The Improvement Effects of Weizmannia coagulans BC99 on Liver Function and Gut Microbiota of Long-Term Alcohol Drinkers: A Randomized Double-Blind Clinical Trial

Background/Objectives: With the improvement of living standards, alcoholic liver disease caused by long-term drinking has been a common multiple disease. Probiotic interventions may help mitigate liver damage caused by alcohol intake, but the mechanisms need more investigation. Methods: This study involved 70 long-term alcohol drinkers (18-65 years old, alcohol consumption >= 20 g/day, lasting for more than one year) who were randomly assigned to either the BC99 group or the placebo group. Two groups were given BC99 (3 g/day, 1 x 1010 CFU) or placebo (3 g/day) for 60 days, respectively. Before and after the intervention, blood routine indicators, liver function, renal function, inflammatory factors and intestinal flora were evaluated. Results: The results showed that intervention with Weizmannia coagulans BC99 reduced the levels of alanine aminotransferase, aspartate aminotransferase, glutamyl transpeptidase, serum total bilirubin, blood urea nitrogen, uric acid and 'blood urea nitrogen/creatinine'. Weizmannia coagulans BC99 also reduced the levels of pro-inflammatory factors TNF-alpha and IL-6 and increased the levels of anti-inflammatory factor IL-10. The results of intestinal flora analysis showed that Weizmannia coagulans BC99 regulated the imbalance of intestinal flora, increased the beneficial bacteria abundance (Prevotella, Faecalibacterium and Roseburia) and reduced the conditionally pathogenic bacteria abundance (Escherichia-Shigella and Klebsiella). Both LEfSe analysis and random forest analysis indicated that the increase in the abundance of Muribaculaceae induced by BC99 was a key factor in alleviating alcohol-induced liver damage. Conclusions: These findings demonstrate that Weizmannia coagulans BC99 has the potential to alleviate alcoholic liver injury and provide an effective strategy for liver protection in long-term drinkers.