Roll Call

“Lactobacillus?”Here!a probiotic bacteria genus

Biotech

Hasn’t appeared in a scanned product yet.

As a supplement

Talk to your doctor or pharmacist.

Roll Call does not check drug interactions or assess personal safety.

A large genus of bacteria naturally found in the human gut and in fermented foods like yogurt. Supplement labels often list just the genus name, though probiotic effects are generally tied to specific strains within it rather than the genus as a whole.

Why it’s used

Taken to support gut and digestive health, and sometimes for general immune support.

What the evidence says

The NIH Office of Dietary Supplements notes that probiotic research is strain-specific: a benefit shown for one Lactobacillus strain does not necessarily apply to another, even within the same species. When a label lists only the genus without a strain designation, it is difficult to match it to any particular clinical trial, which limits what can be said about that specific product.

Context

Clinical trials that have shown benefits, such as for certain types of diarrhea, used specific named strains (for example Lactobacillus rhamnosus GG) at specific colony-forming-unit counts, not the genus in general.

Rumors

  1. Lactobacillus supplements support gut health, digestion and immune function.

    Not gradedhealth and safety evidence

    Sources cited — no verdict reached.

    What was measured is not yet noted.

    Who’s saying this

    • Lucy Bee — a brand: sells organic skincare, self-tan and wellness products
      How we know who this is
      • “We launched Lucy Bee with our organic, fair trade Coconut Oil in 2012.” (their page)

  2. Lactobacillus supplements can cause infections in people with weakened immune systems.

    We haven’t found evidence strong enough to support this or rule it out.

    What was measured is not yet noted.

    Who’s saying this

    • WebMD — a publisher: health information publisher; an Internet Brands company
      How we know who this is
      • “As a leader in digital health publishing for more than 25 years, WebMD strives to maintain the most comprehensive and reliable source of health and medical information on the internet.” (their page)
      • “© 2005 - 2026 WebMD LLC, an Internet Brands company.” (their page)

  3. Lactobacillus probiotics cause brain fog and bloating by producing D-lactic acid in the small intestine.

    Does not support — suggestivehealth and safety evidence

    Studied in: patients with suspected SIBO and brain fogginess (Rao et al. cohort).

    Measured as a biomarker.

    Who’s saying this

    • Newsweek — a publisher: news magazine; owned by Dev Pragad and Johnathan Davis
      How we know who this is
      • “Newsweek is committed to fair, independent, and transparent journalism.” (their page)
      • “CEO and President Dev Pragad and Johnathan Davis each own 50 percent of Newsweek.” (their page)

  4. Lactobacillus treats and prevents diarrhea, including rotavirus, travelers' and antibiotic-associated diarrhea.

    Unresolvedhealth and safety evidence

    Studied in: children (receiving antibiotics or with acute gastroenteritis).

    Measured as an outcome.

    Who’s saying this

    • WebMD — a publisher: health information publisher; an Internet Brands company
      How we know who this is
      • “As a leader in digital health publishing for more than 25 years, WebMD strives to maintain the most comprehensive and reliable source of health and medical information on the internet.” (their page)
      • “© 2005 - 2026 WebMD LLC, an Internet Brands company.” (their page)

  5. Regularly taking Lactobacillus prevents infections, including vaginal and urinary infections, by restoring the body's bacterial balance.

    We haven’t found evidence strong enough to support this or rule it out.

    What was measured is not yet noted.

    Who’s saying this

    • Intimate Rose — a brand: sells pelvic health tools such as dilators and pelvic wands
      How we know who this is
      • “Dr. Amanda’s expertise combined with the innovation of Aaron Wilt, CEO of Intimate Rose, resulted in the creation of the Intimate Rose dilators and pelvic wand.” (their page)