A model for the role of the proline-linked pentosephosphate pathway in phenolic phytochemical biosynthesis and mechanism of action for human health and environmental applications
Author:Kalidas ShettyPhD and Mark Wahlqvist AO, MD, FRACP
Keywords:antioxidant response, antimicrobials, chronic disease, environmental applications, human health, oxidation-linked disease, oxidative phosphorylation, phenolic antioxidants, phytochemicals, proline-linked pentose phosphate pathway
Abstract:The combination of immunodeficiency, inflammatory process and nutritional status that is characteristic of infective
and food-borne illness is more evident in chronic diet- and environment-influenced chronic diseases such as diabetes,
obesity, cardiovascular disease, cancer, arthritis and neuro-degeneration diseases. These chronic diseases tend to be
oxidation-linked and may manifest in communities around the world, irrespective of income. In addressing the
challenges of the above diseases, a significant role for dietary phytochemicals is emerging. Phytochemicals are
required from a spectrum of food for at least their antioxidant role, if not for other properties, to protect tissues from
activities that manifest themselves into what we call chronic disease. Among the diverse groups of phytochemicals,
phenolic antioxidants and antimicrobials from food plants are being targeted for designed dietary intervention to
manage major oxidation-linked diseases such as diabetes, cardiovascular diseases, arthritis, cognition diseases and
cancer. Foods containing phenolic phytochemicals are also being targeted to manage bacterial infections associated
with chronic diseases such as peptic ulcer, urinary tract infections, dental caries and food-borne bacterial infections.
Plants produce phenolic metabolites as a part of growth, developmental and stress adaptation response. These stress
and developmental responses are being harnessed to design consistent phytochemical profiles for safety and clinical
relevancy using novel tissue culture and bioprocessing technologies. The biochemical strategy for harnessing
phenolic phytochemicals for human health and wellness is based on the hypothesis that phenolic metabolites in plants
are efficiently produced through an alternative mode of metabolism linking proline synthesis with pentose-phosphate
pathway. In this model, stress-induced proline biosynthesis is coupled to pentose-phosphate pathway, driving the
synthesis of NADPH2
and sugar phosphates for anabolic pathways, including phenolic and antioxidant response
pathways, while simultaneously providing reducing equivalents needed for mitochondrial oxidative phosphorylation
in the form of proline as an alternative to NADH from Krebs/TCA cycle. Based on this model, tissue culture
techniques and elicitation concepts have been used to stimulate phenolic metabolites with an antioxidant response in
germinating seeds, sprouts and clonal lines of dietary plants. From our initial investigations, a model has been
proposed in which the proline-linked pentose-phosphate pathway is suggested to be critical for modulating protective
antioxidant response pathways in diverse biological systems, including biochemical and cellular pathways important
for human health. The proposed proline-linked pentose-phosphate pathway model provides a mechanism for
understanding the mode of action of phenolic phytochemicals in modulating antioxidant pathways and provides
avenues by which dietary approaches may manage oxidation-linked chronic and infectious diseases. The model also
has implications for the development of antimicrobial phenolic phytochemicals against bacterial pathogens in an era
of increasing antibiotic resistance. Further, this model also has relevance for improving fungal and yeast-based food
bioprocessing for designing functional foods and for environmental bioremediation using plant and microbial
systems, as well as for improving agricultural and food systems in harsh environments.
Asia Pac J Clin Nutr. 2004;13(1):1-24.doi:
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Glutamine: metabolism and application in nutrition support
Author:Jane Coster Grad Dip Diet, Rosalie McCauley PhD an
Keywords:amino acids, glutamine, enteral nutrition, parenteral nutrition
Abstract:Glutamine is the most abundant free amino acid in the body. It is avidly consumed by rapidly dividing cells,
such as those lining the gut, because its 5-carbon skeleton can provide energy whilst the nitrogen molecules
support the synthesis of nucleic acids. Patients who are maintained using conventional solutions of parenteral
nutrients become depleted in glutamine, which has led to the reclassification of glutamine as a conditionally
essential nutrient. Unfortunately, glutamine is unstable in solution and produces toxic byproducts on
decomposition. This means that solutions of nutrients containing glutamine have a relatively short half-life,
which has led to the commercialisation of stable dipeptides containing glutamine. Although it is evident that
glutamine enhances nitrogen metabolism, there is a lack of consistent evidence from the initial clinical trials
demonstrating that supplementation with glutamine has specific clinical advantages. The next few years will
witness the performance of larger scale clinical trials and the results of these studies should define a more
certain role for glutamine in routine clinical practice.
