Lactobacillus casei (L. casei)

Lactobacillus casei (now formally reclassified as Lacticaseibacillus casei) is a species of Gram-positive, facultatively anaerobic bacteria that naturally inhabits the human gastrointestinal and reproductive tracts. In a pharmacological context, L. casei is not a discrete molecular target like a receptor or enzyme; rather, it is a whole organism utilized as a probiotic therapeutic agent. It is widely recognized for its ability to survive the transit through the stomach and colonize the intestines, where it contributes to microbial balance and suppresses the growth of enteric pathogens. Clinical applications focus on its efficacy in treating and preventing various forms of diarrhea, improving the symptoms of irritable bowel syndrome, and modulating the host's immune response. While generally recognized as safe (GRAS), it can act as an opportunistic pathogen in highly vulnerable populations, such as the elderly or those with advanced immunosuppression.

Other names

Lacticaseibacillus caseiBacillus caseiLactobacillus casei subsp. casei

As a probiotic, Lactobacillus casei exerts its effects through several mechanisms: it competes with pathogenic bacteria for nutrients and adhesion sites on the intestinal mucosa, produces antimicrobial substances such as lactic acid and bacteriocins that lower local pH, and interacts with host immune cells (like dendritic cells and macrophages) to modulate cytokine production (e.g., increasing IL-10). It also strengthens the intestinal epithelial barrier by upregulating tight junction proteins.