L. casei has antioxidant effects. This probiotic combats stress, boost immunity, reduces inflammation, ameliorates arthritis and type 2 diabetes, and combats breast, colorectal and other types of cancer.

What is Lactobacillus casei?

Lactobacillus casei  is a Gram-positive, nonpathogenic lactic acid bacterium (R). It is found in fermented dairy products (e.g. cheese), plant materials (e.g. wine, pickles) and in the reproductive and gastrointestinal tracts of humans and animals (R,R).

As a nutritional supplement, L. casei  has been shown to improve intestinal microbial balance, arthritis, type 2 diabetes and to have anti-cancer properties (R).

Health Benefits of L. casei

1) L. casei  Acts as an Antioxidant

L. casei  combined with prebiotic inulin has a positive influence on human plasma antioxidant capacity (R).

Treatment with L. casei  reduced oxidative stress caused by aflatoxin and induced a significant improvement in all the biochemical and histological liver parameters in rats (R).

2) L. casei  Combats Stress

L. casei  lowered academic stress-induced increases in cortisol and the incidence of physical symptoms in students. In rats, L. casei  suppressed blood corticosterone levels (R).

Similarly, when L. casei  was administered to medical students undertaking an authorized nationwide examination to test their response to stress, this bacterium increased serotonin levels, lowered the rate of subjects experiencing common abdominal and cold symptoms and decreased the total number of days students experienced these symptoms (R).

3) L. casei  Boosts Immunity

L. casei  enhances the immune system during its transit in the digestive tract (R,R), and was shown to stimulates nitric oxide, cytokine and prostaglandin production (R).

L. casei  promotes the recovery of immunosuppression caused by chemotherapeutic agents in mice, by activating natural killer (NK) cells, cytotoxic T cells and macrophages (R). These are all white blood cells that recognize and eliminate tumor cells and infected cells.

L. casei  Combats Respiratory and Gastrointestinal Infections

While some studies find no evidence that consuming L. casei  protects against respiratory symptoms (R), many others show that L. casei  is beneficial in both respiratory and gastrointestinal infections.

L. casei  significantly lowered the incidence and duration of upper respiratory tract infections (URTIs) in healthy middle-aged office workers (R).

Similarly, in healthy shift workers, L. casei  decreased the incidence of gastrointestinal and respiratory common infectious disease (CIDs), increased the time to the first occurrence of CID, and reduced the total number of CIDs in the subgroup of smokers. In the course of CID, the total duration of fever was lower and an increase in leukocyte, neutrophil, and natural killer (NK) cell counts and activity was observed (R).

L. casei  also lowered the incidence of common infectious diseases (CIDs) in children (R), and decreased the duration of CID, and especially upper-respiratory-tract infections (URTI) such as rhinopharyngitis in the elderly (R).

In athletic men and women who engaged in endurance-based physical activities in winter, L. casei  lowered the proportion of subjects who experienced 1 or more weeks with upper-respiratory-tract infection (URTI) symptoms, and decreased the number of URTI episodes (R).

Administration of the probiotic L. casei  in conjunction with albendazole reduced the Giardia infection and enhanced recovery in mice (R).

L. casei  is Beneficial in Viral Infections

Continuous intake of L. casei  contributes to the alleviation of fever caused by norovirus gastroenteritis by correcting the imbalance of the intestinal microflora in the elderly (R).

L. casei  Combats Parasites

Frequent treatment of mice with L. casei  induces total protection against infection with of Trichinella spiralis parasite worms (R).

L. casei  is Beneficial in Pregnancy

The intake of milk fermented with L. casei  during the lactation period modestly contributes to the modulation of the mother’s immunological response after delivery, and decreases the incidence of gastrointestinal episodes in the breastfed child (R).

4) L. casei  Reduces Inflammation

L. casei  acts as an anti-inflammatory agent (R). It was shown that this bacterium has anti-inflammatory effects when it is administered as a supplement in mice fed a high-fat-diet (R).

L. casei  increases the prevalence of Lactobacilli in mice microbiota, and alters the expression of cytokines in a manner consistent with an anti-inflammatory response (R).

Lactobacillus casei  improved natural killer (NK) cell activity and produced a more anti-inflammatory cytokine profile in healthy non-immunocompromised elderly subjects (R).

L. casei protects mice from anaphylaxis (acute allergic inflammation) and arthritis (autoimmune inflammation) (R).

Live L. casei  can counteract the proinflammatory effects of E. coli on Crohn’s disease inflamed mucosa by specific downregulation of proinflammatory cytokines (R,R).

5) L. casei  Prevents Arthritis

L. casei  supplementation helps alleviate symptoms and improve inflammatory cytokines in women with rheumatoid arthritis (R).

