Association between serum vitamin D, retinol and zinc status, and acute respiratory infections in underweight and normal-weight children aged 6-24 months living in an urban slum in Bangladesh.

We conducted a longitudinal assessment in 466 underweight and 446 normal-weight children aged 6-24 months living in the urban slum of Dhaka, Bangladesh to determine the association between vitamin D and other micronutrient status with upper respiratory tract infection (URI) and acute lower respiratory infection (ALRI). Incidence rate ratios of URI and ALRI were estimated using multivariable generalized estimating equations. Our results indicate that underweight children with insufficient and deficient vitamin D status were associated with 20% and 23-25% reduced risk of URI, respectively, compared to children with sufficient status. Underweight children, those with serum retinol deficiency were at 1·8 [95% confidence interval (CI) 1·4-2·4] times higher risk of ALRI than those with retinol sufficiency. In normal-weight children there were no significant differences between different vitamin D status and the incidence of URI and ALRI. However, normal-weight children with zinc insufficiency and those that were serum retinol deficient had 1·2 (95% CI 1·0-1·5) times higher risk of URI and 1·9 (95% CI 1·4-2·6) times higher risk of ALRI, respectively. Thus, our results should encourage efforts to increase the intake of retinol-enriched food or supplementation in this population. However, the mechanisms through which vitamin D exerts beneficial effects on the incidence of childhood respiratory tract infection still needs further research.

Association of vitamin D status with incidence of enterotoxigenic, enteropathogenic and enteroaggregative Escherichia coli diarrhoea in children of urban Bangladesh.

OBJECTIVE: To evaluate the association between vitamin D status and diarrhoeal episodes by enterotoxigenic (ETEC), enteropathogenic (EPEC) and enteroaggregative (EAEC) E. coli in underweight and normal-weight children aged 6-24 months in urban Bangladesh. METHODS: Cohorts of 446 normal-weight and 466 underweight children were tested separately for ETEC, EPEC and EAEC from diarrhoeal stool samples collected during 5 months of follow-up while considering vitamin D status at enrolment as the exposure. Cox proportional hazards models with unordered failure events of the same type were used to determine diarrhoeal risk factors after adjusting for sociodemographic and concurrent micronutrient status. RESULTS: Vitamin D status was not independently associated with the risk of incidence of ETEC, EPEC and EAEC diarrhoea in underweight children, but moderate-to-severe retinol deficiency was associated with reduced risk for EPEC diarrhoea upon adjustment. Among normal-weight children, insufficient vitamin D status and moderate-to-severe retinol deficiency were independently associated with 44% and 38% reduced risk of incidence of EAEC diarrhoea, respectively. These children were at higher risk of ETEC diarrhoea with vitamin D deficiency status when adjusted for micronutrient status only. CONCLUSION: This study demonstrates for the first time that normal-weight children with insufficient vitamin D status have a reduced risk of EAEC diarrhoea than children with sufficient status. Moderate-to-severe deficiency of serum retinol is associated with reduced risk of EPEC and EAEC diarrhoea in underweight and normal-weight children.

Vitamin-D status is not a confounder of the relationship between zinc and diarrhoea: a study in 6-24-month-old underweight and normal-weight children of urban Bangladesh.

BACKGROUND/OBJECTIVE: The role of micronutrients particularly zinc in childhood diarrhoea is well established. Immunomodulatory functions of vitamin-D in diarrhoea and its role in the effect of other micronutrients are not well understood. This study aimed to investigate whether vitamin-D directly associated or confounded the association between other micronutrient status and diarrhoeal incidence and severity in 6-24-month underweight and normal-weight children in urban Bangladesh. SUBJECTS/METHODS: Multivariable generalised estimating equations were used to estimate incidence rate ratios for incidence (Poisson) and severity (binomial) of diarrhoea on cohorts of 446 normal-weight and 466 underweight children. Outcomes of interest included incidence and severity of diarrhoea, measured daily during a follow-up period of 5 months. The exposure of interest was vitamin-D status at enrolment. RESULTS: Normal-weight and underweight children contributed 62 117 and 62 967 day observation, with 14.2 and 12.8 days/child/year of diarrhoea, respectively. None of the models showed significant associations of vitamin-D status with diarrhoeal morbidity. In the final model, zinc-insufficient normal-weight children had 1.3 times more days of diarrhoea than sufficient children (P<0.05). Again zinc insufficiency and mother's education (1-5 and >5 years) had 1.8 and 2.3 times more risk of severe diarrhoea. In underweight children, older age and female had 24-63 and 17% fewer days of diarrhoea and 52-54 and 31% fewer chances of severe diarrhoea. CONCLUSION: Vitamin-D status was not associated with incidence and severity of diarrhoea in study children. Role of zinc in diarrhoea was only evident in normal-weight children. Our findings demonstrate that vitamin-D is not a confounder of the relationship between zinc and diarrhoea.

