diagnostic method provides a practical method of gastric cancer prevention, although a combination with other methods to diagnose particularly mild/moderate atrophic gastritis is recommended for following-up the high-risk group on an individual basis. © 1993, Japan Epidemiological Association. All rights reserved.
Smoking and drinking habits at baseline survey among 110,896 male and female residents aged 40-69 are reported as part of an ongoing prospective population-based cohort in 11 geographically diverse health centers in Japan. The age-adjusted proportion of current and former smokers was 54.8% and 21.8% in males and 8.3% and 2.1% in females, respectively. Mean age at initiation of smoking in males and females was 20.6 and 27.8 years of age, respectively. In males, the age-adjusted proportion of those who drink almost daily was 49.1 % and that of those who drink almost never was 19.7%, while in females, it was 5.9% and 71.6%, respectively. When compared by health center, the proportion of male current smokers was lower in Miyako and Ishikawa, both located in Okinawa Prefecture, while in females the proportion was higher in urban areas, such as Katsushika and Suita. The proportion of those who drink almost daily in males was higher in Yokote, Kashiwazaki, Katsushika and Suita, and lower in Ishikawa and Miyako, but in Ishikawa and Miyako, the proportion of those who drink at social events was higher. In females, the proportion of those who drink almost daily was higher in urban areas. There was substantial variation in the types of alcohol beverages consumed by males. In contrast, alcohol consumption in females comprised mainly beer.
Background
In addition to the treatment of specific cardiovascular risk factors, intervention which interferes with the general mechanisms of atherosclerosis could further reduce the incidence of cardiovascular events. We aimed to investigate in general practice the efficacy of antiplatelets and antioxidants in primary prevention of cardiovascular events in people with one or more major cardiovascular risk factors.
Methods
We did a randomised controlled open 2·2 factorial trial to investigate low-dose aspirin (100 mg/day) and vitamin E (300 mg/day) in the prevention of cardiovascular events, in people with one or more of the following: hypertension, hypercholesterolaemia, diabetes, obesity, family history of premature myocardial infarction, or individuals who were elderly.
Findings
4495 people (2583 female, mean age 64·4 years) were included in the trial. After a mean follow-up of 3·6 years the trial was prematurely stopped on ethical grounds when newly available evidence from other trials on the benefit of aspirin in primary prevention was strictly consistent with the results of the second planned interim analysis. Aspirin lowered the frequency of all the endpoints, being significant for cardiovascular death (from 1·4 to 0·8%; relative risk 0·56 [95% CI 0·31–0·99]) and total cardiovascular events (from 8·2 to 6·3%; 0·77 [0·62–0·95]). Severe bleedings were more frequent in the aspirin group than the no-aspirin group (1·1% vs 0·3%; p<0·0008). Vitamin E showed no effect on any prespecified endpoint. Analyses were by intention-to-treat.
Interpretation
In women and men at risk of having a cardiovascular event because of the presence of at least one major risk factor, low-dose aspirin given in addition to treatment of specific risk factors contributes an additional preventive effect, with an acceptable safety profile. The results on vitamin E's cardiovascular primary preventive efficacy are not conclusive per se, although our results are consistent with the negative results of other large published trials on secondary prevention.
OBJECTIVES: To assess whether systemic oxidative stress can predict the risk of first myocardial infarction, ischemic stroke, and congestive heart failure.
DESIGN: A longitudinal study started in 1992 and completed in 1997.
SETTING: Community-based, outpatient.
PARTICIPANTS: 102 apparently healthy, community-dwelling subjects age 80 and older from the Vibrata valley, Teramo, Italy.
MEASUREMENTS: Plasma vitamin E, β-carotene, vitamin C, fluorescent products of lipid peroxidation (FPLPs), and serum lipids were determined at enrollment.
RESULTS: Thirty-two cardiovascular events were recorded in 47.4 months of follow-up. The subjects with vitamin E levels in the highest quartile had a risk of cardiovascular events one-sixth those with vitamin E levels in the lowest quartile (relative risk (RR) = 0.16; 95% confidence interval (CI) = 0.04–0.55). The subjects with FPLPs in the highest quartile had a risk seven times greater than those with FPLPs in the lowest quartile (RR = 7.61; 95% CI = 2.23–25.96). No association was observed for vitamin C, β-carotene, or total cholesterol. Multivariate adjustment for known risk factors did not significantly change the results.