Asia Pac J Clin Nutr. 2004;13(1):25-31.doi:
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Food fears: a national survey on the attitudes of Australian adults about the safety and quality of food
Author:Peter WilliamsBSc(Hons) DipNutrDiet MHP PhD , Emma
Keywords:food safety, additives, pesticides, food labels, Australia
Abstract:A national telephone survey of a representative sample of 1200 Australian adults was conducted in March 2002
in order to identify the factors of greatest concern to consumers in relation to the safety and quality of food, to
measure recent trends in views about hazards in the food supply, to explore beliefs about the safety of additives
and to discover whether consumers use food labels to check for ingredients of concern. Forty five percent of
Australians responded that they were more concerned about the safety and quality of food than they were five
years previously, while only 5% were less concerned. The most common potential hazards volunteered were
additives and chemical residues (28%), followed by food processing/handling/freshness (21%), food hygiene or
contamination (14%), and also genetic modification (14%). More than half of the respondents believe that
additives and preservatives are harmful to your health and that many foods contain high levels of pesticides. A
greater proportion of consumers claimed to be conscious of checking for additives, either general or specific,
on food labels than for information on the salt or sugar content of products. Food regulators, journalists, the
food industry and health professionals need to work together to correct misconceptions about the risks to health
posed by common food additives and pesticide residues.
Asia Pac J Clin Nutr. 2004;13(1):32-39.doi:
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Food consumption patterns in the economic transition in Vietnam
Author:Le Ngoc DienMD, MPH, Nguyen Minh ThangPhD and Marg
Keywords:food consumption patterns, energy intake, economic transition, nutrition transition, Vietnam
Abstract:This paper investigated Vietnamese food consumption patterns, in terms of food quantity and total energy
intake, and examined how these food patterns differ by demography and socio-economic status for the
Vietnamese. Data used in this paper were from the Vietnam Living Standards Survey national cross-sectional
study in 1997-1998. Descriptive and regression analyses identified different food consumption patterns among
5,999 participating households. Results showed that the traditional diet in Vietnam is high in carbohydrates
and low in fat; together with unaccounted eating-out foods, these dietary patterns may contribute to the
population's low energy intake. The regression models identified place of residence, family income, household
size, education of the head of household, ethnicity, and ecological region to be significantly associated with
energy intake. Socio-economic and demographic status must be considered in developing national strategies
and implementing plans of action to improve nutrition.
Asia Pac J Clin Nutr. 2004;13(1):40-47.doi:
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Iron status and dietary iron intake of adolescents from a rural community in Sabah, Malaysia
Author:Leng Huat Foo MSc, Geok Lin Khor PhD, E-Siong Tee
Keywords:iron status, dietary iron intake, iron deficiency anaemia (IDA), female adolescents, Sabah, Malaysia
Abstract:Iron deficiency anaemia (IDA) is the most prevalent micronutrient deficiency in the world affecting the general
health and wellbeing of millions. In Malaysia, moderately high prevalences of anaemia have been reported
amongst infants, young children and women of childbearing age. Data is scant for the adolescents. This study
was undertaken to assess the iron status and dietary intake of 165 adolescents, comprising 74 male and 91
female subjects, aged 12 to 19 years, from the rural communities in Tuaran District of Sabah, Malaysia.
