Effects of a Bacillus subtilis HU58 and Heyndrickxia faecalis SC208 spore-forming probiotic formula on gastrointestinal health: results of a randomised, double-blind, placebo-controlled pilot study

Irritable bowel syndrome (IBS) is a chronic functional disorder characterised by abdominal pain and altered bowel habits. The most prevalent subtype is diarrhoea-predominant IBS (IBS-D). The combination of Bacillus subtilis HU58 and Heyndrickxia faecalis (formerly Bacillus coagulans) SC208 has previously exerted positive effects in people with antibiotic-associated diarrhoea and infective diarrhoea. The present multicentre study conducted in India aimed to evaluate the effectiveness and safety of the dual-strain probiotic in adults (18-65 years) with IBS-D. In this randomised, double-blind, placebo-controlled pilot study, 61 participants were recruited and assessed for changes in abdominal pain intensity (Numeric Rating Scale, NRS) and stool consistency (Bristol Stool Form Scale, BSFS) over a 4-week intervention period, with secondary outcomes including responder rates for IBS Global Assessment of Improvement (IBS-GAI) and perceived stress (Perceived Stress Scale, PSS). The probiotic group showed significantly higher overall responder rates for both abdominal pain and stool consistency ( P = 0.003) compared to the placebo group. Significant improvements were observed in abdominal pain ( P = 0.003) and stool consistency ( P = 0.035) scores in the probiotic versus placebo group from baseline to end of intervention. IBS-GAI responder rates were significantly higher among the probiotic versus placebo group ( P = 0.017) whilst perceived stress scores did not differ significantly between groups. In conclusion, supplementation with B. subtilis HU58 and H. faecalis SC208 for 4 weeks was safe and effective in improving stool consistency and abdominal pain in individuals with IBS-D, supporting its potential for symptom management in IBS-D. The trial is registered at https://ctri.nic.in/Clinicaltrials (CTRI/2022/07/044154).