Effects of acute bovine colostrum supplementation on immune responses to prolonged cycling: a randomised crossover trial

PURPOSE: The purpose of this double-blind placebo-controlled crossover trial was to assess the effects of acute bovine colostrum supplementation on exercise-induced changes in neutrophil function and mucosal immunity following prolonged exercise. METHODS: Sixteen healthy, recreationally active males participated in two trials in a randomised counterbalanced order. Participants either consumed doses of bovine colostrum or an isoenergetic placebo 1 h (30 g) and immediately prior (5 g) to 2.5 h of cycling at 15% Δ with a further dose midway through the exercise (5 g). Venous blood and unstimulated saliva samples were obtained at baseline, 1 h post-consumption (pre-exercise), immediately post-exercise and 1 h post-exercise. A mechanistic sub-study was performed to determine whether plasma obtained from participants following bovine colostrum consumption directly enhances neutrophil function. RESULTS: Compared to placebo, a greater fMLP-stimulated blood neutrophil oxidative burst was observed (~ 15% difference across timepoints) with bovine colostrum (trial, p < 0.05). In the sub-study, fMLP-stimulated neutrophil oxidative burst was enhanced when whole blood was pre-incubated with plasma obtained 1 h following colostrum consumption. There was greater salivary lysozyme concentration and bacterial-stimulated blood neutrophil elastase release at post-exercise and 1 h post-exercise respectively in the bovine colostrum trial (trial × time interaction, p < 0.05). There was no effect of bovine colostrum on leukocyte trafficking, PMA-stimulated neutrophil oxidative burst, salivary secretory immunoglobulin A and salivary lactoferrin. CONCLUSION: Acute bovine colostrum supplementation can modify innate immune responses to prolonged exercise, which may be due to components or metabolites of bovine colostrum that become bioavailable following consumption.