Convenience sampling was used for the selection of study subjects. Multiple iron status indicators namely,
serum ferritin (SF), transferrin saturation (TS), mean corpuscular volume (MCV) and haemoglobin (Hb) were
determined for the study. The mean age of the subjects was 15.2 ±2.1 years. While the majority of the subjects
(77.6%) had normal body mass index (BMI) values, 17.6% were underweight and 4.8% overweight. About
35% to 40% of the subjects showed deficient values for haematocrit, serum ferritin, serum iron, mean
corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and transferrin saturation (TS), and 20%
were anaemic (Hb <12 g/L). Using the multiple criteria of iron status indicators, the prevalence of iron
depletion, iron deficiency and IDA in the male and female adolescents were 5.4% vs. 6.6%, 18.9% vs. 26.4%
and 5.4% vs. 26.4%, respectively. Iron deficiency anaemia (85.0%) contributed largely to the prevalence of
anaemia. The dietary iron intake of the adolescents was unsatisfactory, with approximately 98% of subjects
failing to meet the Malaysian RDA level. Almost all the female subjects (91%) had dietary iron intake below
two-thirds of the RDA level compared with a much smaller proportion for the male adolescents (68%). The
prevalence of IDA in the present study population, especially in the female adolescents, appears to be a
significant public health problem. Priority should therefore be given to the eradication of iron deficiency in
adolescents from low-income areas by dietary modification and micronutrient supplementation amongst female
adolescents.
Asia Pac J Clin Nutr. 2004;13(1):48-55.doi:
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Dietary diversity score in adolescents - a good indicator of the nutritional adequacy of diets: Tehran lipid and glucose study
Author:Parvin Mirmiran MSc, Leila Azadbakht MSc, Ahmad Es
Keywords:dietary diversity, food variety, nutritional adequacy, adolescent, Tehran lipid and glucose study, Iran
Abstract:The purpose of this study was to determine dietary diversity and its relation to dietary adequacy in 10-18 yearold adolescents of district 13 of Tehran during the period 1999-2001. After excluding for over and under
reporters, dietary intake assessment was conducted on 304 , 10-18 year old individuals, participants of Tehran
Lipid and Glucose Study. A dietary diversity score was calculated as part of the pyramid serving database that
is categorized into 23 broad food groups. Each of the 5 broad food categories received a maximum diversity
score of 2 of the 10 possible score points. To be counted as a “consumer” for any of the food groups categories,
a respondent needed to consume one-half serving, as defined by Food Guide Pyramid quantity criteria, at any
time during a 2-day survey period. The nutrient adequacy ratio for a given nutrient is the ratio of a subject’s
intake to the current recommended allowance for the subject’s sex and age category. Weight and height were
measured and BMI was calculated. Student’s t-test was used to compare the means. Those variables which had
normal distribution were tested by Pearson correlation coefficient and the others were tested by the Spearman
correlation coefficient. Mean ± SD of dietary diversity score (DDS) was 6.25 ± 1.08 (range 0-10). The
maximum and minimum scores of dietary diversity were related to the fruit (1.46 ± 0.61) and bread-grain (0.95
± 0.27) groups, respectively. Significant positive correlation was observed between DDS and the mean
adequacy ratio (MAR) (r = 0.42, P<0.001). Fifty percent of people had DDS ≥6. In people with a DDS of six
or over, BMI was higher (19.81 ± 4.08 vs 18.95 ± 3.30 Kg/m
2
, P<0.01) than others. There was a significant
and positive correlation between DDS and most of the nutrient adequacy ratios (NARs). It is concluded that
DDS is an appropriate method to evaluate nutrient intake adequacy in this group of adolescents.
Asia Pac J Clin Nutr. 2004;13(1):56-60.doi:
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Nutritional status of women in Bangladesh: comparison of energy intake and nutritional status of a low income rural group with a high income urban group
Author:Md Zahirul Islam PhD, Mohammed AkhtaruzzamanPhD an
Keywords:anthropometry, body composition, energy intake, socio-economic groups, women, Bangladesh
Abstract:This study evaluated the influence of socio-economic status on energy intake (EI), anthropometric characteristics and body composition (BC) of premenopausal Bangladeshi women in two socio-economic groups. This
cross-sectional study measured height, weight, biceps and triceps skinfolds by standard procedures. A threeday dietary record was used to estimate EI. The biceps and triceps skinfolds were used to calculate total body
fat (TBF), fat-free mass (FFM) and body fat percentage (BF%) according to Durnin and Womersley.
39
FAO/WHO/UNU
15
equations were used to calculate basal metabolic rates (BMR). Two locations in
Bangladesh were studied; the Dhaka city area and the west region of the subdistrict Nandail (Betagair Union)
in the district of Mymensingh. Study subjects were premenopausal women (N =191) aged 16−40 years. The
high socio-economic group (group H, N =90) consisted of women with high income and educational level.