CONCLUSIONS: Our results suggest that in apparently healthy, community-dwelling very old subjects, base-line plasma concentration of vitamin E and FPLPs predicts the risk of future cardiovascular events. We confirm previous data showing that total cholesterol is not a predictor of cardiovascular disease in people age 80 and older.
In order to clarify the relationship of vitamin C to hypertension, a tablet of 1000 mg ascorbic acid (AA) or a placebo was supplied daily to 20 adult subjects for two 6-week periods in a randomized, crossover design. The subjects consumed self-selected diets and were in good vitamin C status; and 12 were classified as borderline hypertensive. AA supplementation reduced systolic blood pressure and pulse pressure but did not affect diastolic blood pressure. Total plasma cholesterol, high density lipoprotein cholesterol and total triglyceride were not affected. It appears that vitamin C supplementation may have therapeutic value in human hypertensive disease.
Serum pepsinogen I and II levels have recently become popular as indicators of atrophic gastritis in epidemiological studies. Previous studies show a significant association between serum pepsinogen levels and endoscopically diagnosed atrophic gastritis. This study assesses the level of agreement between the degree of atrophic gastritis as assessed by endoscopic examination and by serum pepsinogen assays. Study subjects were 200 outpatients at Aichi Cancer Center Hospital, Nagoya, Japan, who were endoscoped between February and August 1995. Agreement of the degree of atrophic gastritis was assessed by endoscopic examination and by serum pepsinogen levels. Agreement in assessing the extent of atrophic gastritis between the two methods was 57%, and the presence of atrophic gastritis was 79%. Serum pepsinogen assays identify the majority of patients with atrophic gastritis, although they are less useful in assessing the degree of atrophy in detail.
A rapid simple micromethod for the determination of l-ascorbic acid in plasma and other biological tissues using orthophosphoric acid and ferric iron is presented. The ferric iron is reduced by ascorbic acid producing ferrous iron which is coupled with α,α′-dipyridyl. The method is highly sensitive and can be used to accurately determine 0.1 μg of the vitamin in samples of plasma and other biological tissues. Plasma levels of ascorbic acid from adult humans, infants and cord blood are given. Tissue distribution studies of the vitamin in mice and guinea pigs are presented. The specificity of the method is discussed.
In studies of the etiology of elevated blood pressure (BP) in man, little attention has been accorded to dietary factors other than salt. The BP and individual dietary habits were studied of 210 men and women living in communal households in greater Boston, eating food mainly from vegetable sources. Mean BP for age group 16 to 29 was 106/60 mm Hg, and the regression coefficient of BP on age was about 0.2; both values are less than those usually found in Western populations. The declared consumption of food of animal origin was highly significantly associated with systolic and diastolic BP after the age and weight effects were removed. Significant aggregation of systolic BP levels occurred among unrelated members of communes, before and after removing the effect of age and weight. These data suggest a relation between BP levels and consumption of food from animal sources.
Correlation analyses between serum ascorbic acid and several risk factors of cerebro- and cardio-vascular diseases were performed on apparently healthy adults (194 persons) aged 30-39 in order to estimate possible functions of ascorbic acid in the prevention of the disease. Serum ascorbic acid had an inverse and the strongest association with systolic blood pressure among the risk factors including blood pressure, total cholesterol, triglyceride, gamma-GTP and obesity. The association was independent of the other variables tested. When the subjects were divided into three different serum ascorbic acid level groups, the prevalence of hypertension (140/90 mmHg and above) was decreased with an increase in the ascorbic acid level. The close relationship of serum ascorbic acid and blood pressure observed in the study suggests that ascorbic acid may have a preventive function against hypertension, or a low ascorbic acid status in hypertensives may promote the further development of arteriosclerosis by the lack of favorable effect of ascorbic acid on lipid metabolism and others.
