Lactobacillus acidophilus (L. acidophilus)

Lactobacillus acidophilus is a species of Gram-positive, rod-shaped bacteria that is a natural inhabitant of the human gastrointestinal tract, mouth, and vagina (NIH, 2023). It is one of the most commonly used probiotics, functioning primarily by fermenting sugars into lactic acid, which lowers the local pH and inhibits the growth of pathogenic microorganisms (StatPearls, 2023). Beyond pH modulation, it produces antimicrobial substances like bacteriocins and competes with pathogens for mucosal binding sites, thereby enhancing the intestinal barrier (PubMed, 2022). Clinically, it is utilized to prevent and treat conditions such as antibiotic-associated diarrhea, irritable bowel syndrome (IBS), and bacterial vaginosis (Mayo Clinic, 2023). While it is generally recognized as safe, there are documented cases of bacteremia and endocarditis in immunocompromised or severely ill patients, highlighting a significant safety concern in specific populations (PubMed, 2021).

Other names

AcidophilusDöderlein's bacillusLactic acid bacteria

Lactobacillus acidophilus functions by fermenting dietary carbohydrates into lactic acid, which lowers the local pH and inhibits the growth of acid-sensitive pathogens (StatPearls, 2023). It also produces antimicrobial compounds such as bacteriocins and hydrogen peroxide, competes with pathogens for mucosal adhesion sites, and modulates the host immune response by inducing anti-inflammatory cytokines and strengthening epithelial tight junctions (PubMed, 2022).