L. casei  protects mice from autoimmune arthritis (R), and consumption of L. casei  prior to infection abolishes intestinal and joint inflammation triggered by Salmonella in mice (R).

L. casei  positively contributes to osteoarthritis treatment in rats, by reducing pain, inflammatory responses, and articular cartilage degradation. L. casei  together with glucosamine decreased expression of various pro-inflammatory cytokines and matrix metalloproteinases, while up-regulating anti-inflammatory cytokines (R).

Similarly, L. casei  effectively suppressed symptoms of rheumatoid arthritis in rats, paw swelling, lymphocyte infiltration and destruction of cartilage tissues. Anti-inflammatory cytokines were increased, while pro-inflammatory cytokines were decreased (R,R,R).

6) L. casei  May Alleviate Dermatitis

A L. casei  protein P14 reduces symptoms of atopic dermatitis in mice (R).

7) L. casei  Ameliorates Allergies

Volunteers with seasonal allergic rhinitis treated with L. casei  showed a significant reduction in levels of antigen-induced cytokines, showing that probiotic supplementation modulates immune responses in allergic rhinitis and may have the potential to alleviate the severity of symptoms (R).

L. casei  protects mice from acute allergic inflammation (anaphylaxis) (R).

Following airway allergen administration, mice fed L. casei  showed evidence of attenuation of lung inflammation, as well as reductions in proinflammatory cytokines (R).

8) L. casei  May Protect against Candida

The addition of L. casei  to the diet of mice improves survival and resistance against C. albicans infection. This bacterium normalizes the immune response, allowing efficient recruitment and activation of phagocytes, as well as the effective release of pro-inflammatory cytokines (R).

Even heat-killed L. casei  protects immunodeficient mice against C. albicans (R).

9) L. casei  Improves Dental Health

Oral administration of L. casei  reduced the number of pathogenic (periodontopathic) bacteria in healthy volunteers with mild to moderate gum inflammation (periodontitis) (R).

10) L. casei  is Beneficial in Cardiovascular Disease

L. casei  improves insulin sensitivity index in humans, an important risk factor for cardiovascular morbidity, especially stroke and coronary heart disease and mortality (R).

L. casei  was shown to reduce cholesterol in laboratory experiments (R).

11) L. casei  Combats Obesity

L. casei  supplementation improves body weight in rats fed a high-fat diet (R).

L. casei  has anti-inflammatory effects when it is administered as a supplement in mice fed a high-fat-diet (R).

L. casei  improves insulin resistance and glucose intolerance in mice with diet-induced obesity (R).

12) L. casei  May be Beneficial in Diabetes

L. casei  attenuates the hyperglycemic response to glucose and blood glycerol levels in rats (R).

Furthermore, long‐term ingestion of L. casei  ameliorates insulin resistance and glucose intolerance in rats fed a high‐fat diet (R), rats with hyperinsulinemia (R),  and obese mice (R).

L. casei  significantly lowers blood levels of pro-inflammatory cytokines and neutrophils in diabetic rats, lowering a risk of diabetes mellitus and its complications (R).

L. casei  significantly improved glucose intolerance, dyslipidemia, immune-regulatory properties, and oxidative stress in mice with type 2 diabetes (R).

13) L. casei  is Beneficial for the GI Tract

L. casei  Alters the Composition of Intestinal Microbiota

L. casei  consumption alters the composition and diversity of human intestinal microbiota. There is a positive correlation between L. casei and Prevotella, Lactobacillus, Faecalibacterium, Propionibacterium, Bifidobacterium and some Bacteroidaceae and Lachnospiraceae, and a negative correlation with the presence of Clostridium, Phascolarctobacterium, Serratia, Enterococcus, Shigella and Shewanella (R).

L. casei  suppressed potentially harmful Pseudomonas and Acinetobacter in volunteers (R).

Fermented milk containing L. casei  preserved the diversity of the gut microbiota, relieved abdominal dysfunction, and prevented an increase in cortisol levels in healthy medical students exposed to academic stress (R).

L. casei  Ameliorates Constipation and Diarrhea

Continuous consumption of fermented milk containing L. casei  alleviates constipation-related symptoms, provides satisfactory bowel habit and results in earlier recovery from hemorrhoids in women after childbirth (R).

A fermented milk beverage containing L. casei  relieved irregular bowel movement in gastrectomized patients. It reduced the degree of constipation and improved diarrhea (R).

