Search

Background: Nutritional status is highly dependent on season in countries such as The Gambia. In a rural Gambian setting, individuals born during periods of seasonal nutritional deprivation ("hungry seasons") are susceptible to mortality from infectious diseases in adult life., Objective: We investigated the hypothesis that impaired immunocompetence in those born in the hungry season results from an underlying defect in immunologic memory, similar to the immunosenescence of old age, which is likely to be reflected in the phenotype and kinetics of T lymphocytes in young adults., Design: T cell phenotype in terms of CD3, CD4, CD8, CD45RA, and CD45R0 expression and in vivo dynamics measured by stable isotope labeling of T cell subsets combined with gas chromatography-mass spectrometry and frequency of T cell receptor excision circles were measured in 25 young (18-24-y-old) Gambian men. Thirteen of these 25 men were exposed to perinatal malnutrition as defined by birth season and birth weight., Results: In persons born in the hungry season with low birth weight, no differences in the proportions of memory or naive T cells were found. Kinetic analysis showed higher proliferation rates in memory (CD45R0(+)) subsets of T cells than in naïve (CD45R0(-)) cells, which is consistent with previous studies, but no evidence was found for an effect of birth weight or season on T lymphocyte proliferation and disappearance rates. No significant correlations were found between in vivo T cell kinetics and frequency of T cell receptor excision circles. Only absolute numbers of granulocytes were elevated in those born in the nutritionally deprived season., Conclusion: In healthy young Gambian men, T lymphocyte homeostasis is extremely robust regardless of perinatal nutritional compromise.

Background: The vitamin A requirements of elderly humans have not been studied., Objective: In a cross-sectional study of 60-88-y-old men (n = 31) and women (n = 31) in rural Philippines, we assessed the dietary intakes of elders with adequate (> or = 0.07 micromol/g) or low (< 0.07 micromol/g) liver vitamin A concentrations to estimate vitamin A requirements for this age group., Design: Total-body vitamin A was assessed by the deuterated-retinol-dilution technique; liver vitamin A concentrations were assessed by assuming that liver weight is 2.4% of body weight and that, in this marginally nourished population, 70% of total-body vitamin A is in the liver; serum retinol was measured by HPLC; and dietary intakes were assessed with 3 nonconsecutive 24-h dietary recalls. The mean vitamin A intake + 2 SDs of subjects with adequate liver vitamin A concentrations was used to estimate an acceptable or sufficient vitamin A intake value for elders., Results: The mean (+/- SD) vitamin A intakes of the men and women with adequate vitamin A in liver were 135 +/- 86 and 134 +/- 104 microg retinol activity equivalents (RAE)/d, respectively; intakes of the men and women with low vitamin A in liver were 75 +/- 53 and 60 +/- 27 microg RAE/d, respectively. Total-body vitamin A or liver vitamin A but not serum retinol correlated with dietary RAE, preformed vitamin A, beta-carotene, fat, and protein. An estimated acceptable or sufficient dietary vitamin A intake associated with adequate liver vitamin A concentrations in elders is 6.45 microg RAE/kg body wt; for a reference 76-kg man and a 61-kg woman, these values are approximately 500 and 400 microg RAE/d, respectively., Conclusion: The dietary vitamin A intakes of elders with adequate or low liver vitamin A concentrations as estimated by use of the deuterated-retinol-dilution technique are useful for assessing vitamin A requirements.

Background: It is important to understand the factors affecting strategies to improve the vitamin A status of populations. We reported previously that a 3-d deuterated-retinol-dilution (DRD) procedure might be used to indicate total body stores of vitamin A., Objective: We studied the ability of 3-d DRD to detect changes in the body pool size of vitamin A and the effect of vitamin A status on the bioconversion of plant carotenoids to vitamin A., Design: Two separate, unrelated studies were conducted in 7-13-y-old children with poor or marginal serum retinol concentrations (0.32-0.93 micromol/L) by feeding them controlled diets daily for 5 d/wk for 12 wk, after treatment with an anthelmintic drug. In school 1 (n = 27), lunch and 2 snacks that were provided at school contained 2258 retinol equivalents/d (mostly from orange fruit and vegetables) and 5.3 MJ/d from 33 g fat, 37 g protein, and 209 g carbohydrates; in school 2 (n = 25), 2 snacks provided 2.5 MJ/d from 9.4 g fat, 9.6 g protein, and 119 g carbohydrates, but no carotenes., Results: In school 1, mean serum beta-carotene increased from 0.12 to 0.62 micromol/L (P = 0.0001) and serum retinol increased from 0.68 to 1. 06 micromol/L (P = 0.0001). In school 2, serum beta-carotene increased from 0.06 to 0.11 micromol/L (P = 0.0001) and serum retinol increased from 0.66 to 0.86 micromol/L (P = 0.0001). In school 1, but not school 2, improvement in serum retinol varied inversely with baseline retinol (r = -0.38, P = 0.048). In both schools, 3-d DRD showed reductions in the ratio of serum deuterated to nondeuterated retinol (D:H retinol) postintervention, denoting improvements in vitamin A status; the higher D:H retinol (ie, the poorer the status) at baseline, the greater the reduction in D:H retinol postintervention (school 1: r = -0.99, P = 0.0001; school 2: r = -0.89, P = 0.0001)., Conclusions: Three-day DRD can detect changes in the body pool size of vitamin A, although a predictive equation to quantitate total body stores of vitamin A with the use of 3-d data needs to be developed. Bioconversion of plant carotenoids to vitamin A varies inversely with vitamin A status; improvement in status after dietary interventions is strongly influenced by total body stores of vitamin A and is influenced little or not at all by serum retinol.