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ORIGINAL RESEARCH
Effects of Oral Supplementation With Omega-3 Fatty
Acids on Nutritional State and Inflammatory Markers
in Maintenance Hemodialysis Patients
Afshin Gharekhani, PharmD,*Mohammad-Reza Khatami, MD,†Simin Dashti-Khavidaki, PharmD,*
,
†
Effat Razeghi, MD,†Alireza Abdollahi, MD,‡Seyed-Saeed Hashemi-Nazari, MD, MPH, PhD,§
and Mohammad-Ali Mansournia, MD, MPH, PhD{
Objective: The objective was to determine the effects of omega-3 supplementation on nutritional state and inflammatory markers of
hemodialysis patients.
Design and Methods: This was a randomized, placebo-controlled trial. Adult patients undergoing maintenance hemodialysis were
included. Patients with malignancy, pregnancy, concurrent inflammatory or infectious diseases, or concomitant use of any medication
affecting inflammation status were excluded. The omega-3 group received 6 soft-gel capsules of fish oil (180 mg eicosapentaenoic acid
and 120 mg docosahexaenoic acid in each) daily for 4 months, and the placebo group received corresponding paraffin oil capsules.Nu-
trition indices including body mass index; mid-arm muscle circumference; serum concentrations of albumin, prealbumin, and trans-
ferrin; and serum levels of inflammatory/anti-inflammatory markers including interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-a,
C-reactive protein, ferritin, parathyroid hormone, and ratios of IL-10 to TNF-aand IL-10 to IL-6 were measured before and after 4 months
of intervention.
Results: Twenty patients in the placebo and 25 patients in the omega-3 group completed the study. There were no significant
changes in nutritional markers between the omega-3 and placebo groups after 4 months of intervention. Regression analysis adjusting
post-treatment values of nutrition markers for baseline values, omega-3 treatment, and patients’ baseline demographic and clinical data
revealed that omega-3 treatment was a significant independent predictor of increased serum prealbumin level (182.53; 95% confidence
interval 21.14, 511.18; P5.11). Although slight reduction of inflammatory state was observed in the omega-3 group, no significant dif-
ferences were evident in the mean changes of inflammatory and anti-inflammatory markers between the 2 groups with the exception of
serum ferritin level and the IL-10 to IL-6 ratio, which significantly changed in favor of omega-3 supplementation (P,.001 and P5.003,
respectively).
Conclusions: Omega-3 supplementation in hemodialysis patients produced a slight attenuation in systemic inflammation without any
remarkable effects on nutritional markers.
Ó2014 by the National Kidney Foundation, Inc. All rights reserved.
Introduction
PROTEIN-ENERGY WASTING (PEW) or malnutri-
tion exists in approximately 20% to 50% of chronic he-
modialysis (HD) patients and sharply increases the risk of
morbidity and mortality in this population.
1-3
It frequently
coexists with inflammation and atherosclerosis, which
together form a complex syndrome termed malnutrition-
inflammation-atherosclerosis syndrome.
4
Cardiovascular
diseases represent major causes of mortality in HD patients.
5
Malnutrition-inflammation-atherosclerosis syndrome may
play a pivotal role in the etiology of premature cardiovascular
disease in HD patients.
6
One or more defective cycles can
explain concurrent occurrence of malnutrition, inflamma-
tion, and atherosclerosis. Malnutrition induces some degree
of immune paresis, predisposing individuals to infection and
inflammation. In the meantime, inflammatory and infec-
tious processes promote the production of catabolic and
anorectic cytokines, leading to increased risk of malnutrition
and progressive atherosclerosis.
1,4
Despite recent advancements in improving the nutri-
tional and inflammatory state of chronic HD patients, no
single medication has thus far been able to correct
malnutrition-inflammation complex syndrome.
5,7
Several
published studies have recently demonstrated the
*
Department of Clinical Pharmacy, Faculty of Pharmacy, Tehran University of
Medical Sciences, Tehran, Iran.
†
Nephrology Research Center, Tehran University of Medical Sciences, Tehran,
Iran.
‡
Laboratory Department, Vali-e-Asr Hospital, Tehran University of Medical
Sciences, Tehran, Iran.
§
Department of Epidemiology, School of Public Health, Shahid Beheshti Uni-
versity of Medical Sciences, Tehran, Iran.
{
Department of Epidemiology and Biostatistics, School of Public Health, Teh-
ran University of Medical Sciences, Tehran, Iran.
Support: See Acknowledgments on page 184.
