Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes

Randomized placebo-controlled interventional trial in healthy male professional mixed martial arts fighters undergoing intensive in-season training. Eight participants were randomized to the colostrum arm in a 1:1 allocation design.

The active regimen was oral freeze-dried whole bovine colostrum powder, 500 mg per dose twice daily for 20 days. Each dose was taken 30 minutes before a meal. Participants in the active arm were randomized against placebo in a blinded phase, with an open-label crossover phase afterward.

Bovine colostrum improved intestinal permeability and lowered stool zonulin compared with placebo, with the overall effect judged beneficial. Colostrum supplementation significantly decreased intestinal permeability (p = 0.01), and the post-intervention change in zonulin differed from placebo (p = 0.03). In the open-label crossover phase, differential sugar absorption also differed (p = 0.02), with zonulin changes remaining significant at day 44 versus day 22 (p = 0.0008) and day 44 versus day 0 (p = 0.006). The intervention was generally well tolerated, with no important treatment-associated digestive side effects reported in the colostrum group.

Very small active-arm sample size and short 20-day intervention limit precision and generalizability. Participants were all healthy male elite athletes, so findings may not extend to women, non-athletes, or patients with gastrointestinal disease. The open-label crossover phase and limited reporting of arm-specific baseline characteristics further constrain interpretation.