The impact of vitamin A supplementation on physical growth of children is dependent on season

Abstract

Objective: To determine the impact of vitamin A supplementation on physical growth in young children.

Design: Randomized, double blind, placebo controlled trial.

Setting: Urban slum community clinic.

Subjects: 900 children, aged 12-59 months, attending the community clinic with diarrhea of < or = 7 d were included in the trial.

Intervention: Each child was given a single dose capsule containing 200,000 IU vitamin A or placebo at enrollment.

Main outcome measures: Mean increments in weight and height during the 90 d period post supplementation.

Results: In all children, the mean increments in weight following supplementation were 0.66 kg (s.d. 0.5) and 0.64 kg (s.d. 0.6) in the vitamin A and placebo groups (P = 0.5). The mean increments in height were also similar in the two treatment groups (P = 0.5). Serum vitamin A was measured in 40 randomly selected children in each group; the proportion of subclinical deficiency (serum retinol < 20 micrograms/dl) was 62.5% in those enrolled during summer (April through July) as compared to 21.1% in those enrolled during the remaining cooler months of the year (P = 0.02). In the children supplemented with vitamin A during summer, the mean increment in weight was 140 g more than those who received placebo (95% confidence interval CI 30-250); there was also a significant reduction in the proportion of children who were wasted (< -2 weight-for-height Z-score) at end study (Odds Ratio 0.53, 95% CI 0.28-1.0, P = 0.03). There was no significant impact of vitamin A on height increments in children supplemented during summer.

Conclusion: Vitamin A supplementation in 12-59 month old children improves weight gain in the subsequent three months only in the summer season, but not during the rest of the year.