Address correspondence to Simin Dashti-Khavidaki, Pharm D, Faculty of
Pharmacy, Tehran University of Medical Sciences, Tehran, Iran, 1417614411,
PO Box 14155/6451. E-mail: dashtis@sina.tums.ac.ir
Ó2014 by the National Kidney Foundation, Inc. All rights reserved.
1051-2276/$36.00
http://dx.doi.org/10.1053/j.jrn.2014.01.014
Journal of Renal Nutrition, Vol 24, No 3 (May), 2014: pp 177-185 177
Author's personal copy
beneficial effects of omega-3 fatty acids in HD patients,
with most focusing on markers of inflammation and nutri-
tion.
8-12
Perunicic-Pekovic and colleagues reported a
significantly less amount of omega-3 fatty acids in the
composition of erythrocyte membrane phospholipids in
HD patients than healthy controls, leading to a worsened
underlying malnutrition-inflammation condition.
9
How-
ever, clinical trials examining the ability of omega-3 fatty
acids to alleviate malnutrition-inflammation in HD patients
have thus far been inconclusive.
Given the controversial reports about the effects of
omega-3 fatty acids on inflammatory and nutritional state,
this trial was intended to test that administration of omega-
3 fatty acids (eicosapentaenoic acid [EPA] and docosahexa-
enoic acid [DHA]) could correct inflammation and
improve the nutritional state of maintenance HD patients.
Methods
Study Population
The study presented here was conducted as a random-
ized, single-blind, placebo-controlled trial. Adult patients
who were undergoing regular HD treatment for at least
3 months at the HD units of 2 teaching hospitals (Imam
Khomeini Hospital Complex and Sina Hospital) affiliated
with the Tehran University of Medical Sciences, Tehran,
Iran, were screened. Patients were not qualified for the
study if they had a malignancy, malabsorption syndrome,
inflammatory or infectious diseases, medical or surgical
illness in the previous 3 months, hypothyroidism, asthma,
chronic obstructive pulmonary disease, hemoglobinopa-
thies, coagulopathies, or known psychiatric disorders; if
they were participants in a concurrent or recent research
study; if they did not comply with HD or medication
regimens; or if they were pregnant. Subjects taking nonste-
roidal anti-inflammatory drugs, corticosteroids, anticoagu-
lants, omega-3 fatty acid supplementation during the
previous 3 months, immunosuppressants or immunomod-
ulators, or those with hypersensitivity to fish or fish-derived
products were also excluded.
The local Ethics Committee of Tehran University of
Medical Sciences approved the study presented here.
Informed written consent was obtained from all partici-
pants. The trial was registered in the Iranian Registry of
Clinical Trials (registry number IRCT201202203043N5).
Study Protocol
Eligible patients were given 2 soft-gel capsules of either
omega-3 or placebo 3 times daily, provided by Zahravi
Pharmaceutical Company, Tabriz, Iran. Each omega-3
capsule contained 180 mg EPA and 120 mg DHA (a total
of 1,800 mg omega-3 fatty acids per day) whereas placebo
capsules were composed of paraffin oil. The study lasted for
4 months. The size, color, shape, and packaging pattern of
placebo and omega-3 capsules were the same. All partici-
pants were asked to maintain their drug regimen, dietary
habits, and level of physical activity unchanged during
the study period. Compliance was ascertained by providing
participants with the weekly dose of capsules and having
them give the unused capsules back from the prior week
as well as by interviewing each participant individually
thrice weekly to encourage adherence. Moreover, a
nephrologist met each patient monthly during a routine
HD session to increase adherence to the recommended
supplement regimens and to monitor the tolerability and
adverse effects of supplementation. Any adverse effects or
medication changes were recorded over the course of the
study. At baseline and month 4, a 10-mL fasting blood
sample was drawn from each patient immediately before
HD commencement. Serum samples were separated
from blood by centrifugation at 3,000 rpm for 10 minutes
and then stored at 270C for later measurement of serum
prealbumin, albumin, transferrin, ferritin, intact parathy-
roid hormone (iPTH), and proinflammatory (interleukin
[IL]-6, tumor necrosis factor [TNF]-a, C-reactive protein
[CRP]) and anti-inflammatory cytokine (IL-10) concen-
trations.
Measurements
Nutritional status of the patients was assessed using mea-
surement of serum albumin by the bromocresol green
colorimetric method (Autoanalyzer BT3000, Biotechnica,
Italy), transferrin by the turbidimetry method (Selectra E,
Elitec, France), and prealbumin by an enzyme-linked
immunosorbent assay kit (Bioassay Technology Laboratory,
Shanghai Crystal Day Biotech Co., Ltd., Shanghai, China).
Mid-arm muscle circumference (MAC), dry body weight
(weight after HD treatment), and body mass index (BMI)
were also measured.
