BDNF and Constipation: 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.