The low socio-economic group (group L, N =101) consisted of rural, low income, illiterate women. Both
groups contained three subgroups (non-pregnant, non-lactating =1, pregnant=2, lactating =3). Socioeconomic status had a significant effect on body weight, height, biceps and triceps skinfolds, BMI, TBF, FFM
and BF% (P<0.001). These variables were significantly higher (P< 0.001) in all subgroups of group H than in
the corresponding subgroups of group L. The influence of physiological status on most of these variables was
not significant. EI was, however, influenced by both socio-economic (P<0.001) and physiological
(P<0.05) status. The mean EI was significantly lower (P<0.001) in all subgroups of group L than in the
corresponding subgroups of group H. The contributory sources were different in high and low income groups.
In both groups, EI was lower than the recommended level. Based on the dietary and anthropometric results, we
conclude that malnutrition is a common feature among low income rural women. This contradicts findings in
western countries, where obesity is prevalent in low income groups.
Asia Pac J Clin Nutr. 2004;13(1):61-68.doi:
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Do Thai women of child bearing age need preconceptional supplementation of dietary folate?
Author:Chutima Sirikulchayanonta MD, Kannatcha Madjupa MS
Keywords:serum folate, dietary folate intake, child-bearing age women, preconceptual, Thailand
Abstract:Recent studies in western countries have indicated that women with low serum folate before pregnancy have
greater risk of giving birth to babies with neural tube defects, and preconceptional folate supplementation has
been recommended to prevent such defects. To determine whether Thai women needed folate supplementation
before pregnancy, we carried out a cross-sectional study from September 2001 to January 2002. The objectives
were to determine serum folate levels among women of child-bearing age and their relationship to dietary
folate intake. One hundred and sixty-five apparently healthy, volunteer women aged 15 – 45 years were
recruited from the Family Planning Clinic, Mother and Child Hospital, Health Promotion Centre, Region I,
Bangkok. Data on general characteristics, nutritional status and dietary folate intake were recorded while
venous blood was drawn for serum folate analysis. Results showed that 65.5% of the study group had low
dietary folate intake, that 18% had low serum folate, and that there was a significant correlation between
dietary intake and serum level (r= 0.68, P<0.001). There were also significant correlations between serum
level and body mass index, (r= 0.13, P<0.001). However, there were no significant associations between
serum level and age, educational level, occupation, family income, or duration vegetables were stored in the
refrigerator before consumption. In conclusion, there is preliminary evidence that some pregnant Thai women
may have sufficiently low serum folate levels to put their babies at risk. We recommend further study on a
larger scale to confirm whether folate supplementation is needed for Thai women at child bearing age. In the
interim, it may be wise for obstetricians to measure serum folate in pregnant women to determine whether
folate supplementation is required.
Asia Pac J Clin Nutr. 2004;13(1):69-73.doi:
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The hypertriglyceridaemic waist in New Zealand Maori
Author:Damon Bell MBCHB, Kirsten A McAuleyMBCHB, PhD, Jim
Keywords:insulin resistance, fasting insulin, triglycerides, waist circumference, abdominal obesity, Maori, New Zealand
Abstract:The objective of this study was to find a simple practical method of predicting insulin resistance in New
Zealand Maori. Thirty-six Maori participants had insulin sensitivity measured using a euglycaemic insulin
clamp. Several clinical and easily measured laboratory variables were compared, singly and in combination,
with this measure of insulin sensitivity usually regarded as the gold standard. The combination of either fasting
insulin and triglycerides or waist circumference and triglycerides, were the best simple methods for predicting
insulin resistance in Maori. As insulin assays are not always available and are often not standardised,
measurement of waist circumference and triglycerides provides a practical method for predicting insulin
sensitivity in New Zealand Maori.
