Effects of Vitamin A Supplementation on Intestinal Barrier Function, Growth, Total Parasitic, and Specific Giardia spp Infections in Brazilian Children: A Prospective Randomized, Double-blind, Placebo-controlled Trial

Background: This study evaluates the effects of retinol on intestinal barrier function, growth, total parasites, and Giardia spp infections in children in northeastern Brazil. Subjects and Methods: The study was a double-blind, randomized placebo-controlled trial (http://clinicaltrials.gov; register no. # NCT00133406) involving 79 children who received vitamin A 100,000-200,000 IU (n = 39) or placebo (n = 40) at enrollment, 4, and 8 months and were followed for 36 months. Intestinal barrier function was evaluated using the lactulose: mannitol ratio test. Stool lactoferrin was used as a marker for intestinal inflammation. Results: The groups were similar with regard to age, sex, nutritional parameters (z scores), serum retinol concentrations, proportion of lactoferrin-positive stool samples, and intestinal barrier function. The lactulose: mannitol ratio did not change during the same time of follow-up (P> 0.05). The proportion of lactoferrin-positive samples evaluated at 1 month did not change between groups (P> 0.05). Total intestinal parasitic, specifically new, infections were significantly lower in the vitamin A treatment compared with control group; these were accounted for entirely by significantly fewer new Giardia infections in the vitamin A treatment group. The cumulative z scores for weight-for-length or height, length or height-for-age z scores, and weight-for-age did not change significantly with vitamin A intervention for 36 months of follow-up. Conclusions: These data showed that total parasitic infection and Giardia spp infections were significantly lower in the vitamin A treatment group when compared with the placebo group, suggesting that vitamin A improves the host's defenses against Giardia infections.