Lactobacillus acidophilus is a nonpathogenic bacteria that inhabits the gastrointestinal tract, where it aids in digestion and in the production of some B vitamins such as biotin.
Fermented dairy foods such as live culture yogurt and fermented milk are good sources of acidophilus. Supplemental acidophilus is available in liquid, powder, capsule, and tablet form.
Recommendations for acidophilus intake vary with individual intestinal microflora profiles. Acidophilus supplements appear to be very safe, with no known side effects even with large intakes of acidophilus.