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Correlation Between Dietary Zinc Intakes
and Its Serum Levels with Depression Scales in Young
Female Students
Reza Amani &Somaye Saeidi &Zahra Nazari &
Sorour Nematpour
Received: 19 September 2009 /Accepted: 12 November 2009 /
Published online: 15 December 2009
#Springer Science+Business Media, LLC 2009
Abstract It has been suggested that mood disorders and depressive status may be
accompanied by lowered zinc status in the body, and adequate consumption of zinc increases
a general perceived well-being. The main objective of this study was to assess the correlation
between serum zinc concentrations and dietary zinc intakes with depression scores in
university female students. In the first phase, Beck's depression questionnaire was applied in
a random sampling of 308 selected 20–25-year-old female students (one third of total
students in Ahvaz Jondi-Shapour University of Medical Sciences Golestan dormitories) to
assess the major depressive disorder (MDD) scales. Then, in the second phase, 23 students
who identified as having moderate and severe depression were selected as the case group,
and 23 healthy age matched were chosen as the controls. Each of them completed a 12-item
semiquantitative food frequency questionnaire containing the main food sources of zinc in
the usual dietary patterns and also a 24-h food recall questionnaire to assure the daily zinc
intakes. Daily zinc intakes were obtained by multiplying each portion size by its zinc
content using food tables. A 5-ml blood sample was taken for further serum zinc status
using flame atomic absorption spectrophotometry technique. Pearson's rwas used to show
the correlation between quantitative variables. Both daily zinc intake and serum zinc
concentrations of MDD group were about two thirds of healthy index (p<0.01). Depressed
individuals used to eat lower servings of red meats and chicken as the main food sources of
zinc in students' usual diets (p<0.001). Consumption of other foods as the sources of zinc
was not significantly different in two groups. A linear significant correlation between
Biol Trace Elem Res (2010) 137:150–158
DOI 10.1007/s12011-009-8572-x
R. Amani (*):S. Saeidi
Department of Nutrition, Faculty of Paramedicine, Diabetes Research Center,
Jondi-Shapour University of Medical Sciences, Ahvaz, Iran
e-mail: rezaamani@hotmail.com
Z. Nazari
Department of Toxicology & Pharmacology, School of Pharmacy,
Jondi-Shapour University of Medical Sciences, Ahvaz, Iran
S. Nematpour
Department of Clinical Psychology, Golestan Medical Center,
Jondi-Shapour University of Medical Sciences, Ahvaz, Iran
dietary zinc intakes and its serum levels was seen in samples (r= 0.62; p< 0.001) and MDD
students (r=0.55; p<0.001). There was a linear inverse correlation between Beck
questionnaire scores and serum zinc concentrations in all of the investigated students
(r=-0.65; p<0.001) and MDD girls (r=−0.71; p<0.001). Beck questionnaire scores and
diatary zinc intakes were also inversly correlated (r=−0.58; p<0.001). However, no
statistical correlation was seen between these two variables in MDD cases. In depressed female
students, dietary zinc intake is correlated to its serum concentrations; however, the serum zinc
levels are inversely correlated to depression scales. Consumption of the main dietary sources of
zinc such as red meats and chicken should be encouraged in young depressed girls.
Keywords Zinc .Nutrition .Depression .Female students
Introduction
Depression is a psychiatric disorder with high morbidity and mortality. It is estimated that
depression is the cause of 50–70% suicides [1]. The World Health Organization predicts
that depression will be the second most important cause of human disability—adjusted life
years by the year 2020 [2].
During the last several years, many articles have been presented indicating important
role of zinc in the psychopathology and therapy of depression. Zinc is a trace element,
essential for living organisms.
More than 300 enzymes require zinc for their activities. Zinc plays an important role in the
DNA replication, transcriptions, and protein synthesis, influencing cell division and
differentiation [3]. Dietary zinc deprivation retards growth of human and animal organisms
[4]. The highest amount of zinc is present in the brain, especially in the hippocampus and
cerebral cortex [3,5]. Zinc deprivation influences brain zinc homeostasis and leads to
alteration in behavior, learning, mental function, and susceptibility to epileptic convulsions [4].
Zinc, as an antagonist of the glutamate/N-methyl-D-aspartate receptor, exhibits
antidepressant-like activity in rodent tests/models of depression. Similar to antidepressants,
zinc induces brain-derived neurotrophic factor (BDNF) gene expression and increases level of
synaptic pool of zinc in the hippocampus. Clinical observations demonstrated serum
hypozincemia in depression, which was normalized by effective antidepressant treatment [6].
