Fig. 1

Participant flow diagram. All participants completed a 2-week baseline period. Participants were then randomly allocated to receive the probiotic or placebo supplement and were later allocated to receive the alternative supplement in this crossover study design. The intervention periods (3 weeks each) were separated by a 4-week washout period (2-weeks of washout followed by 2 weeks of a baseline period before the second intervention). The study concluded with a final 2-week washout period. Participants were recruited and completed the study between 2018 and 2019