To examine the possible effect of gastritis on the endocrine component of pepsinogen secretion, we determined relationships among gastric mucosal histologic characteristics and serum levels of pepsinogen I and pepsinogen II in 170 first-degree relatives of patients with pernicious anemia. Sixtyfour had normal fundic gland mucosa, 66 had superficial gastritis, 17 had mild or moderate atrophic gastritis, and 23 had severe atrophic gastritis. In superficial gastritis, serum pepsinogen I and pepsinogen II were both significantly higher than normal, but the percentage rise in pepsinogen II was significantly greater than the rise in pepsinogen I. In mild/ moderate atrophic gastritis, pepsinogen I did not differ from normal, but pepsinogen II was significantly elevated, while in severe atrophic gastritis, pepsinogen II did not differ from normal, but pepsinogen I was significantly decreased. The nonparallel changes in serum pepsinogen I and pepsinogen II levels resulted in a decrease in the pepsinogen I to pepsinogen II ratio from 6.2 ± 0.2 in subjects with normal fundic gland mucosa to 4.3 ± 0.2, 2.9 ± 0.4, and 0.7 ± 0.2, respectively, in those with superficial gastritis, mild to moderate atrophic gastritis, and severe atrophic gastritis. The pepsinogen I to pepsinogen II ratio in combination with the absolute level of serum pepsinogen I correctly predicted the histologic status of the gastric mucosa in 119 of the 170 subjects, 70.0%. The results indicate that (a) increasing severity of gastritis is associated with nonparallel alterations in serum levels of pepsinogen I and pepsinogen II, (b) that these changes lead to a progressive decrease in the pepsinogen I to pepsinogen II ratio, and (c) that the pepsinogen I to pepsinogen II ratio, in combination with pepsinogen I, is predictive of the histologic status of the gastric mucosa.
To determine whether vitamin C status, as measured by dietary intake and plasma ascorbic acid concentration, is related to mortality from stroke and coronary heart disease in people aged 65 and over.
A 20 year follow up study of a cohort of randomly selected elderly people living in the community who had taken part in the 1973-4 Department of Health and Social Security nutritional survey and for whom dietary and other data had been recorded.
Eight areas in Britain (five in England, two in Scotland, and one in Wales).
730 men and women who had completed a seven day dietary record and who had no history or symptoms of stroke, cerebral arteriosclerosis, or coronary heart disease when examined by a geriatrician in 1973-4.
Mortality from stroke was highest in those with the lowest vitamin C status. Those in the highest third of the distribution of vitamin C intake had a relative risk of 0.5 (95% confidence interval 0.3 to 0.8) compared with those in the lowest third, after adjustment for age, sex, and established cardiovascular risk factors. The relation between vitamin C intake and stroke was independent of social class and other dietary variables. A similar gradient in risk was present for plasma ascorbic acid concentrations. No association was found between vitamin C status and risk of death from coronary heart disease.
In elderly people vitamin C concentration, whether measured by dietary intake or plasma concentration of ascorbic acid, is strongly related to subsequent risk of death from stroke but not from coronary heart disease.
This study relates antioxidant status and blood pressure (BP) in 168 healthy residents of Augusta, GA, following usual diets. BP ranges were systolic (S) 84-152, mean 112 +/- 1 mm Hg, and diastolic (D) 52-96, mean 72 +/- 1 mm Hg. Plasma concentrations of ascorbic acid (AA) were significantly inversely related to SBP (r = -0.18, P < 0.05) and DBP (r = -0.20, P < 0.01); with regression equations SBP vs AA = -0.083C + 116 and DBP = -0.077C + 76. Highest and lowest quintiles of AA differed significantly in mean SBP (108 +/- 2, 113 +/- 2 mm Hg) and DBP (69 +/- 1, 74 +/- 2), P < 0.05. Plasma AA concentrations were significantly lower in the smokers. By deleting smokers, the inverse relations of SBP and DBP with plasma AA and the slopes of the equation were enhanced. Plasma selenium, alpha-tocopherol, alpha-tocopherol:cholesterol ratio, retinol and taurine were not related to BP; whereas male gender, body mass index, body fat distribution, plasma cholesterol, low density lipoprotein cholesterol, and triglycerides correlated.
To examine the cross-sectional relationship between blood pressure and plasma vitamin C.
A cross-sectional analysis.
A population-based study.
The subjects were 835 men and 1025 women aged 45-75 years registered with general practices in Norfolk.