Recent results show that chronic treatment with antidepressants and electroconvulsive
shock induces an increasing in zinc concentrations in the rat brain. Calculation of the
hippocampus/brain region zinc concentration ratio within groups treated with antidepres-
sants (such as citalopram or imipramine) demonstrated a significantly higher value after
treatment with both drugs [7].
On the other hand, women of childbearing age are at high risk for major depressive
disorder (MDD). The lifetime risk for MDD in community samples has varied from 10% to
25% for women, with peak prevalence between 25 and 44 years old [8].
In Iran, studies conducted by the Ministry of Health at national level have concluded that
prevalence of zinc deficiency in females living in southwest of Iran (including city of
Ahvaz) is about 20% based on serum zinc levels [9].
MDD is a leading cause of disease-related disability among women worldwide [8].
During this century, MDD is occurring earlier in the life span in successive generations;
therefore, an increasing number of women will become ill during their childbearing years.
MDD is underrecognized and undertreated in clinical settings [10]. If depression is
appropriately diagnosed, the high cost and side effects of antidepressants remain important
Correlation Between Dietary Zinc Intakes and Its Serum Levels with Depression Scales... 151
treatment barriers for many women [11,12]. Although, not all depressed women respond to
drug treatment, the additional therapies would be needed [13].
Given the public health importance of MDD and the ubiquitous problem of poor diet
quality, and also historic prevalence of zinc deficiency in some subsamples of Iranians [14],
our objective was to evaluate the current status of serum levels and dietary intake of zinc in
a sample of depressed young girls and to address implications for women of childbearing
age.
Methods
Subjects In the fall and winter 2006, as the first setp of study, a 21-question Beck's
questionnaire [15] was applied to assess the MDD scales in a sample of 308 female students
in the range of 20–25 years old. Scores below 9, 10–18, 19–29, and 30–63 were regarded as
normal, mild, moderate, and severe depression, respectively.
They were one third of total girls living in Ahvaz Jondi-Shapour University, Golestan
dormitory complex. Jondishapour University is one of the eight main class-A National
Iranian Medical Universities which is located in city of Ahvaz, Khuzestan provience, north
of the Persian Gulf.
In the second phase, 23 students were selected and defined as having moderate to severe
depression (scores higher than 19) as the MDD group and 23 age-matched student with no
history of any mood deprivations assigned as controls.
Dietary Assessment For evaluating both qualitative and quantitative dietary patterns, all 46
samples completed a 12-item semiquantitative food frequency quetionnaire containing the
main dietary sources of zinc in food groups consumed according to the students' daily and
weekly patterns. However, four food items including shrimp, river fishes, shelfishes, and
nuts (except soy nut and peanut) were not reported in the students' usual dietary patterns so
they were excluded in analysis. They also completed a 24-h food recall questionnaire to
assure the amount of daily zinc intake. After multiplyng zinc contents in each food item by
its portion size, daily zinc intakes were reported as milligrams per day using Nutritrack 3®
software, USA. The database of this software was used for evaluating zinc contents of each
food items. All data were recorded through direct interviews carried out by three trained
senior nutrition students. All subjets followed their daily meals provided by the university
self-service as a weekly constant meal program.
Serum Zinc Status Each of 46 individuals in both groups gave 5-ml blood sample for
further laborotary measurements. Serum zinc concentrations of samples were measured by
fivefold diluting them, aspirating into the atomic absorption flame, and comparing the their
signals with the those from aqueous calibrators, which was prepared in the diluted glycerol
(5 ml/dL). Instrument was Chemtech, model CTA 3000, made in England, by setting
wavelength for reaout absoption 213.9 nm and slit width 0.7 nm. Serum zinc levels lower
70 μg/dL was regarded as deficiency [16].
Statistics Kolmogrov–Smirnov test was applied to show normal distribution of variables.
Independent ttest was conducted to compare variables means between groups. Pearson's r
was used to illustrate linear correlation between continious quantitative variables using
SPSS® software version 13. To compare consumption of the food categories between
groups, chi-square test was applied. pvalue less than 0.05 was regarded as significant.
152 Amani et al.
Medical Ethics All students gave their written consents, and no name was disclosed in the
results. Medical Ethics Committee of Jondi-Shapour Univerity of Medical Sciences
approved the protocol of study.
