Data will be reported as s mean±SD if normally distributed and as median(25-75% percentiles) if not. The Shapiro-Wilk test is performed to assess whether data are normally distributed. Statistical comparisons of normally distributed data are performed using Student's t-test. Mann-Whitney U-test is used to compare the rank variables measuring gastrointestinal symptoms in probiotics and placebo groups. The threshold for statistical significance is at p values <0.05. And an external statistical consultant from our Clinical Research Center will be involved in the data validation and analysis activities.