Effects of bovine whey protein on exercise-induced gut permeability in healthy adults: a randomised controlled trial

Purpose Intestinal permeability is a critical component of gut barrier function. Barrier dysfunction can be triggered by certain stressors such as exercise, and if left unmanaged can lead to local and systemic disorders. The aim of this study was to investigate the effects of a specific whey protein fraction in alleviating exercise-induced gut permeability as assessed by recovery of lactulose/rhamnose (L/R) and lactulose/mannitol (L/M) urinary probes. Methods Eight males and eight females (aged 18-50) completed two arms of a double-blind, placebo-controlled, crossover study. For each arm participants performed two baseline intestinal permeability assessments, following which they consumed the treatment (2 g/day of milk powder containing 200 mg of whey protein) or placebo (2 g/day of milk powder) for 14 days, before performing a post-exercise permeability assessment. The exercise protocol involved a 20-min run at 80% of maximal oxygen uptake on a 1% incline. Results Mixed model analysis revealed an increase in L/R (23%; P < 0.001) and L/M (20%; P < 0.01) recovery following exercise. However, there was no treatment or treatment x exercise effect. Conclusion The exercise protocol utilised in our study induces gut permeability. However, consuming whey protein, at the dose and timing prescribed, is not able to mitigate this effect.