Serum CRP level was measured by a turbidimetric
method (Autoanalyzer BT3000, Biotechnica, Italy). Serum
IL-6, TNF-a, and IL-10 were measured using enzyme-
linked immunosorbent assay kits (Bioassay Technology
Laboratory).
Dialysis dose (termed as single-pool Kt/V urea) was
calculated for each patient at the beginning and after
4 months of intervention using existing software that is
based on pre- and postdialysis serum urea nitrogen concen-
trations, dialysis time, ultrafiltration volume, and postdialy-
sis weight.
Statistical Methods
All statistical tests were performed using Stata software
(StataCorp, 2011, Stata Statistical Software: Release 12.
College Station, TX, StataCorp LP). The normality of
distributions of continuous variables was tested by quantile
normal plot, normal probability plot, and the Kolmogorov-
Smirnov test. Categorical variables were compared be-
tween groups using the c
2
test. Two independent-sample
ttests and the Wilcoxon-Mann-Whitney test were used
for a crude comparison of means for variables with normal
and non-normal distributions, respectively. Furthermore,
GHAREKHANI ET AL178
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we estimated the effect of omega-3 treatment on nutrition
indices using the linear regression model with omega-3
treatment, the baseline value of nutrition marker, the pre-
and postintervention values of cytokines, and patients’ de-
mographic and clinical data as explanatory variables.
Because of the non-normality and heterogeneity of vari-
ances of the residual distributions, we used a nonparametric
bootstrap method with 2,000 replications to obtain empir-
ical standard errors and bias-corrected and accelerated con-
fidence intervals. Categorical data were reported as number
and percentage whereas continuous data were expressed as
mean 6standard deviation (SD). Pvalues less than .05 or a
confidence interval not including a null value were consid-
ered statistically significant.
Results
Figure 1 displays the screening and randomization proce-
dure of the study. Sixty-four of 155 patients that were
screened for eligibility fulfilled the entrance criteria
(41%). Of those, 54 patients consented to consume the
supplements and were included in the trial. There were 9
dropouts (2 in the omega-3 and 7 in the placebo group)
during the study; thus, 45 subjects (20 in the placebo and
25 in the omega-3 group) completed the intervention
period of the study, and their data were included in the final
analysis. A summary of baseline characteristics of patients
who completed the study is presented in Tab l e 1. Both
groups were comparable at baseline with respect to the de-
mographic (gender and age) and clinical (HD duration and
underlying causes of end-stage renal disease) data. Dialysis
dose was significantly lower in the placebo group than
the omega-3 group at baseline, but this difference did not
persist during the study so that 2 groups were comparable
for dialysis dose at the end of the study (data not shown).
In search to clarify the effect of omega-3 fatty acids on
systemic inflammation in HD subjects, we observed that
Figure 1. Study flowchart of patient screening and randomization procedure.
Table 1. Patients’ Demographic and Clinical Data at Baseline in the Placebo and Omega-3 Group
Characteristics Placebo (n520) Omega-3 Fatty Acids (n525) P
Age (y) (6SD) 57.2 (615.19) 56.8 (613.09) .925
Sex, n(%) .592
Females 8 (40) 12 (48)
Males 12 (60) 13 (52)
Hemodialysis duration (mo) (6SD) 72.05 (660.51) 59.88 (645.69) .450
Dialysis adequacy (Kt/V) 1.25 60.17 1.43 60.24*.010*
Cause of end-stage renal disease, n(%) .624
Diabetes 7 (35) 12 (48)
Hypertension 8 (40) 9 (36)
Other causes 5 (25) 4 (16)
Age and hemodialysis duration are expressed as mean 6SD.
*P,.05 was considered as statistically significant.
OMEGA-3, NUTRITION, INFLAMMATION IN HD PATIENTS 179
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omega-3 supplementation decreased serum concentrations
of TNF-a, IL-6, and CRP, and it increased serum levels of
IL-10 and ratios of IL-10 to TNF-aand IL-10 to IL-6. In
addition, there was an increase in serum iPTH and ferritin
levels, as surrogates of inflammatory state, in both groups
throughout the study period, with much more of an in-
crease in the placebo group. However, nonparametric com-
parison of mean change (post-treatment minus baseline)
between the 2 groups demonstrated a significant difference
exclusively in the IL-10 to IL-6 ratio and the serum ferritin
level (Tab l e 2 ). Moreover, a regression analysis with boot-
strap method showed that omega-3 treatment was a signif-
icant independent predictor of reduced serum ferritin and
iPTH levels and an increased IL-10 to IL-6 ratio when their
post-treatment values were adjusted for their baseline values
and patients’ demographic and clinical data (Ta b le 3 ).