L. casei  intake was associated with a decreased risk of antibiotic-associated diarrhea in patients (R,R).

L. casei  reduces the incidence, duration, and severity of diarrhea in children (R,R).

L. casei  prevents constipation in mice (R).

L. casei  is Beneficial in Intestinal Injury and Inflammation

L. casei  is effective for the treatment of aspirin-associated small bowel injury (R).

L. casei  induced complete recovery in mice with enteropathy (such as Coeliac disease) (R).

L. casei  is very effective in ameliorating colitis in rats (R) and mice (R).

L. casei  Ameliorates IBD

L. casei  decreases the severity of intestinal inflammation in mice with inflammatory bowel disease (IBD) (R).

L. casei  can counteract the pro-inflammatory effects of E. coli on Crohn’s disease inflamed mucosa by downregulating proinflammatory cytokines (R).

14) L. casei  May be Effective Against H. pylori

L. casei  was effective against H. pylori in laboratory experiments (R).

15) L. casei  May Boost Liver Function

L. casei  attenuates alcohol-induced liver cell damage (R).

In chronic alcohol-induced mice, whey fermented with L. casei  significantly attenuated the increased levels of alanine aminotransferase, aspartate aminotransferase, and triglyceride levels, increased antioxidant activity, and improved liver parameters (R).

L. casei  protects against the onset of non-alcoholic fatty liver disease (NAFLD) in a mice (R), and suppresses nonalcoholic steatohepatitis development, by reducing blood lipopolysaccharide concentrations, suppressing inflammation and fibrosis in the liver, and reducing colon inflammation (R).

L. casei  significantly improved the survival of rats with liver injury, via its anti-oxidative and anti-inflammatory capacities (R).

In rats with acute liver failure, L. casei  inhibits pro-inflammatory cytokines, attenuates hepatic inflammation, prevents intestinal injury and modulates the intestinal microbiota by increasing Lactobacillus and Bifidobacterium levels (R).

16) L. casei  Combats Cancer

L. casei  has considerable antitumor activity, mainly by activating macrophages, modulating host’s immune response and regulating tumor cell death (R). L. casei exhibits cytotoxic activity against various tumor cells (R).

L. casei  is able to suppress the growth of adult T-cell leukemia cells, acute lymphoblastic leukemia cells and promonocytic leukemia cells (R).

L. casei  extract killed gastric cancer cells (R), and decreased the viability of liver cancer cells by 77% (R).

L. casei  decreased cell migration and invasion of colorectal cancer cells (R,R), inhibited human and mouse colon cancer cell growth, and resulted in an 80% reduction in tumor volume of treated mice (R).

Administration of milk fermented by L. casei  delayed and suppressed tumor growth in mice with breast cancer, both when it was administered preventively and as a treatment. L. casei  further reduced tumor vascularity and lung metastasis, and prolonged survival (R,R,R).

L. casei  decreased breast tumor volume and tumor vascularity in rats (R).

Consumption of soy isoflavones in combination with L. casei  decreased the risk of breast cancer among Japanese women (R).

L. casei  administration significantly reduced the recurrence rate of bladder cancer and colorectal cancer in cancer patients (R).

17) L. casei  Combats Toxins

L. casei  can bind to heterocyclic aromatic amines and can decrease their concentration and their toxicity (R).

L. casei  decreases the cytotoxic effects of pesticides on human cells (R).

L. casei  supplementation reduces the level of aflatoxin in blood, and can improve the adverse effect on body weight and blood parameters in rats (R).

A fermented milk drink containing L. casei  may reduce aflatoxin toxicity in humans (R).

18) L. casei  May Help with Histamine Intolerance

L. casei  degrades biogenic amines (BAs) and reduces histamine and tyramine accumulation in cheese (R).

19) L. casei  is Beneficial in Smokers

Cigarette smoking reduces natural killer (NK) activity. L. casei  intake prevented the smoke-dependent NK activity reduction in Italian male smokers (R).

20) L. casei  May Improve Cognitive Performance

L. casei  potentiated the effect of proanthocyanidins extracted from lotus seedpod, ameliorated memory impairment in mice, and improved total antioxidant capacity level (R).


  • L. casei decreases pro-inflammatory cytokines such as TNF-α, IFN-γ, interleukins IL-2, IL-6, IL-8, IL-17, IL-23, IL-1β (R,R,R,R,R).
  • L. casei increases anti-inflammatory cytokines such as IL-10 (R,R).
  • L. casei inhibits nuclear factor NF-κB (R).
  • L. casei may even prevent inflammation in patients who have already synthesized specific IgE or autoantibodies (R).


L. casei  is generally well tolerated. Use of probiotics should be avoided in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms.

Buy Lactobacillus casei

The following probiotics have L. casei in them:

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.

Click here to subscribe


1 Star2 Stars3 Stars4 Stars5 Stars
(4 votes, average: 3.75 out of 5)

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.