What is Lactobacillus casei?
Lactobacillus casei is a Gram-positive, nonpathogenic lactic acid bacterium . 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 [2, 3].
As a nutritional supplement, Lactobacillus casei has been shown to improve intestinal microbial balance, arthritis, type 2 diabetes and to have anti-cancer properties .
Health Benefits of L. casei
1) Acts as an Antioxidant
L. casei combined with prebiotic inulin has a positive influence on human plasma antioxidant capacity .
2) Combats Stress
L. casei lowered academic stress-induced increases in cortisol and the incidence of physical symptoms in students. In rats, Lactobacillus casei suppressed blood corticosterone levels .
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 .
3) Boosts Immunity
L. casei promotes the recovery of immunosuppression caused by chemotherapeutic agents in mice, by activating natural killer (NK) cells, cytotoxic T cells and macrophages . 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 , 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 .
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 .
L. casei also lowered the incidence of common infectious diseases (CIDs) in children , decreased the duration of CID, and especially lessened upper-respiratory-tract infections (URTI) such as rhinopharyngitis in the elderly .
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 .
Administration of the probiotic L. casei in conjunction with albendazole reduced the Giardia infection and enhanced recovery in mice .
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 .
L. casei Combats Parasites
Frequent treatment of mice with L. casei induces total protection against infection with of Trichinella spiralis parasite worms .
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 .
4) Reduces Inflammation
L. casei improved natural killer (NK) cell activity and produced a more anti-inflammatory cytokine profile in healthy non-immunocompromised elderly subjects .
L. casei protects mice from anaphylaxis (acute allergic inflammation) and arthritis (autoimmune inflammation) .
5) Prevents Arthritis
L. casei supplementation helps alleviate symptoms and improve inflammatory cytokines in women with rheumatoid arthritis .
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 .
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 [30, 31, 32].
6) May Alleviate Dermatitis
An L. casei protein P14 reduces symptoms of atopic dermatitis in mice .
7) 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 .
L. casei protects mice from acute allergic inflammation (anaphylaxis) .
Following airway allergen administration, mice fed L. casei showed evidence of attenuation of lung inflammation, as well as reductions in proinflammatory cytokines .
8) 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 .
Even heat-killed L. casei protects immunodeficient mice against C. albicans .
9) 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) .
10) 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  and was shown to reduce cholesterol in laboratory experiments .
11) Combats Obesity
12) May be Beneficial in Diabetes
L. casei attenuates the hyperglycemic response to glucose and blood glycerol levels in rats .
L. casei significantly lowers blood levels of pro-inflammatory cytokines and neutrophils in diabetic rats, lowering the risk of diabetes mellitus and its complications .
L. casei significantly improved glucose intolerance, dyslipidemia, immune-regulatory properties, and oxidative stress in mice with type 2 diabetes .
13) 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 .
L. casei suppressed potentially harmful Pseudomonas and Acinetobacter in volunteers .
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 .
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 .
A fermented milk beverage containing L. casei relieved irregular bowel movement in gastrectomized patients. It reduced the degree of constipation and improved diarrhea .
L. casei intake was associated with a decreased risk of antibiotic-associated diarrhea in patients [52, 53], reduces the incidence, duration, and severity of diarrhea in children [54, 9], and prevents constipation in mice .
L. casei is Beneficial in Intestinal Injury and Inflammation
L. casei is effective for the treatment of aspirin-associated small bowel injury , induced complete recovery in mice with enteropathy (such as Coeliac disease) , and is very effective in ameliorating colitis in rats  and mice .
L. casei Ameliorates IBD
L. casei decreases the severity of intestinal inflammation in mice with inflammatory bowel disease (IBD)  and can counteract the pro-inflammatory effects of E. coli on Crohn’s disease inflamed mucosa by downregulating proinflammatory cytokines .
14) May be Effective Against H. pylori
L. casei was effective against H. pylori in laboratory experiments .
15) May Boost Liver Function
L. casei attenuates alcohol-induced liver cell damage .
In chronic alcohol-induced mice, whey fermented with L. casei significantly attenuated the increased levels of alanine aminotransferase, aspartate aminotransferase, and triglycerides; increased antioxidant activity; and improved liver parameters .
L. casei protects against the onset of non-alcoholic fatty liver disease (NAFLD) in mice , and suppresses nonalcoholic steatohepatitis development, by reducing blood lipopolysaccharide concentrations, suppressing inflammation and fibrosis in the liver, and reducing colon inflammation .
L. casei significantly improved the survival of rats with liver injury, via its anti-oxidative and anti-inflammatory capacities .
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 .
16) Combats Cancer
L. casei has considerable antitumor activity, mainly by activating macrophages, modulating host’s immune response and regulating tumor cell death . L. casei exhibits cytotoxic activity against various tumor cells .
L. casei is able to suppress the growth of adult T-cell leukemia cells, acute lymphoblastic leukemia cells and promonocytic leukemia cells .
L. casei decreased cell migration and invasion of colorectal cancer cells [70, 71], inhibited human and mouse colon cancer cell growth, and resulted in an 80% reduction in tumor volume of treated mice .
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 [73, 74, 75].
L. casei decreased breast tumor volume and tumor vascularity in rats .
Consumption of soy isoflavones in combination with L. casei decreased the risk of breast cancer among Japanese women .
L. casei administration significantly reduced the recurrence rate of bladder cancer and colorectal cancer in cancer patients .
17) Combats Toxins
Lactobacillus casei can bind to heterocyclic aromatic amines and can decrease their concentration and their toxicity .
Lactobacillus casei decreases the cytotoxic effects of pesticides on human cells .
Lactobacillus casei supplementation reduces the level of aflatoxin in blood and can improve the adverse effect on body weight and blood parameters in rats .
A fermented milk drink containing Lactobacillus casei may reduce aflatoxin toxicity in humans .
18) May Help with Histamine Intolerance
19) Beneficial in Smokers
Cigarette smoking reduces natural killer (NK) activity. L. casei intake prevented the smoke-dependent NK activity reduction in Italian male smokers .
20) 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 .
- Decreases pro-inflammatory cytokines such as TNF-α, IFN-γ, interleukins IL-2, IL-6, IL-8, IL-17, IL-23, IL-1β [3, 24, 23, 27, 9].
- Increases anti-inflammatory cytokines such as IL-10 [3, 23].
- Inhibits nuclear factor NF-κB .
- May even prevent inflammation in patients who have already synthesized specific IgE or autoantibodies .
Lactobacillus casei is generally well tolerated. Use of probiotics should be avoided in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms.
The following probiotics have L. casei in them:
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