In our study, in comparison with the placebo group,
supplemental use of omega-3 fatty acids did not produce
significant changes in nutrition indices, including BMI,
dry body weight, MAC, and serum transferrin concentra-
tion (Table 2). On the other hand, serum prealbumin con-
centration increased in omega-3-treated patients whereas
its concentration decreased in the placebo group during
the study period. Nonetheless, no significant difference
was observed in the mean change of serum prealbumin
concentration between the 2 groups at the end of the study.
In addition, despite a lack of significant difference in serum
albumin concentration between the 2 groups at baseline,
the mean change in the omega-3 group was significantly
lower than that in the placebo group (P5.018).
Ta b l e 4 depicts statistically significant determinants of
postintervention values of nutrition indices in a linear regres-
sion model. HD vintage had negative associations with post-
intervention BMI and dry body weight (P,.001 for both).
In addition, HD vintage was the sole significant and positive
predictor of postintervention serum transferrin concentra-
tion (P5.005). A significant negative association was also
found between serum albumin concentration and age of pa-
tients (P,.05). Among the nutrition indices measured in
our study, omega-3 treatment was only a significant positive
predictor of serum prealbumin concentration.
To know whether the beneficial effects of omega-3 fatty
acids on serum prealbumin are mediated through their
ameliorative effects on the inflammatory process, serum
prealbumin concentration was adjusted for inflammation
markers in different regression models. Regression analysis
revealed that the ameliorative effect of omega-3 treatment
on serum prealbumin level was closely related to its suppres-
sive effects on serum iPTH level becauseomega-3 treatment
was no longer a significant predictor of postintervention
serum prealbumin level in the presence of iPTH as a covar-
iate in linear regression.
Over the course of the study, omega-3 and placebo cap-
sules were well tolerated without any reports of serious
adverse events. Mild transient gastrointestinal complaints
including nausea, burping, and loose stool were frequently
Table 2. Indices of Inflammation and Nutrition in the Omega-3 and Placebo Groups
Inflammation/
Nutrition Indices
Preintervention Postintervention Change
POmega-3 Placebo Omega-3 Placebo Omega-3 Placebo
IL-6 (ng/L) 144.38 6167.66 97.75 6138.48 136.85 6183.56 106.48 6136.51 27.53 6126.01 2.94 6206.17 .11
TNF-a(ng/L) 122.09 6171.69 77.16 662.47 116.57 6172.32 77.43 659.82 25.52 646.92 23.5 649.21 .97
IL-10 (pg/mL) 123.94 671.91 108.55 664.59 132.06 694.81 107.24 663.01 8.11 657.63 24.51 690.79 .44
IL-10/IL-6 1.32 60.55 1.59 60.41 1.96 61.19 1.39 60.35 0.64 61.14*20.18 60.53 .003*
IL-10/TNF-a1.35 60.29 1.85 61.13 1.44 60.28 1.69 60.95 0.09 60.25 20.17 61.17 .399
CRP (mg/L) 9.24 68.79 7.74 64.68 8.65 67.83 12.69 614.02 21.25 65.68 4.96 612.59 .143
Ferritin
(ng/mL)
893.36 6743.54 356.52 6163.08 997.22 61,105.47 1,236 6885.85 165.45 6886.59*890.05 6862.71 .000*
iPTH (pg/mL) 330.72 6553.69 272.26 6233.51 495.31 6928.55 624.93 61,057.51 14.65 6235.88 383.39 6927.49 .17
Prealbumin
(mg/mL)
380.55 6509.69 258.68 6428.56 414.28 6559.04 151.25 694.71 33.73 6556.27 2122.40 6398.78 .196
Albumin
(g/dL)
4.41 60.82 3.98 60.37 4.01 60.36 4.28 60.48 20.33 60.79*0.34 60.64 .018*
Transferrin
(mg/dL)
222.10 651.72 246.65 686.86 175.50 653.55 185.12 648.39 251.06 655.08 261.21 6104.14 .713
Dry body
weight (kg)
62.16 69.70 64.20 610.11 62.74 69.99 64.80 612.01 0.58 61.99 0.74 63.83 .891
BMI (kg/m
2
) 23.84 63.82 23.29 63.24 24.07 63.91 23.88 64.46 0.23 60.81 0.48 61.51 .892
MAC (cm) 26.32 62.88 24.75 63.68 27.82 66.14 25.83 63.63 1.5 64.16 1.11 62.08 .653
BMI, body mass index; CRP, C-reactive protein; IL, interleukin; iPTH, intact parathyroid hormone; MAC, mid-arm muscle circumference;
TNF-a, tumor necrosis factor-a.
