Weizmannia coagulans BC99 Relieves Constipation Symptoms by Regulating Inflammatory, Neurotransmitter, and Lipid Metabolic Pathways: A Randomized, Double-Blind, Placebo-Controlled Trial

Probiotics have attracted increasing attention due to their benefits in terms of relieving gastrointestinal ailments, including constipation. This study evaluated the potential of <i>Weizmannia coagulans</i> BC99 for clinical remission of constipation in adults. In this randomized, double-blind, and placebo-controlled trial, 90 individuals with constipation were divided between a BC99 and a placebo group for an 8-week intervention duration. The spontaneous bowel movement (SBM) frequency, patient assessment of constipation symptoms (PAC-SYM), patient assessment of constipation quality of life (PAC-QOL), inflammatory cytokines, neurotransmitters, and serum metabolites were investigated before and after the intervention. The results showed that BC99 intervention significantly improved constipation symptoms and quality of life in adults with constipation, as evidenced by an increased SBM score and decreased PAC-SYM and PAC-QOL scores. Additionally, BC99 supplementation increased the levels of neurotransmitters (5-HT, MTL, AChE, and BDNF) associated with intestinal motility and alleviated inflammation in participants with constipation, as supported by higher levels of anti-inflammatory factors (IL-4, IL-10) and lower levels of pro-inflammatory factors (IL-6, IFN-γ) in the BC99 group. Furthermore, BC99 altered the abundance of 93 metabolites and affected biological pathways correlated with gastrointestinal motility, including sphingolipid metabolism, steroid hormone biosynthesis, and glycerophospholipid metabolism. This study demonstrates the effectiveness of the <i>W. coagulans</i> BC99 strain in relieving constipation in adults, and reveals its potential mechanism of action. These findings provide a scientific basis for BC99 as an effective and safe probiotic for constipation treatment.