L. fermentum  is one of the less studied probiotic strains that shows many promising health benefits, such as boosting the immune response, improving liver health and lowering cholesterol levels.

What is Lactobacillus fermentum?

Lactobacillus fermentum  is a Gram-positive lactic acid bacterium, commonly found in fermenting animal and plant material. It is also commonly found as a component of the human microbiota.

Health Benefits of L. fermentum

1) L. fermentum  is an Antioxidant

L. fermentum  exhibits significant antioxidant properties (R,R).

2) L. fermentum  Increases Nutrient Bioavailability

L. fermentum  was shown to increase the bioavailability of calcium, phosphorus, and zinc in fermented goat milk (R).

3) L. fermentum  Lowers Cholesterol

L. fermentum  reduces total blood cholesterol, total triglyceride levels and low-density lipoprotein (LDL) cholesterol in mice. It also decreased body weight and liver weight/body weight ratio (R).

L. fermentum  modestly improved cholesterol in a clinical study (R).

4) L. fermentum  Boosts Immunity

L. fermentum  Combats Viruses

L. fermentum  improves resistance against lethal influenza infection in both mice and chicken, by activating the Th1 response and augmenting IgA production (R).

Oral administration of L. fermentum  potentates the immunologic response of an anti-influenza vaccine and may provide enhanced systemic protection by increasing the Th1 response and virus-neutralizing antibodies. The incidence of an influenza-like illness during 5 months after vaccination was decreased in the group that consumed this probiotic (R,R).

L. fermentum  Combats Bacteria

L. fermentum  suppresses the growth of staphylococci, enterotoxigenic enterobacteria and Candida albicans (R). It was shown to combat S. aureus and P. aeruginosa, common pathogens in hospital-acquired infections (R).

L. fermentum  combats Streptococcus pneumoniae (R), Pseudomonas aeruginosa (R), S. typhimurium infection in mice (R,R) and Salmonella infection in mice (R).

L. fermentum  alleviates pain and reduces the load of Staphylococcus in the breastmilk of women suffering from painful breastfeeding (R).

L. fermentum  Alleviates Infections

L. fermentum  reduces the duration and severity of respiratory illness in highly trained distance runners (R).

L. fermentum  reduced the severity of gastrointestinal and respiratory illness symptoms in male but not female cyclists (R).

L. fermentum  reduces gastrointestinal and upper respiratory tract infections in infants (R,R).

L. fermentum  May be Beneficial in Aging

L. fermentum  alleviates immunosenescence by enhancing antioxidant enzyme activities, and was shown to reduce E. coli infection in aging mice (R).

5) L. fermentum  May Alleviate Inflammation

Both live and dead L. fermentum have been demonstrated to attenuate the inflammatory process and diminish inflammatory mediators in laboratory experiments (R,R).

L. fermentum can reduce inflammation of the upper small intestine in mice (R).

L. fermentum ameliorates the inflammatory response in colitic rats (R).

6) L. fermentum  May Increase Lactose Tolerance

L. fermentum  degrades αS1-casein and lowers the recognition and the binding of this casein to IgE from the blood of patients with cow’s milk allergy (R).

7) L. fermentum  is Beneficial for the GI Tract

L. fermentum  increases Lactobacillus, Bifidobacterium and Eubacterium levels in mice (R,R).

L. fermentum  normalizes the composition of gut microbiota and alleviates ampicillin-induced inflammation in the colon in mice (R).

L. fermentum  alleviates constipation in mice (R,R).

L. fermentum  ameliorates ethanol-induced gastric injury in mice (R).

L. fermentum  attenuates colitis and accelerates colitis recovery in mice and rats (R,R,R,R).

8) L. fermentum  May Improve Mood and Cognitive Function

L. fermentum  reduces anxiety-like behavior and alleviates the ampicillin-induced impairment in memory retention in mice (R).

9) L. fermentum  May Protect Against Liver Damage

L. fermentum  significantly alleviates liver damage in alcoholic liver disease mice (R,R).

Green tea extract and L. fermentum  protect liver cells against ethanol exposure (R).

L. fermentum  enhances the protective effect of Ssanghwa-tang (SHT), a traditional herbal medicine formula, on rat liver (R).

10) L. fermentum  May Combat Urogenital Infections

L. fermentum  inhibits both C. albicans and C. glabrata, the two most common pathogenic yeasts of humans, in the laboratory (R).

L. fermentum  inhibits the growth of Gardnerella vaginalis (R) and E. coli (R) in mice.


  • L. fermentum  increases the activity of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase (R).
  • L. fermentum  increases the IgG2a response over IgG1, indicating a Th1-biased humoral response (R,R).
  • L. fermentum  increases IgA (R,R,R), and decreases IgE (R).
  • L. fermentum  increase in the proportion of natural killer (NK) cells (R).
  • L. fermentum  increases IFN-γ (R,R,R,R) (a study where it was decreased: (R)).
  • L. fermentum  increases IL-2 (R,R) and decreases IL-6 (R) and IL-8 (R).
  • L. fermentum  both increases (R) and decreases IL-4 (R,R).
  • L. fermentum  both increases (R,R,R) and decreases IL-10 (R,R).
  • L. fermentum  decreases IL-1β, TNF-α, and iNOS (R,R,R).
  • L. fermentum  decreases Rac, p38, and NF-kappaB activation (R).
  • L. fermentum  increases occludin, EGF, EGFR, VEGF, Fit-1, IκB-α, nNOS, eNOS, Mn-SOD, Cu/Zn-SOD, CAT (R).
  • L. fermentum  increases PGE2 (R,R).
  • L. fermentum  stimulates mucosal immunity, by stimulating tracheal lymphocyte proliferation and increasing lung macrophage population (R).
  • L. fermentum  elevates mineralocorticoid and N-methyl-D-aspartate receptors in the hippocampus after ampicillin treatment (R).


L. fermentum  is commonly found in fermented food products and is considered a “generally recognized as safe” (GRAS) organism by the US FDA (R). It was found to be safe in infants and children (R,R).

However, in immunocompromised individuals, it can lead to bacteremia (R). Use of probiotics in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms should be avoided.

A strain of L. fermentum  AGR1487 causes a pro-inflammatory response in the host and should be avoided (R).

About the Author

Biljana Novkovic - PHD (ECOLOGICAL GENETICS) - Writer at Selfhacked

Dr. Biljana Novkovic, PhD


Biljana received her PhD from Hokkaido University.

Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science & health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.

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