All data are expressed as mean 6SD. Pvalues, pertaining to comparisons of changes between groups, were derived from Mann-Whitney U
test with the exception of transferrin and IL-10/TNF-a, which were derived from unpaired Student’s ttest.
*P,.05 was considered as statistically significant.
GHAREKHANI ET AL180
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the reported side effects and mostly occurred in omega-3-
treated patients.
Discussion
It has been well established that inflammation is a prom-
inent feature of chronic kidney disease in predialysis and
dialysis patients.
13
Proinflammatory comorbid conditions
(e.g., infections, diabetes mellitus, and atherosclerosis),
uremic toxins, modality of dialysis, retained inflammatory
mediators, oxidative stress, insulin resistance, and diet are
several different factors that may contribute to the high
prevalence of inflammation in this patient population.
1,13
Given the established role of chronic inflammation in
developing PEW,
14
interventions with anti-inflammatory
properties may improve the nutritional state of chronic
HD patients. Although HD patients consume inadequate
omega-3 fatty acids
15
and have lower plasma levels of these
fatty acids,
16
no well-established recommendation has been
made on omega-3 supplementation in this population. Our
study examined the potential of omega-3 fatty acid supple-
mentation to improve the nutritional and inflammatory
state of HD patients.
Although a significant difference, in favor of omega-3
treatment, was exclusively observed in the mean change
of serum ferritin and the ratio of IL-10 to IL-6 between
the 2 groups, administration of omega-3 fatty acids also
produced slight desirable changes in serum inflammatory
markers, as evident in the serum concentrations of IL-6,
TNF-a, CRP, IL-10, iPTH, and the IL-10 to TNF-aratio.
Failure to obtain significant anti-inflammatory effects by
omega-3 supplementation in our study may partly be ex-
plained by the relatively small dosage of omega-3 fatty acids
or the short follow-up period. It is important to note that
most of the studies investigating the effects of omega-3 fatty
acids on the inflammatory markers of HD patients are not
comparable because of a wide variation in study design,
supplement dosage, study duration, and the EPA to DHA
ratio. Saifullah and colleagues demonstrated that oral sup-
plementation of 1.3 g of EPA and DHA daily for 3 months
significantly lowered serum CRP levels.
10
Himmelfarb and
colleagues examined the effects of a gamma-tocopherol-
enriched mixture of tocopherols and DHA (providing
924 mg gamma-tocopherol and 1,200 mg DHA per day)
on the inflammation markers of HD patients.
17
After
6 months of supplementation, the serum IL-6 level showed
a significant reduction compared with the baseline value
whereas no significant change was observed in serum
CRP level. In addition, Perunicic-Pekovic and colleagues
found a significant decrease in the serum IL-6 and TNF-
alevels of HD subjects treated with 2.4 g of omega-3 fatty
acids daily for 2 months.
9
Bowden and colleagues showed
that administration of 2 soft-gel capsules of omega-3 sup-
plement with each meal for 6 months (providing a total
of 960 mg EPA and 600 mg DHA per day) produced a sig-
nificant reduction in serum CRP level.
18
On the other
Table 3. Linear Regression Analysis Demonstrating the Effect of Omega-3 Treatment on Postintervention Values of CRP, Ferritin, iPTH, and Cytokines After
Adjustment for Their Baseline Values and Patients’ Demographic and Clinical Data
Independent
variable
Dependent Variable*
Post-IL-6 Post-TNF-aPost-IL-10 Post-IL-10/IL-6 Post-IL-10/TNF-aPost-CRP Post-ferritin Post-iPTH
Omega-3
treatment
Coefficient (b)225.877 26.566 25.389 0.894 20.103 22.789 2922.484 2414.247
Bootstrap
standard error
46.403 11.973 20.366 0.338 0.216 3.022 282.992 213.935
P.577 .583 .791 .008*.633 .356 .001*.053†
95% CI (2147.422, 42.715) (232.778, 14.654) (263.172, 22.849) (0.319, 1.603) (20.672, 0.226) (29.260, 2.417) (21,533.274, 2412.422) (21,150.008, 2129.641)
CI, bias-corrected and accelerated confidence interval; CRP, C-reactive protein; IL, interleukin; iPTH, intact parathyroid hormone; pre-, preintervention; post-, postintervention; TNF, tu-
mor necrosis factor.
*All analyses were adjusted for age, sex, hemodialysis duration, and baseline values of Kt/V and outcome variables.
†P,.05 or 95% CI (with bootstrap method) not including null value was considered as statistically significant.