Completion of health and lifestyle questionnaire and attendance for a health check.
Diastolic blood pressure (DBP), systolic blood pressure (SBP) and plasma vitamin C level.
The mean SBP was 135.8 +/- 18.5 mmHg (mean +/- SD) and the mean DBP was 82.5 +/- 11.3 mmHg. The mean plasma vitamin C level was 52.6 +/- 19.7 mumol/l. The plasma vitamin C level was negatively correlated both with SBP and with DBP. These correlations persisted after adjustment for age, sex and body mass index. Adjusting for other confounders including cigarette smoking, physical activity and alcohol intake did not alter the observed association. Exclusion of subjects taking vitamin supplements and those with known hypertension did not affect the results. The differences in SBP and in DBP for a 50 mumol/l difference in vitamin C, estimated using linear regression, were -3.6 and -2.6 mmHg, respectively.
The plasma vitamin C level may be a marker of other factors; nevertheless, these results are consistent with other published work indicating that a high intake of vitamin C from food confers protection against raised blood pressure and strokes.
A self-administered food frequency questionnaire (FFQ) has been used commonly in epidemiologic studies of diet and chronic diseases. The analysis of dietary data in the target population is useful for designing a new questionnaire. The authors studied the major food sources of nutrient intakes in the Japanese population in order to develop a FFQ for a population-based prospective study. Subjects were 180 men aged 40-49 years and their 155 spouses who were sampled from four Public Health Center districts. Weighed food records over three consecutive weekdays were collected during the winters of 1989-1991. All foods reported were grouped into 154 items, and the percent contribution of each food to the total population intake of 15 nutrients was computed. Based on these data, a FFQ with 138 items was developed. The food list covered well the population intake of most nutrients (median = 83%, range = 55-91%), except for lipid (70%) and sodium (55%). The questionnaire was applied to the prospective study conducted in the same areas where the dietary data were collected, and an investigation to assess its reproducibility and validity is currently underway.
This chapter presents analyses of relations of dietary variables to blood pressure, systolic (SBP) and diastolic (DBP), for men in the special intervention (SI) and usual care (UC) groups in the Multiple Risk Factor Intervention Trial. For each dietary factor, analyses were done at baseline, for trial years 1-6, and for change from baseline to years 1-6. Analyses were done for all participants and for men receiving or not receiving antihypertensive drug treatment and were controlled for age, race, education, serum cholesterol, smoking, special diet status, and (for specific nutrients) body mass index and alcohol intake. Nutrient data for trial years 1-6, which are based on four or five dietary recalls per man, are more reliable than the baseline or change data, which are based on only one recall. Therefore, this summary focuses on data for trial years 1-6, for SI and UC men pooled. Regression analyses confirmed direct independent relations of body mass index, alcohol intake, sodium, and ratio of sodium to potassium to SBP and DBP, and an inverse relation of potassium to SBP and DBP. Dietary starch was directly related to SBP and DBP; dietary saturated fatty acid and cholesterol and Keys score were directly related to DBP; dietary magnesium, fiber, and caffeine were inversely related to SBP and DBP; and dietary protein, polyunsaturated fatty acids, the ratio of polyunsaturated to saturated fatty acid, and other simple carbohydrates were inversely related to DBP. Method problems, all tending to produce underestimations, are also reviewed.
To examine the association between plasma vitamin C concentrations and the risk of acute myocardial infarction.
Prospective population study.
Eastern Finland.
1605 randomly selected men aged 42, 48, 54, or 60 who did not have either symptomatic coronary heart disease or ischaemia on exercise testing at entry to the Kuopio ischaemic heart disease risk factor study in between 1984 and 1989.
Number of acute myocardial infarctions; fasting plasma vitamin C concentrations at baseline.
70 of the men had a fatal or non-fatal myocardial infarction between March 1984 and December 1992.91 men had vitamin C deficiency (plasma ascorbate < 11.4 mumol/l, or 2.0 mg/l), of whom 12 (13.2%) had a myocardial infarction; 1514 men were not deficient in vitamin C, of whom 58 (3.8%) had a myocardial infarction. In a Cox proportional hazards model adjusted for age, year of examination, and season of the year examined (August to October v rest of the year) men who had vitamin C deficiency had a relative risk of acute myocardial infarction of 3.5 (95% confidence interval 1.8 to 6.7, P = 0.0002) compared with those who were not deficient. In another model adjusted additionally for the strongest risk factors for myocardial infarction and for dietary intakes of tea fibre, carotene, and saturated fats men with a plasma ascorbate concentration < 11.4 mumol/l had a relative risk of 2.5 (1.3 to 5.2, P = 0.0095) compared with men with higher plasma vitamin C concentrations.