Results
Table 1shows no significant diference between mean age of two groups. Both daily zinc
intake and serum zinc concentrations of MDD group were about two thirds of healthy
samples (p<0.001). Evaluation of dietary patterns (Table 2) showed that affected
individuals used to consume lower servings of red meats and chicken as the main food
sources of zinc in students' usual diets (p<0.001) However, there was no significant
diference in consumption of other dietary zinc sources between study groups (eight items
were answered as the main dietary usual zinc sources on both daily and weekly basis;
Table 2).
Figures 1and 2indicate a linear regression between dietary zinc intakes and serum zinc
levels in all samples (r=0.62; p<0.001) and MDD students (r=0.55; p<0.001),
respectively. Figures 3and 4show a linear negative regression between Beck questionnaire
scores and serum zinc concentrations in all subjects (r=−0.65; p<0.001) and MDD girls
(r=−0.71; p<0.001), respectively.
There was also an inverse correlation between Beck questionnaire scores and diatary
zinc intakes (milligram per day) in all subjects (r=−0.58; p< 0.001; Fig. 5). However, no
statistical correlation was seen between these two variables in MDD subjects.
Discussion
Zinc has the second highest concentration of all transition metals after iron in the brain [17].
Most zinc is localized within synaptic vesicles of specific neurons, where it is thought to
modulate synaptic transmission and may itself act as a neurotransmitter [3,17]. Clinical
manifestations of zinc deficiency include behavioral disturbances such as anorexia
dysphoria, impaired learning and cognitive function, some neurological disorders (e.g.,
epilepsy, Alzheimer's disease), and depression [17–22].
In the present study, it was shown that both serum zinc levels and dietary zinc intakes in
depressed girls were lower (about two thirds) compared with their healthy counterparts
(Table 1). Furthermore, we found that 23 percent of depressed—but no one of healthy
subjects—had serum zinc concentrations below 70 μg/dL (data not shown) which is
indicated as the cutoff point of zinc deficiency [20].
Table 1 Basic Characteristics of Study Groups
Criteria Healthy (n=23) Depressed (n=23) pvalue
Age (year; mean± SD) 20.2± 0.9 20.7± 1.6 0.9
Dietary zinc intake (mg/dL; mean± SD) 2.93± 0.9 1.97± 0.5 <0.001
Serum zinc concentration (mg/dL; mean± SD) 111.6±21.9 79.6± 30.7 <0.001
Beck scores (mean± SD) 2± 1.2 47.2± 17.3 <0.001
SD standard deviation
Correlation Between Dietary Zinc Intakes and Its Serum Levels with Depression Scales... 153
Both Hansen et al. and McLoughlin have reported that blood zinc concentrations are
lower in individuals with MDD compared with control ones [20,21]. Maes and colleagues
studied serum zinc in 48 unipolar MDD patients and 32 control individuals and found that
zinc concentrations were correlated with severity of depression [23].
As the main cause of different dietary zinc intakes between groups, the intake of red
meat and chicken was shown to be more than seven times higher than in controls. However,
it is worthy to note that all girls in two groups had considerably low daily zinc intake which
had been indicated more than four decades ago in Fars province, southwest of Iran [14]. No
similar results regarding dietary zinc intakes and consumption of its food sources in
depressed girls were found in the literature.
Marcellini et al. in their study on zinc status and psychological and nutritional
assessment in old people recruited in five European countries (ZINCAGE project) showed
that all psychological variables (Mini Mental State Examination, the Geriatric Depression
Scale, and the Perceived Stress Scale) were related to plasma zinc values and nutritional
assessment. In particular, a relationship between marginal zinc deficiency and impaired
Table 2 Consumption of the Main Dietary Sources of Zinc in Students' Usual Diets
Food items Servings
a
Healthy n(%) Depressed n(%) pvalue
Red meats (beef) 3–4 times/week 14 (60.8) 2 (8.7) <0.001
Chicken 3–4 times/week 15 (65.2) 2 (8.7) <0.001
Liver 2–3 times/month 23 (100) 20 (87.6) 0.7
Fish 2–3 times/month 23 (100) 22 (95.6) 0.8
Eggs 3–4 times/week 21 (91.3) 20 (87.6) 0.7
Legumes 3–4 times/week 23 (100) 23 (100) 0.9
Soy nuts 3–4 times/week 16 (69.5) 15 (65.2) 0.7
Peanut 2–3 times/month 20 (87.5) 18 (78.3) 0.6
The zinc content of each item in software database is varied due to different varieties, and in most items, we
chose an average amount
a
Servings denote the portion sizes in each food item
Daily zinc intake (mg/day)
6543210
Serum zinc concentrations (ug/dL)
180
160
140
120
100
80
60
40
20
0
Fig. 1 Correlation between
dietary zinc intakes (milligram
per day) and its serum concen-
trations (microgram per deciliter)
in all subjects studied (r=0.62;
p<0.001)
