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10 Benefits of Lactobacillus fermentum (L. fermentum)

Written by Biljana Novkovic, PhD | Last updated:
Jonathan Ritter
Medically reviewed by
Jonathan Ritter, PharmD, PhD (Pharmacology) | Written by Biljana Novkovic, PhD | Last updated:

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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) Is an Antioxidant

L. fermentum exhibits significant antioxidant properties [1, 2].

2) Increases Nutrient Bioavailability

L. fermentum was shown to increase the bioavailability of calcium, phosphorus, and zinc in fermented goat milk [3].

3) 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 [4].

L. fermentum modestly improved cholesterol in a clinical study [5].

4) 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 [6].

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 5 months after vaccination was decreased in the group that consumed this probiotic [7, 8].

L. fermentum Combats Bacteria

L. fermentum suppresses the growth of staphylococci, enterotoxigenic enterobacteria and Candida albicans [9]. It was shown to combat S. aureus and P. aeruginosa, common pathogens in hospital-acquired infections [10].

L. fermentum combats Streptococcus pneumoniae [11], Pseudomonas aeruginosa [12], S. typhimurium infection in mice [13,14] and Salmonella infection in mice [15].

L. fermentum alleviates pain and reduces the load of Staphylococcus in the breastmilk of women suffering from painful breastfeeding [16].

L. fermentum Alleviates Infections

L. fermentum reduces the duration and severity of respiratory illness in highly trained distance runners [17].

L. fermentum reduced the severity of gastrointestinal and respiratory illness symptoms in male but not female cyclists [18].

L. fermentum reduces gastrointestinal and upper respiratory tract infections in infants [19, 20].

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 [21].

5) May Alleviate Inflammation

Both live and dead L. fermentum have been demonstrated to attenuate the inflammatory process and diminish inflammatory mediators in laboratory experiments [22, 23].

L. fermentum can reduce inflammation of the upper small intestine in mice [24].

L. fermentum ameliorates the inflammatory response in colitis rats [25].

6) 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 [26].

7) Is Beneficial for the GI Tract

L. fermentum increases Lactobacillus, Bifidobacterium and Eubacterium levels in mice [27, 28].

L. fermentum normalizes the composition of gut microbiota and alleviates ampicillin-induced inflammation in the colon in mice [29].

L. fermentum alleviates constipation in mice [30, 31].

L. fermentum ameliorates ethanol-induced gastric injury in mice [32].

L. fermentum attenuates colitis and accelerates colitis recovery in mice and rats [33, 34, 35, 36].

8) May Improve Mood and Cognitive Function

L. fermentum reduces anxiety-like behavior and alleviates the ampicillin-induced impairment in memory retention in mice [29].

9) May Protect Against Liver Damage

L. fermentum significantly alleviates liver damage in alcoholic liver disease mice [37, 38].

Green tea extract and L. fermentum protect liver cells against ethanol exposure [39].

L. fermentum enhances the protective effect of Ssanghwa-tang (SHT), a traditional herbal medicine formula, on rat liver [40].

10) May Combat Urogenital Infections

L. fermentum inhibits both C. albicans and C. glabrata, the two most common pathogenic yeasts of humans, in the laboratory [41].

L. fermentum inhibits the growth of Gardnerella vaginalis [42] and E. coli [43] in mice.


  • Increases the activity of antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase [21].
  • Increases the IgG2a response over IgG1, indicating a Th1-biased humoral response [8, 21].
  • Increases IgA [6, 7, 44], and decreases IgE [21].
  • Increase in the proportion of natural killer (NK) cells [7].
  • Increases IFN-γ [8, 21, 6, 17] (a study where it was decreased: [14]).
  • Increases IL-2 [6, 33] and decreases IL-6 [33] and IL-8 [23].
  • Both increases [33] and decreases IL-4 [21, 6].
  • Both increases [14, 15, 37] and decreases IL-10 [21, 6].
  • Decreases IL-1β, TNF-α, and iNOS [22, 25, 37 ].
  • Decreases Rac, p38, and NF-kappaB activation [23].
  • Increases occludin, EGF, EGFR, VEGF, Fit-1, IκB-α, nNOS, eNOS, Mn-SOD, Cu/Zn-SOD, CAT [32].
  • Increases PGE2 [33, 37].
  • Stimulates mucosal immunity, by stimulating tracheal lymphocyte proliferation and increasing lung macrophage population [45].
  • Elevates mineralocorticoid and N-methyl-D-aspartate receptors in the hippocampus after ampicillin treatment [29].


L. fermentum is commonly found in fermented food products and is considered a “generally recognized as safe” (GRAS) organism by the US FDA [46]. It was found to be safe in infants and children [47, 48].

However, in immunocompromised individuals, it can lead to bacteremia [49]. 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 [50].

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About the Author

Biljana Novkovic

Biljana Novkovic

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 and 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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