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

Abstract

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.

Figure 1

Flow diagram for the population and the protocol activities during the intervention study.

Figure 2

Repeat measurements of intestinal barrier function parameter in the same child by time and groups during four months follow-up in children participating in the intervention study at urban community Parque Universitário, Fortaleza, CE, Brazil, June, 2000 to October, 2007.

Figure 3

Incidence of total intestinal parasitic and Giardia spp. at enrollment and one month follow-up in children participating in the vitamin A treatment study at urban community Parque Universitário, Fortaleza, CE, Brazil, June, 2000 to October, 2007. Stool samples were available for parasitic examination on 85% (63/74; 33 in the placebo and 30 in the vitamin A group) at enrollment and 79% (56/71; 31 in placebo and 25 in the vitamin A group).