154 Amani et al.
psychological dimensions occurred in Greece than in compare with other European
countries due to low intake and less variety of rich of zinc foods. They concluded that this
phenomenon was independent by the age, suggesting that a correct zinc intake from a wide
range of foods may be useful to maintain a satisfactory plasma zinc levels as well as
psychological status in elderly with subsequent achievement of healthy aging [24].
For further assessment of the correlation between serum zinc concentrations and its
dietary intake, it was found that a linear correlation exists between these variables in all
students and also in depressed subjects (Figs. 1and 2).
In the present study, it has been documented that there is a statistical negative correlation
between Beck's depression scores and serum levels and in all students and depressed girls.
However, the correlation was stronger in the latter group (r=−0.65 vs. r=−0.71).
Notably, to illustrate the correlation between dietary zinc intake and its serum levels and
also their correlations with depression scores, it is necessary to conduct researches with
more number of samples in larger scales.
Serum zinc concentrations (u
g
/dL)
180160140120100806040200
Beck score
70
60
50
40
30
20
10
0
-10
Fig. 3 Correlation between
Beck scores and serum zinc con-
centrations (microgram per deci-
liter) in all subjects studied
(r=−0.65; p<0.001)
Daily zinc intake (m
g
/day)
3.53.02.52.01.51.0.5
Serum zinc concentrations (ug/dL)
160
140
120
100
80
60
40
20
0
Fig. 2 Correlation between
dietary zinc intakes (milligram
per day) and its serum concen-
trations (microgram per deciliter)
in MDD subjects (r=0.55;
p<0.001)
Correlation Between Dietary Zinc Intakes and Its Serum Levels with Depression Scales... 155
Zinc supplementation in depressed people is one of the critical suggestions remained to
be more clarified. Previously, Nowak and his colleagues [25] had shown that their study on
unipolar depressed subjects is the first demonstration of the benefit of zinc supplementation
in antidepressant therapy, and in a newer review, Levenson has introduced zinc as a new
antidepressant [26]. In another study, Sowa-Kućma et al. evaluated the antidepressant
activity of zinc in a chronic mild stress (CMS) model of depression and the effect of zinc
treatment on BDNF protein and the messenger RNA level. In CMS, zinc hydroaspartate
(10 mg/kg) exhibited a rapid (after 1 week of treatment) antidepressant-like effect [27].
Although more researches are needed to clarify the role of nutrition in the
pathophysiology of MDD among young women, clearing the potential for dietary
modification to improve mental health is compelled. Moreover, assessment of antioxidants,
selenium, and iron status along with zinc is suggested because these nutrients have received
less attention in the literature but hold substantial promise in modulating mood [28].
Confounders and effect modifiers of the nutrition–MDD relation, including socioeconomic
Serum zinc concentrations (u
g
/dL)
160140120100806040200
Beck score
70
60
50
40
30
Fig. 4 Correlation between
Beck scores and serum zinc con-
centrations (microgram per
deciliter) in MDD subjects
(r=−0.71; p<0.001)
Daily zinc intake (m
g
/day)
6543210
Beck score
70
60
50
40
30
20
10
0
-10
Fig. 5 Correlation between
Beck scores and diatary zinc
intakes (milligram per day) in all
subjects studied (r=−0.58;
p<0.001)
156 Amani et al.
status, race/ethnicity, parity, body mass index, access to health care, physical activity, and
dietary supplement use, should be measured and addressed in the analysis.
Nutrition interventions are relatively inexpensive, easy to administer, and generally
acceptable to patients. Indeed, nutritional modification may benefit psychiatric conditions
and countless aspects of human well-being, as well as have the potential for tremendous
public health/nutrition impact.
Acknowledgment This research was an approved University Project no. U 86070 and its costs were
covered by the United Nations University grant. The authors wish to appreciate senior nutrition students Miss
S. Andayesh, Miss A. Raeisi, and personnels of Analytical Lab of Pharmacy School, Mrs. R Ebrahimi and
Mrs. A Hosseini, for their kind cooperations.
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