Vitamin C deficiency, as assessed by low plasma ascorbate concentration, is a risk factor for coronary heart disease.
It is known that obesity, sodium intake, and alcohol consumption factors influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure.
We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a "combination" diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels.
At base line, the mean (+/-SD) systolic and diastolic blood pressures were 131.3+/-10.8 mm Hg and 84.7+/-4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P<0.001 for each); the fruits-and-vegetables diet reduced systolic blood pressure by 2.8 mm Hg more (P<0.001) and diastolic blood pressure by 1.1 mm Hg more than the control diet (P=0.07). Among the 133 subjects with hypertension (systolic pressure, > or =140 mm Hg; diastolic pressure, > or =90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003).
A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension.
We have initiated a population-based, double-blind, randomized controlled trial to examine the effects of supplementation of beta-carotene and vitamin C on the incidence of gastric cancer. The subjects were participants in an annual health screening program conducted by four municipalities in Akita prefecture, one of the regions with the highest mortality from gastric cancer in Japan. We measured their serum levels of pepsinogens (PGs) I and II, and asked persons diagnosed with chronic atrophic gastritis (defined as PG I < 70 ng/ml and PG I/PG II ratio < 3.0) to take diet supplements containing 0 or 15 mg/day beta-carotene and 50 or 500 mg/day vitamin C for 5 years. During the first year of recruitment conducted in one village from June through September, 1995, 52% (635/1214) of screening participants had chronic atrophic gastritis and 73% (439/602) of eligible persons responded. However, in response to a National Cancer Institute press report released on January 18, 1996, indicating that two beta-carotene trials had shown no benefit and potential harm from the supplement, we discontinued the beta-carotene and continued with the trial using only vitamin C. Of 397 participants remaining at this point, 77% (305) consented to stay in the study. The results indicate that a randomized controlled trial for cancer prevention is feasible in the Japanese asymptomatic population.
Evidence from observational epidemiologic studies has indicated that antioxidants consumed through the diet or as dietary supplements lower the risk of developing atherosclerotic cardiovascular disease. Evidence suggesting that the major mechanism for the protective effect of antioxidants is mediated through decreased oxidation of lipids, particularly low-density lipoprotein (LDL) cholesterol is accumulating. Other evidence, however, suggests that antioxidants may influence traditional modifiable cardiovascular risk factors such as the blood pressure and serum lipids favorably. The purpose of this study was to determine the effect of antioxidant vitamin supplementation on modifiable risk factors for atherosclerotic cardiovascular disease.
A randomized, placebo-controlled, clinical trial of antioxidant vitamin supplementation, conducted at a single community-based clinical research center.
We assigned 297 retired teachers who were members of the Maryland Retired Teachers Association randomly to 2-4 months of dietary supplementation with placebo or combined antioxidant vitamin capsules providing 400 IU/day vitamin E, 500 mg/day vitamin C, and 6 mg/day beta-carotene. The outcome measures were the blood pressure, fasting serum total cholesterol, high-density lipoprotein cholesterol, LDL cholesterol, and fasting glucose.
After 2-4 months of supplementation the combined antioxidant supplement had had no significant effect on the systolic and diastolic blood pressures, fasting serum lipids (total cholesterol, high-density lipoprotein cholesterol, and LDL cholesterol) and fasting glucose, with unadjusted and adjusted analyses.
Data from this trial suggest that the protective effect from antioxidant vitamin supplementation, if there is one, likely results from mechanisms other than modification of traditionally modifiable cardiovascular risk factors.
Plasma levels of ascorbic acid are assumed to be determined not only by dietary amount of ingested vitamin C, but also by other dietary and nondietary factors. To assess the predictability of plasma ascorbic acid level in Japanese men, we examined its association with dietary sources of vitamin C and other lifestyle factors.
