Lactobacillus acidophilus

What is Lactobacillus acidophilus?

Lactobacillus acidophilus is one of the best-known probiotic species. It occurs naturally in the human gut, mouth and vagina, and it is used to make some yogurts and fermented milks. It has been sold as a supplement for decades, often for digestive comfort and, in women’s products, for vaginal health.

Like other lactobacilli, it produces lactic acid, which helps keep the vaginal environment mildly acidic. A healthy vaginal microbiome in women of reproductive age is usually dominated by one or a few Lactobacillus species, and loss of that dominance is linked to bacterial vaginosis and, in some studies, to a higher risk of urinary tract infections. That background is why lactobacilli appear in so many women’s wellness formulas.

What the research says

Research on L. acidophilus spans many strains and conditions, and the quality is uneven. A 2018 systematic review of strain specificity found that one particular mixture containing L. acidophilus CL1285 (with two other strains) had good evidence for preventing antibiotic-associated diarrhea in adults, while other lactobacillus strains did not show the same efficacy. For vaginal health, some trials have tested L. acidophilus, alone or in combinations, alongside antibiotics for bacterial vaginosis; a 2022 meta-analysis pooled such trials and found a modest improvement in cure rates when probiotics were added to antibiotics, but did not single out acidophilus as the driver.

For urinary health in general, the evidence for probiotics is weaker than marketing suggests. A 2015 Cochrane review of nine trials found no significant reduction in recurrent symptomatic UTIs with probiotics compared with placebo, and noted that most studies were small with a high risk of bias. For bacterial vaginosis, a 2022 meta-analysis of randomized trials found that adding probiotics to antibiotic treatment modestly improved cure rates, but the products, strains and routes (oral versus vaginal) varied widely.

A key point, emphasized by the NCCIH and by a large 2018 systematic review of strain specificity, is that results from one strain cannot be assumed to apply to another strain of the same species. A study of one commercial strain says little about a different strain with a different code on the label.

How it’s used in supplements

FemiCore lists the strain code LA85 but not the amount. We did not find published trials of this specific strain for bladder control or urinary health.

Probiotic doses are measured in colony forming units (CFU), typically ranging from about 1 billion to tens of billions per day in research. A label that lists strains only in milligrams, especially inside a combined blend, does not tell you how many live organisms you are getting or whether they survive to the end of shelf life. Look for products that state CFU at expiration, name the exact strain, and ideally cite trials of that strain.

Probiotics are generally well tolerated in healthy people. Mild gas or bloating in the first days is common. People who are seriously ill or have weakened immune systems face a small risk of serious infection and should talk to a doctor before using them.