Evidence supporting the use of: Lactobacillus acidophilus
For the health condition: Urinary Tract Infections

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Synopsis

Source of validity: Scientific
Rating (out of 5): 2

Lactobacillus acidophilus is a probiotic bacterium that has been studied for its potential role in the prevention and adjunctive treatment of urinary tract infections (UTIs), particularly in women. Scientific interest is based on the hypothesis that introducing or restoring beneficial Lactobacillus species to the vaginal or periurethral flora can help inhibit the colonization and growth of uropathogenic bacteria, such as Escherichia coli. Mechanisms proposed include lowering vaginal pH via lactic acid production, competing for adhesion sites, and producing antimicrobial substances (e.g., bacteriocins, hydrogen peroxide).

Clinical evidence, however, remains modest. Several small randomized controlled trials and observational studies have evaluated oral and intravaginal administration of L. acidophilus and related strains. For example, a 2008 Cochrane review concluded that while some studies suggested a reduction in UTI recurrence with probiotics, the evidence was not strong or consistent, with methodological limitations and often small sample sizes. More recent studies and meta-analyses similarly find only modest or inconclusive benefit for UTI prevention, and no robust evidence for treatment of acute infections.

Overall, while there is a plausible biological rationale and some scientific support for L. acidophilus in UTI prevention—especially as an adjunct to conventional therapy—the evidence is not strong, and guidelines do not currently recommend it as a primary therapy. Its use is best characterized as scientifically investigated but with weak supporting evidence (rating: 2/5).

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