In a cross-sectional study of 621 healthy men aged 40-49 years who were sampled randomly from five areas in Japan, the weekly intake frequency of foods rich in vitamin C (< 1, 1-2, 3-4, > or = 5 days/week), alcohol consumption per week, use of vitamin C supplements, and smoking were assessed by use of a food-frequency questionnaire (FFQ) (all subjects) and a 3-day weighed dietary record (DR) from 203 volunteers.
In univariate analyses of FFQ data, the intake frequency of fruit (R2 = 0.12), pickled vegetables (R2 = 0.03), potatoes (R2 = 0.01), and alcohol consumption (R2 = 0.02) were significant determinants of plasma ascorbic acid in addition to supplement use and study area. In a multivariate analysis, four FFQ categories of fruit intake accounted for 19% of the variation in plasma ascorbic acid among nonsupplement users after adjustment for study area and alcohol intake. The association between plasma ascorbic acid level and quartile of dietary vitamin C intake (mg/day) measured by DR was weaker (R2 = 0.04) than the association between plasma ascorbic acid level and dietary intake of fresh fruit (g/day) (R2 = 0.09).
The predictability of plasma ascorbic acid by a four-category FFQ assessment of fruit intake was superior to calculated vitamin C or fruit intake assessed by detailed DR.
The hypothesis that antioxidant vitamins might reduce cardiovascular disease risk is based on a large body of both basic and human epidemiological research. One of the most consistent findings in dietary research is that those who consume higher amounts of fruits and vegetables have lower rates of heart disease and stroke as well as cancer. Recent attention has focused on the antioxidant content of fruits and vegetables as a possible explanation for the apparent protective effects. Basic research provides a plausible mechanism by which antioxidants might reduce the risk of atherosclerosis. A large number of descriptive, case-control, and cohort studies provide data suggesting that consumption of antioxidant vitamins is associated with reduced risks of cardiovascular disease. These data raise the question of a possible role of antioxidants, such as vitamins C and E and beta-carotene, in the primary prevention of cardiovascular disease, but they do not provide a definitive answer. Randomized trial data will be essential in fully assessing whether or not there is a causal effect of antioxidants in reducing the risk of cardiovascular disease. Results from several large-scale randomized trials of antioxidant supplements are now available, and additional trial data should be forthcoming in the near future, which will better define the role of antioxidants in the primary and secondary prevention of atherosclerotic disease. At this point, antioxidants represent a possible but as yet unproven means to reduce the risk of cardiovascular disease.
To examine the relationship between serum vitamin C concentration and blood pressure level, a cross-sectional study was conducted. The subjects were 919 men and 1,266 women aged 40 years and over in a Japanese provincial city, Shibata, Niigata Prefecture. The mean and standard deviation of systolic blood pressure (SBP) were 134.0 +/- 20.0 mmHg for men and 128.3 +/- 20.8 mmHg for women, and those of diastolic blood pressure (DBP) were 81.0 +/- 11.7 mmHg and 75.8 +/- 11.4 mmHg, respectively. The mean and standard deviation of serum vitamin C were 42.5 +/- 18.6 mumol/L for men and 56.8 +/- 16.5 mumol/L for women. SBP and DBP were both inversely correlated with serum vitamin C concentration. The means of SBP or DBP were calculated for quartiles of serum vitamin C, and the significant inverse relationship was observed in any sex and age group. The inverse association persisted after adjustment for possible confounders: body mass index, serum total cholesterol, alcohol consumption, smoking, physical activity, antihypertensive medication, and dietary intake of salt, calcium, and potassium. Serum vitamin C appeared to be inversely related with both SBP and DBP in this Japanese population, although further intervention and experimental studies were required to establish the cause-effect relationship.
Low-fat soluble-antioxidant status is associated with an increased risk of heart disease.
The aim of this study was to examine whether low plasma concentrations of vitamin C confer an independent risk of acute myocardial infarction (AMI).
Male patients (n = 180) aged <65 y with a first AMI and without an existing diagnosis of angina (>6 mo) who were admitted within 12 h after onset of symptoms were compared with apparently healthy volunteers (n = 177). Plasma concentrations and dietary intakes of vitamin C were determined during hospitalization and 3 mo later.
