Background
This study evaluates the effects of retinol on intestinal barrier function, growth, total parasites and Giardia spp. infections in children in the Northeast of Brazil.
Methods
The study was a double-blind, randomized placebo-controlled trial (http://clinicaltrials.gov;Register#NCT00133406) involving 79children reiceved vitamin A 100,000 - 200,000 IU (n = 39) or placebo (n = 40) at enrollment, 4 and 8 months, followed for 36 months. Intestinal barrier function was evaluated using the lactulose:mannitol 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 one month did not change between groups (p>0.05). Total intestinal parasitic specifically new infections were significantly lower in the vitamin A treatment compared to 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 (WHZ), length or height-for-age z-scores (HAZ), and weight-for-age (WAZ) 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 to the placebo group, suggesting that vitamin A improves host defenses against Giardia infections.