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

J Pediatr Gastroenterol Nutr. 2010 Mar;50(3):309-15. doi: 10.1097/MPG.0b013e3181a96489.


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.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / pharmacology
  • Adjuvants, Immunologic / therapeutic use*
  • Biomarkers
  • Child
  • Child, Preschool
  • Dietary Supplements*
  • Double-Blind Method
  • Feces
  • Female
  • Giardiasis / parasitology
  • Giardiasis / prevention & control*
  • Growth / drug effects*
  • Humans
  • Inflammation / metabolism
  • Intestinal Mucosa / drug effects*
  • Intestinal Mucosa / parasitology
  • Intestinal Mucosa / physiopathology
  • Lactoferrin / metabolism
  • Male
  • Protozoan Infections / parasitology
  • Protozoan Infections / prevention & control
  • Vitamin A / pharmacology
  • Vitamin A / therapeutic use*
  • Vitamins / pharmacology
  • Vitamins / therapeutic use*


  • Adjuvants, Immunologic
  • Biomarkers
  • Vitamins
  • Vitamin A
  • Lactoferrin

Associated data

  • ClinicalTrials.gov/NCT00133406