Compared with the control subjects, the patients had higher total cholesterol and lower HDL-cholesterol concentrations and more of them smoked. The relative risk of AMI for the lowest compared with the highest quintile of plasma vitamin C during hospitalization (14.5 and >60.5 micromol/L, respectively) was 8.37 (95% CI: 3.28, 21. 4) after adjustment for classic risk factors. At 3 mo, mean (+/-SEM) plasma vitamin C concentrations in patients had increased significantly, from 19.6 +/- 1.2 to 35.1 +/- 1.9 micromol/L (P < 0. 001) and no longer conferred a risk of AMI [relative risk: 1.02 (95% CI: 0.51, 2.03)]. Habitual dietary vitamin C intake of patients (before AMI) did not differ significantly from that of control subjects. The increase in plasma vitamin C after recovery from the infarction could not be explained by a similarly large increase in dietary vitamin C.
A low plasma concentration of vitamin C was not associated with an increased risk of AMI, irrespective of smoking status. The apparent risk of AMI due to a low plasma vitamin C concentration was distorted by the acute phase response.
Epidemiological evidence suggests that vitamin C may decrease the risk of stroke. The purpose of the present study was to examine the association of serum vitamin C concentration with the subsequent incidence of stroke.
In a Japanese rural community, a cohort of 880 men and 1241 women aged 40 years and older who were initially free of stroke was examined in 1977 and followed until 1997. The baseline examination included a measurement of serum vitamin C concentration. The incidence of stroke was determined by annual follow-up examinations and registry.
During the 20-year observation period, 196 incident cases of all stroke, including 109 cerebral infarctions and 54 hemorrhagic strokes, were documented. Strong inverse associations were observed between serum vitamin C concentration and all stroke (sex- and age-adjusted hazard ratios were 0.93, 0.72, and 0.59, respectively, for the second, third, and fourth quartiles compared with the first quartile; P for trend=0.002), cerebral infarction (0.71, 0.59, and 0.51; P for trend=0.015), and hemorrhagic stroke (0.89, 0.75, and 0. 45; P for trend=0.013). Additional adjustments for blood pressure, serum total cholesterol, body mass index, physical activity, smoking, alcohol drinking, antihypertensive medication, atrial fibrillation, and history of ischemic heart disease did not attenuate these associations markedly.
Serum vitamin C concentration was inversely related to the subsequent incidence of stroke. This relationship was significant for both cerebral infarction and hemorrhagic stroke. Additional mechanistic hypotheses may be required to explain our findings.
Free radicals and oxidation are involved in several aspects of blood pressure physiology. We investigated the relationship between blood pressure and antioxidants, including plasma ascorbic acid (AscA), in a 17-week controlled-diet study. Study subjects included 68 men aged 30 to 59 years who had a mean diastolic blood pressure of 73.4 mm Hg and a mean systolic blood pressure of 122.2 mm Hg. One month of vitamin C depletion was followed by 1-month repletion with 117 mg/d, repeated twice. All food and drink were provided in the study. Subjects did not smoke or drink alcohol, all consumed fruits and vegetables, and body weight was maintained. Plasma was assayed periodically for AscA, alpha-tocopherol, carotenoids, and lipids. Plasma AscA was inversely related to diastolic blood pressure 1 month later (correlation -0.48, P:<0.0001). Persons in the bottom fourth of the plasma AscA distribution had >7 mm Hg higher diastolic blood pressure than did those in the top fourth of the plasma AscA distribution. Multivariate analysis with control for age, body mass index, other plasma antioxidants, and dietary energy, calcium, fiber, sodium, and potassium did not reduce the plasma AscA effect. One fourth of the variance in diastolic blood pressure was accounted for by plasma AscA alone. Plasma AscA was also significantly associated with systolic blood pressure in logistic regression. Vitamin C may be an important component of the effectiveness of fruits and vegetables in the reduction in blood pressure, and tissue AscA levels may be important in the maintenance of low blood pressure. Long-term intervention studies are warranted.
To assess whether systemic oxidative stress can predict the risk of first myocardial infarction, ischemic stroke, and congestive heart failure.
A longitudinal study started in 1992 and completed in 1997.