OMEGA-3, NUTRITION, INFLAMMATION IN HD PATIENTS 181
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Table 4. Regression Analysis Reflecting the Effect of Omega-3 Treatment on Nutrition Indices After Adjustment for Their Baseline Values, Age, Sex, Baseline Kt/V, and
HD Vintage
Dependent
Variable
Independent Variables
Omega-3 Baseline Value Age Sex Baseline Kt/V HD Vintage
Post-albumin b520.18 b50.05 b520.01 b520.01 b520.23 b520.0005
95% CI (20.53, 0.06) 95% CI (20.22, 0.23) 95% CI (20.02, 20.001) 95% CI (20.26, 0.32) 95% CI (20.70, 0.27) 95% CI (20.004, 0.002)
P5.233 P5.645 P5.048*P5.950 P5.350 P5.742
Post-prealbumin b5182.53 b50.54 b522.67 b578.08 b5572.07 b50.89
95% CI (21.14, 511.18)*95% CI (0.13, 0.92)*95% CI (212.29, 5.06) 95% CI (2194.62, 318.25) 95% CI (232.79, 1,159) 95% CI ( 20.88, 3.32)
P5.110 P5.055 P5.519 P5.554 P5.050 P5.402
Post-transferrin b521.31 b50.17 b51.11 b525.35 b5234.26 b50.48
95% CI (236.04, 29.52) 95% CI (20.10, 0.52) 95% CI (20.34, 2.44) 95% CI (246.72, 21.80) 95% CI (296.89, 60.35) 95% CI (0.14, 0.81)
P5.936 P5.274 P5.123 P5.743 P5.374 P5.005*
Post-MAC b50.88 b51.14 b520.03 b51.33 b523.75 b50.01
95% CI (21.27, 4.73) 95% CI (0.61, 2.12) 95% CI (20.15, 0.05) 95% CI (20.60, 4.83) 95% CI (213.67, 0.85) 95% CI (20.01, 0.05)
P5.542 P5.001*P5.537 P5.308 P5.274 P5.596
Post-BMI b520.57 b51.07 b520.02 b520.09 b50.71 b520.01
95% CI (21.34, 0.08) 95% CI (0.94, 1.17) 95% CI (20.05, 0.01) 95% CI (20.80, 0.71) 95% CI (21.01, 2.44) 95% CI (20.02, 20.01)
P5.117 P5.000*P5.141 P5.817 P5.391 P5.000*
Post-dry weight b520.89 b51.09 b520.06 b50.93 b52.73 b520.03
95% CI (22.53, 0.83) 95% CI (0.99, 1.18) 95% CI (20.13, 0.03) 95% CI (20.97, 3.06) 95% CI (22.06, 8.28) 95% CI (20.05, 20.02)
P5.295 P5.000*P5.151 P5.370 P5.253 P5.000*
CI, bias-corrected and accelerated confidence interval; HD, hemodialysis; post-albumin, postintervention albumin; post-BMI, postintervention body mass index; post-dry weight, post-
intervention dry weight; post-MAC, postintervention mid-arm circumference; post-prealbumin, postintervention prealbumin; post-transferrin, postintervention transferrin.
*P,.05 or 95% CI (with bootstrap method) not including null value was considered as statistically significant.
GHAREKHANI ET AL182
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hand, a recent study on HD patients using 2.08 g of omega-
3 fatty acids for 10 weeks failed to exert any effects on serum
CRP, IL-6, and TNF-aconcentration.
19
Consistent with
our findings, Hassan and colleagues reported that omega-
3 supplementation (2.4 g DHA and 1 g EPA per day orally)
to peritoneal dialysis patients for 8 weeks produced an
insignificant decrease in the serum inflammatory markers,
including CRP, IL-6, and TNF-a.
20
Our results were
also in agreement with those obtained by Poulia and col-
leagues, in which supplemental use of omega-3 fatty acids
(1,680 mg per day) for 4 weeks caused an insignificant
reduction in serum CRP levels in chronic HD patients.
21
Furthermore, omega-3 treatment in our study was a signif-
icant and independent predictor of reduced serum ferritin
and iPTH level. With implementing a careful monitoring
during the study period and having free access to intrave-
nous iron sucrose and erythropoietin, it seems that a large
amount of the increase or decrease in serum ferritin level
is related to a systemic inflammatory state in HD patients.
In addition, none of the patients in our study received cina-
calcet to control hyperparathyroidism, and the number of
patients taking calcitriol was comparable between the 2
groups. Taken together, significant association of omega-
3 treatment with reduced serum ferritin and iPTH levels
might reasonably be translated into a relative attenuation
of systemic inflammation after 4 months of omega-3
supplementation.