Asia Pac J Clin Nutr. 2004;13(1):74-77.doi:
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Interaction among body composition, self-rated health and functional status of the elderly in an Indian population
Author:Kanala Kodanda Rami Reddy PhD, FICN,Battena Krishn
Keywords:elderly, anthropometry, self-rated health, activities of daily living, well-being, Andhra Pradesh, Tirupati, India
Abstract:The present study examined the relationship among body composition, measures of self-rated health and
activities of daily living in a group of free living poor elderly aged ≥60 years with a sample size of 147 subjects
(82 males, 65 females) from Tirupati suburbs of Andhra Pradesh, India. The subjects were divided into three
age groups i.e. 60-69, 70-79 and ≥80 years for comparison. Mean height, weight, circumferences of waist and
hip and waist hip ratio (WHR) were higher in males than females with no difference in body mass index
(BMI). However, none of the anthropometric variables showed significant association with age. The majority
of the subjects rated themselves as ‘poor’ or ‘fair’ self-rated health and this corresponds well with the lower
mean values of anthropometry as well as activities of daily living, well-being and memory and cognitive
function, impaired health aids and in general health. Polytomous logistic regression showed that subjects with
the highest score on well-being compared to the lowest score rated 0.325 times (CI: 0.124, 0.851; P<0.05)
good vs fair. The odds ratio was 0.519 times (CI: 0.206, 1.306) between good vs poor. Regarding BMI,
subjects who rated their health as good/fair tended to have BMI in the normal range. In the poor self-rated
health group a maximum of 55% of males and 47% of females were below 19 units of BMI, which was
reflected in the increase in odds ratio of 1.361in males and 1.134 in females between good vs poor health
ratings. The findings reveal that well-being and BMI are related to self-reported health status.
Asia Pac J Clin Nutr. 2004;13(1):78-85.doi:
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The impact of usual dietary patterns, selection of significant foods and cuisine choices on changing dietary fat under ‘free living’ conditions
Author:Linda C Tapsell PhD, APD, Anita Hokman MSc, APD, A
Keywords:dietary change, dietary fat, food habits, cuisine, Australia
Abstract:Dietary guidelines for the general population and for the management of obesity, diabetes and heart disease
suggest a reduction in dietary fat, and in particular dietary saturated fatty acids (SFA). In order to achieve the
recommended levels, changes in food choice patterns are required. Foods are consumed in combination with
other foods, and these combinations are often recognizable as cuisine patterns. In this study we examined the
food choice patterns of a group of 63 adults with existing type 2 diabetes mellitus who completed a 12 month
dietary intervention trial aimed at changing dietary fat under ‘free living’ conditions. In both lower fat (LF,
27%E) and modified fat (MF, 37%E) groups, a reduction in dietary SFA and an increase in polyunsaturated fat
were required, with an additional requirement to increase dietary monounsaturated fat in the MF group. The
usual diets of the study sample were on average low in total fat (27%E), but high in saturated fat (12%E).
Those already consuming total fat at the level concordant with their allocation (LF or MF) achieved targets
faster than those with a discordant allocation, but there was no significant effect of usual diet on time of target
achievement at 12 months. At 6 months, those achieving dietary fat targets had changed to low fat dairy
products and leaner meats, were having more spreads, oils, and nuts and were consuming takeaway meals less
than twice a week. Contributions to dietary fat shifted from takeaway foods, meat, dairy products and cakes to
spreads, oils and nuts. The modified fat and low fat groups chose more Mediterranean and South East Asian
cuisines respectively. In this study sample, usual dietary patterns had an initial impact on change in the diet, but
identifiable changes in food choice patterns and the adoption of certain cuisines that combined foods indicative
of the dietary guidelines resulted in successful achievement of dietary fat targets.
