Functional abdominal bloating is one of the functional gastrointestinal disorders (FGIDs). Here, we aimed to investigate and compare the effects of probiotics and bismuth subsalicylate on abdominal bloating.

This is a double-blinded randomized clinical trial performed on 125 patients with functional abdominal bloating in Isfahan in 2020-2021. At the beginning of the study, information on the frequency of abdominal bloating, its severity, the occurrence of early satiety, frequency of borborygmus, frequency of belching, and the frequency of defecation per week was collected. Patients were divided into 3 groups receiving Familact Probiotic Pills that contained 9 bacterial strains every 12 hours, bismuth subsalicylate tablets, 120 mg every 12 hours, and placebo pills for 4 weeks. Afterward, the frequency and severity of abdominal bloating and other symptoms were evaluated and compared.

After 2 weeks, patients in the probiotic group had a significantly lower frequency of abdominal bloating compared to other groups (p= 0.006). After 4 and 8 weeks, patients in the probiotic group and bismuth group had a lower frequency of bloating compared to placebo (P= 0.001 and P= 0.037, respectively). During the study, patients in the probiotic and bismuth groups had a significantly lower bloating severity compared to placebo (P< 0.05). The frequency of borborygmus was significantly lower in the probiotic group after 2 and 4 weeks during the study compared to other groups (P= 0.010 and P= 0.013, respectively), but there were no significant differences between placebo and bismuth groups (P> 0.05).

According to our data, consumption of probiotics improves the frequency and severity of abdominal bloating and reduces borborygmus. Bismuth subsalicylate also has significant effects.