PEW is involved in a complex syndrome induced by
nutritional and non-nutritional factors such as poor food
intake secondary to uremia, restrictive diets, a persistent in-
flammatory state, enhanced catabolism due to treatment
modalities, loss of nutrients into the dialysate, and meta-
bolic acidosis.
5
Given the importance of the problem, as
well as the complexity of the relationship between chronic
inflammation and PEW, it is obviously conceivable that
preventive and/or therapeutic options would be complex
and critical. To date, no single treatment approach has
been able to successfully alleviate such a complex syndrome
of uremia. We thought that omega-3 fatty acids with a sup-
pressive effect on the inflammatory response might improve
the nutritional state of maintenance HD patients.
We found that the serum albumin level significantly
decreased in the omega-3 group compared with the pla-
cebo group during the study. This finding was in contrast
to what was reported by Perunicic-Pecovic and colleagues,
in which administration of 2.4 g of omega-3 fatty acids daily
for 8 weeks significantly increased the serum albumin level
in chronic HD patients.
9
Kalantar-Zadeh and colleagues
used a novel nutritional oral supplement (containing
1,680 mg omega-3 fatty acids) during each HD session
for 4 weeks to improve the nutritional status of HD pa-
tients.
7
In contrast to our finding, a significant increase
appeared in the serum albumin concentration and total
iron binding capacity, an important surrogate of serum
transferrin, after 4 weeks of intervention. Although our
study used a relatively higher dose of omega-3 supplement
(1,800 mg per day) for a longer period (4 months), we
could not compare our results with those of Kalantar-
Zadeh and colleagues because the different composition
of the supplement given in their pilot study made it impos-
sible to distinguish the potential benefits of omega-3 fatty
acids from other constituents. Vernaglione and colleagues
observed no change in the serum albumin level of chronic
HD patients after 4 months of supplemental use of
2,100 mg of omega-3 fatty acids.
22
In addition, and in
agreement with our finding, Mat Daud and colleagues
failed to indicate a significant improvement in the nutrition
indices of maintenance HD patients, including BMI,
malnutrition-inflammation score, normalized protein
equivalence of nitrogen appearance, and serum albumin
level, when subjects were given 30 mL of liquid protein
supplement (providing 18 g protein) combined with 4
omega-3 capsules (providing a total of 1,800 mg EPA and
600 mg DHA) during regular dialysis sessions for
6 months.
5
In our study, the observed discordance of reduced serum
albumin level with slight attenuation of inflammatory state
may be explained by the results of some previous studies.
Kaysen and colleagues showed that serum albumin, as a sur-
rogate of protein intake, is not an exclusive correlate of
inflammation.
23
Friedman and Fadem proposed that serum
albumin should be considered as a marker of illness rather
than nutrition.
24
On the other hand, in this study, regres-
sion analysis adjusting post-treatment serum albumin for
demographic factors revealed a marginally significant and
negative association between serum albumin and patients’
age. This finding may be explained by the poor food and
energy intake of HD patients with aging as illustrated by
other researchers.
25
Altogether, difficulty in interpreting
our finding might partly be because serum albumin is influ-
enced by other nutritional and non-nutritional factors that
were not controlled in our study. Thus, future studies
should consider other potential confounding factors.
In the study presented here, we found no significant
changes in dry body weight, BMI, MAC, and serum con-
centrations of transferrin and prealbumin in the omega-3
group compared with the placebo group. These results are
consistent with those obtained by Szklarek-Kubicka in
that they also found no significant effects of intradialytic
intravenous administration of omega-3 emulsion (providing
2 g EPA and 2 g DHA) on BMI and serum concentrations
of albumin and transferrin after 11 consecutive HD ses-
sions.
26
On the other hand, Ewers and colleagues showed
a significant increase in the body weight of HD patients
who were given a dietary supplement providing 3 g of
omega-3 fatty acids per day for 6 weeks.
4
In agreement
with our results, no significant changes were observed in
the nutritional parameters of HD patients, including BMI,
when Moreira and colleagues treated them with a sardine
supplement (containing 3.87 g omega-3 fatty acids) during
OMEGA-3, NUTRITION, INFLAMMATION IN HD PATIENTS 183
Author's personal copy
each HD session, thrice weekly, for 8 weeks.
12
In our study,
although the increased serum prealbumin level in omega-3
group did not reach statistical significance versus the placebo
group, regression analysis revealed that omega-3 treatment
was a significant independent predictor of increased serum
prealbumin level. According to the fact that serum prealbu-
min is a sensitive nutrition marker with the shortest serum
half-life among serum nutrition markers measured in this
trial, we might likely find significant improvement in serum
prealbumin with a larger dose of omega-3 and/or a some-
what longer intervention period.