Asia Pac J Clin Nutr. 2004;13(1):86-91.doi:
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Effects of convenience rice congee supplemented diets on guinea pig whole animal and gut growth, caecal digesta SCFA and in vitroileal contractility
Author:Glen S Patten BSc Hons, Anthony R Bird PhD, David
Keywords:ileum, contractility, guinea pig, fibre, eicosanoid, short chain fatty acids, SCFA
Abstract:The aim of the study was to feed convenience baby food brown rice (BC) and white rice (WC) congee diets
compared to egg custard (EC) and baked bean (BB) diets to newborn guinea pig pups. Diets were isocaloric
and formulated to contain equal macronutrient content of carbohydrate, protein, fat and fibre. Diets were
supplemented with essential nutrients, fruit and vegetables and decrementally with standard chow for
palatability. We investigated the acceptability of the diets and specifically whether the different natural fibre
content of these diets could influence whole animal and small intestinal growth, caecal digesta properties and
specifically in vitroileal contractility. After 8 weeks of feeding, the mean body weight of WC group was
significantly lower than the BB group. WC group had lower small intestine weight than both BC group and BB
group resulting in lower small intestine density compared to BB group. Caecal digesta pH and total short chain
fatty acid (SCFA) concentration were similar. However, butyrate was higher in the BB group compared to the
other diets. Contractility studies revealed a small but significantly higher voltage was required to initiate ileal
contraction of BC group compared to both the EC and BB groups. All dietary groups responded similarly to
acetylcholine, histamine, serotonin, PGE2, PGF
2α, and 8-iso-PGE2
. There were no differences on inhibition of
electrically-driven contraction by morphine or epinephrine. The newborn guinea pig model was an effective
system for testing, with limitations, supplemented convenience baby foods with variable natural fibre content
that demonstrated significant effects on animal growth, caecal digesta SCFA and intestinal contractility.
Asia Pac J Clin Nutr. 2004;13(1):92-100.doi:
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Inhibitory effects of rosmarinic acid extracts on porcine pancreatic amylase in vitro
Author:Patrick P McCue MS and Kalidas Shetty PhD
Keywords:amylase inhibitors, oregano, lemon balm, herbal extracts, rosmarinic acid, diabetes me llitus
Abstract:Porcine pancreatic alpha-amylase (PPA) was allowed to react with herbal extracts containing rosmarinic acid
(RA) and purified RA. The derivatized enzyme -phytochemic al mixtures obtained were characterized for
residual amylase activity. These in vitro experiments showed that the amylase activity was inhibited in the
presence of these phytochemicals. The extent of amylase inhibition correlated with increased concentrati on of
RA. RA -containing oregano extracts yielded higher than expected amylase inhibition than similar amount of
purified RA, suggesting that other phenolic compounds or phenolic synergies may contribute to additional
amylase inhibitory activity. The significance of food -grade, plant-based amylase inhibitors for modulation of
diabetes mellitus and other oxidation-linked diseases is hypothesized and discussed.
Asia Pac J Clin Nutr. 2004;13(1):101-106.doi:
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Nutritional indicators, peripheral blood lymphocyte subsets and survival in an institutionalised elderly population
Author:Widjaja Lukito PhD, Naiyana Wattanapenpaiboon PhD
Keywords:lymphocytes, T-cells, B -cells, natural killer cells, iron status, zinc status, survival, total mortality
Abstract:The objectives of this study were to determine the percentage and absolute counts of the peripheral blood
lymphocyte subsets, and to examine the relationship between lymphocyte subsets and nutritional status, and total
mortality in an institutionalised elderly population. Design The study had a c ross- sectional and observational
design. The sample of 115 permanent elderly residents was drawn from large geriatric institution in Melbourne,
Australia. The main outcome measures were as follows : (i) percentages and absolute counts of lymphocyte
subsets, (ii) association between biochemical indices of nutritional status (ferritin, iron and zinc) and peripheral
bloodlymphocyte subsets, (iii) total mortality during a 22 -month period in relation to baseline lymphocyte
subset counts. Women had higher absolute counts of various lymphocyte subsets than men. Positive correlations
of serum ferritin with the number of CD8 (T -suppressor cell) and of serum iron with CD56 (natural killer, NK
cells) were observed in men. In women, serum zinc was positively correlated with the absolute counts of CD3
(total T -cells), CD4 (T -helper cell) and CD19 (total B-cell). The analysis of survival data after 22 months
showed that the mean number of CD4 cells of non-survivors (524 ±292 x10
6
cells/L) was significantly lower
than that of survivors (759 ±292 x10
6
cells/L). The biochemical indicators of iron and zinc status partly account
for variations in lymphocyte subset counts, consistent with known effects of iron overload and of zinc deficiency
on immunocompetence. The number of CD4 T -cells may be useful in the prediction of total mortality in an
institutionalised elderly population.
Asia Pac J Clin Nutr. 2004;13(1):107-112.doi:
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