Randomised comparison of the effects of Sprinkles and Foodlets with the currently recommended supplement (Drops) on micronutrient status and growth in Iranian children.

BACKGROUND/OBJECTIVES: Multiple micronutrient supplementation with Sprinkles powder and crushable Foodlets tablets may be effective means of controlling micronutrient deficiencies in infants. Their efficacy has not been tested in countries like Iran where wheat as the staple food may affect nutrient bioavailability. This study aimed to compare the efficacy of Sprinkles, Foodlets and the current supplement (Drops) for improving micronutrient status and growth among Iranian infants. SUBJECTS/METHODS: Infants of 6-18 months of age, living in an urban district of Iran were randomised to receive daily Sprinkles (n=120), Foodlets (n=121) or Drops (n=121) for 4 months. Haemoglobin (Hb), serum ferritin, serum retinol, serum zinc, 25(OH) D concentration and anthropometry were assessed at baseline and at 4 months. RESULTS: Iron status improved with all treatments. Drops showed significantly greater changes in Hb and serum ferritin, though changes in anaemia prevalence were not different across groups. Infants having Foodlets and Sprinkles had significantly greater reductions in proportion of children with zinc deficiency compared with Drops. No significant differences in treatment effects were observed for mean serum 25(OH) D and retinol, or for growth of infants across groups. CONCLUSION: The study was the first efficacy trial with Sprinkles and Foodlets in the Middle East where wheat or rice is the principal complementary foods. Differences across treatment groups were largely consistent with supplement micronutrient composition for iron and zinc, with no benefit in this population for serum retinol, 25(OH) D, growth or anthropometric status. The trial identified trade-offs in combining multiple micronutrients in a single delivery mechanism.

Interaction of zinc or vitamin A supplementation and specific parasite infections on Mexican infants' growth: a randomized clinical trial.

BACKGROUND: The efficacy of micronutrient supplementation on growth may be modified by specific gastrointestinal parasite infections. METHODS: We carried out a double-blind placebo-controlled trial to evaluate the effect of vitamin A and zinc supplementation on gastro-intestinal pathogen infections and growth among 584 infants in Mexico City. Children aged 5-15 months were assigned to receive either a vitamin A supplement every 2 months (20,000 IU of retinol for infants < or =; 1 year or 45,000 IU for infants >1 year), a daily supplement of 20 mg of zinc, a combined vitamin A-zinc supplement or a placebo, and were followed up for 1 year. Weight and length were measured once a month and morbidity histories were recorded twice a week for 12 months. Monthly stool samples were screened for Giardia duodenalis, Ascaris lumbricoides and Entamoeba spp. Growth velocity slopes, generated from the linear regression of individual child length, and height-for-age z-scores on time were analyzed as end points in regression models, adjusting for the presence of parasite infections. RESULTS: The main effect of vitamin A supplementation was in height improvement (P<0.05), and was only found in the model evaluating infants with any parasite. There was an interaction effect of slower growth (P<0.05) found in infants infected with any parasite and supplemented with vitamin A in slower growth (P<0.05). In addition, the interaction of zinc supplementation and Giardia duodenalis or A. lumbricoides was associated with reduced growth (P<0.05). CONCLUSION: Gastro-intestinal parasite infections may modify the effect that zinc or vitamin A supplementation has on childhood growth.

Proportional hazards analysis of diarrhea due to enterotoxigenic Escherichia coli and breast feeding in a cohort of urban Mexican children.

Ninety-eight women-infant pairs were followed for up to 50 weeks in the northern part of Guadalajara, Mexico, from August 1986 to July 1987 as part of a community-based, prospective study of the relation between infant feeding patterns and enterotoxigenic Escherichia coli producing heat-labile toxin (LT-ETEC) diarrheal disease. Strictly formula-fed children had an incidence of diarrhea over three times that of strictly breast-fed infants and twice that of breast-fed and supplementally fed children. Strictly formula-fed infants colonized by LT-ETEC were symptomatic for diarrhea nearly three times as often as strictly breast-fed infants and twice as often as infants receiving a mixed diet. The fitting of parametric hazard models to durations until LT-ETEC colonization revealed that the hazard for the first colonization was time invariant. The hazard of diarrhea increased by 400-500% during the rainy season or among children 3 months of age or older who received avena, a barley drink. The best-fitting hazard models to durations until symptomatic expression of LT-ETEC infection all increased through time. This hazard was inversely impacted by the overall amount of LT-ETEC-specific, immunoglobulin A antibodies the infant received via the mother's breast milk and by the provision of traditional medicinal teas.