In our study, adjusted regression analysis illustrated that
among patients’ demographic and clinical data, HD dura-
tion was a significant independent predictor of decreased
dry body weight and BMI. In line with our finding, a 9-
year longitudinal study on HD patients by Mekki and col-
leagues showed a negative significant correlation between
BMI and HD duration.
27
It is a wise thought that decreased
energy and food intake in prolonged HD treatment may
contribute to reduced BMI and body weight in this popu-
lation. On the contrary, HD duration showed a positive sig-
nificant association with serum transferrin concentration in
this study. Although positive correlation between serum
albumin and HD duration has been reported in previous
studies,
9
we failed to find such relationship between trans-
ferrin and the duration of HD treatment in the literature.
However, a recent study by Formanowicz and colleagues
noted that transferrin variant 3, likely a crucial variant in
iron transport, was positively associated with the duration
of HD treatment in the presence of a worsened inflamma-
tory state.
28
We were unfortunately not able to know which
of the transferrin variants comprised the dominant variant
of measured serum transferrin.
As evident in Table 4, among the nutrition indices
measured in this trial, serum prealbumin was the exclusive
marker correlated significantly and positively with the
omega-3 treatment. Serum iPTH level was the sole inflam-
mation marker that largely contributed to improvement of
serum prealbumin level by omega-3 treatment. Adding to
the difficulty in interpreting this finding may be the rela-
tively less clear role of iPTH in the inflammatory processes
and the paucity of studies on the relationship between
iPTH and inflammation.
Although the usefulness of omega-3 supplementation to
improve the nutritional and inflammatory state of HD pa-
tients was not remarkable in our study, there were several
strengths to our trial, including the placebo-controlled
design, the relatively longer follow-up period (4 months),
the relatively comprehensive evaluation of nutrition and
inflammation state of HD patients, no serious adverse
events leading to patient withdrawal, and more frequent
interviews with patients to enhance their compliance.
However, we admit some limitations, which should be
considered in the interpretation of the results. There was
low statistical power to detect meaningful differences be-
tween groups because of the small population size. As ex-
amples, to detect difference between 2 groups regarding
mean changes of serum CRP, IL-10, and prealbumin at
an alevel of 0.05 and a power of 80%, approximately 39,
570, and 150 patients in each group were respectively
required. The length of our study seemed to be shorter
compared with some previous studies. We used the con-
ventional practice of ‘‘pill counting’’ to monitor patient
compliance rather than measurement of erythrocyte mem-
brane fatty acid composition as the standard compliance
measurement. Our study lacked an interim analysis to
follow a potential trend over time and lower variance of es-
timates of treatment effects. The ‘‘fishy’’ smells of omega-3
capsules, although not mentioned as a complaint by any
patients, did not appear in placebo capsules, which might
have affected the blindness of subjects in the placebo arm
of the study. Finally, the assessment of the nutritional state
of patients did not include their dietary intake as a potential
confounder to our intervention.
In conclusion, our study showed that a 4-month admin-
istration of omega-3 fatty acids in chronic HD patients was
well tolerated and useful in regard to the relative attenuation
of systemic inflammation. Although omega-3 supplemen-
tation failed to produce pronounced alleviation in systemic
inflammation, its positive, although slight, effects on
inflammatory state were encouraging by considering sys-
temic inflammation as a correlate of increased cardiovascu-
lar mortality in maintenance HD patients. Given the lack of
any remarkable effects of omega-3 fatty acids on nutritional
parameters, it can be speculated that additional nutritional
support, along with omega-3 supplementation, might pre-
vent/treat PEW in maintenance HD patients. However, we
propose further well-designed investigations to definitely
determine the effectiveness of omega-3 fatty acids in
improving the nutrition and inflammatory state of HD
patients.
Practical Application
Considering the cardiovascular benefits of continuous
dietary ingestion of omega-3 fatty acids as a minimum, their
continuous consumption coupled with nutritional support
seems to be beneficial in improving the malnutrition-
inflammation complex in maintenance HD patients.
Acknowledgments
This study was supported by Tehran University of Medical Sciences
(grant no. 17020). The authors thank Zahravi Pharmaceutical, Co., Teh-
ran, Iran, for providing placebo free of charge and Dr. Amir Hekmat for
his kind coordinating between the researchers’team and the pharmaceu-
tical company. The authors also appreciate the valuable help of the HD
nursery teams of the Imam-Khomeini Hospital complex and Sina Hospi-
tal, especially Mrs. Abdpoor.
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