Community-based, outpatient.
102 apparently healthy, community-dwelling subjects age 80 and older from the Vibrata valley, Teramo, Italy.
Plasma vitamin E, beta-carotene, vitamin C, fluorescent products of lipid peroxidation (FPLPs), and serum lipids were determined at enrollment.
Thirty-two cardiovascular events were recorded in 47.4 months of follow-up. The subjects with vitamin E levels in the highest quartile had a risk of cardiovascular events one-sixth those with vitamin E levels in the lowest quartile (relative risk (RR) = 0.16; 95% confidence interval (CI) = 0.04-0.55). The subjects with FPLPs in the highest quartile had a risk seven times greater than those with FPLPs in the lowest quartile (RR = 7.61; 95% CI = 2.23-25.96). No association was observed for vitamin C, beta-carotene, or total cholesterol. Multivariate adjustment for known risk factors did not significantly change the results.
Our results suggest that in apparently healthy, community-dwelling very old subjects, base-line plasma concentration of vitamin E and FPLPs predicts the risk of future cardiovascular events. We confirm previous data showing that total cholesterol is not a predictor of cardiovascular disease in people age 80 and older.
Smoking and drinking habits at baseline survey among 110,896 male and female residents aged 40-69 are reported as part of an ongoing prospective population-based cohort in 11 geographically diverse health centers in Japan. The age-adjusted proportion of current and former smokers was 54.8% and 21.8% in males and 8.3% and 2.1% in females, respectively. Mean age at initiation of smoking in males and females was 20.6 and 27.8 years of age, respectively. In males, the age-adjusted proportion of those who drink almost daily was 49.1% and that of those who drink almost never was 19.7%, while in females, it was 5.9% and 71.6%, respectively. When compared by health center, the proportion of male current smokers was lower in Miyako and Ishikawa, both located in Okinawa Prefecture, while in females the proportion was higher in urban areas, such as Katsushika and Suita. The proportion of those who drink almost daily in males was higher in Yokote, Kashiwazaki, Katsushika and Suita, and lower in Ishikawa and Miyako, but in Ishikawa and Miyako, the proportion of those who drink at social events was higher. In females, the proportion of those who drink almost daily was higher in urban areas. There was substantial variation in the types of alcohol beverages consumed by males. In contrast, alcohol consumption in females comprised mainly beer.
PIP:
This work analyzes two essays by Anibal Quijano and Paul Singer on urbanization, dependency, social change, and marginality in Latin America and suggests some elements for a theoretical interpretation of urbanization in Latin America. The work is divided into three major sections, each of which examines a specific question. The first section explores whether urban phenomena in Latin America are or are not attributable to a situation of dependency or whether they are derived from capitalism. The second section discusses whether changes in urban society and in the urban profile are also derived from dependency or from capitalism. The third section discusses factors leading to urban concentration and suggests some policies that have not yet been developed for urbanization and development, to be analyzed in later articles. Throughout this work, the theoretical approaches of Quijano and Singer are contrasted, and additional commentary on the author's own views is supplied. It is suggested that a policy to add subsidiary or complementary activities to zones that are currently exclusively agricultural would help to retain some part of rural population growth and would have other desirable effects.
Beta-Carotene and Vitamin A Halted in Lung Cancer Prevention Trial. National Cancer Institute Press Release
- K Smigel
Smigel K. Beta-Carotene and Vitamin A Halted in Lung Cancer Prevention Trial. National Cancer Institute Press Release. Bethesda, Md:
National Institutes of Health, US Department of Health and Human
Services; January 18, 1996.
Beta-Carotene and Vitamin A Halted in Lung Cancer Prevention Trial.National Cancer Institute Press Release. Bethesda Md: National Institutes of Health US Department of Health and Human Services
- K Smigel
Cross-sectional epidemiologic study for assessing cancer risks at the population level. I. Study design and participation rate
- S Tsugane
- F Gey
- Y Ichinowatari
- Y Miyajima
- T Ishibashi
- S Matsushita
- Y Hirota
- T Inami
- M Yamaguchi
- K Karita
- M Kabuto
- Y Takashima
- H Todoriki
- M Tsuda
- M Akabane
- Y Furuichi
- G Hamada
- S Watanabe