The gut microbe B. longum may improve the human immune response and help prevent gut disorders. Early evidence suggests that it may also suppress allergies, reduce cholesterol, and improve skin health. Learn more here.
Bifidobacterium longum is a Gram-positive, rod-shaped species of bacteria naturally present in the human GI tract. It’s subspecies B. longum subsp. infantis is one of the earliest bacteria to colonize the infant gut. B. longum is often added to food products as a probiotic with various health benefits.
B. longum probiotic supplements have not been approved by the FDA for medical use. Supplements generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing.
SelfDecode has an AI-powered app that allows you to see how B. longum benefits your personal genetic predispositions. These are all based on clinical trials. The red and sad faces denote an increased genetic risk of developing conditions that B. longum counteracts. B. longum may also help improve the sub-optimal homocysteine lab results that this user uploaded to SelfDecode’s Lab Test Analyzer.
B. longum ssp. infantis triggered the anti-poliovirus response in a small study of 20 infants .
B. longum ssp. infantis promoted the immune response in human volunteers .
B. longum also stimulated immune function in 45 elderly, hospitalized patients who received an influenza vaccine .
B. longum ssp. infantis had strong immunomodulatory effect in blood drawn from elderly patients, compared with other well-known commercial strains .
B. longum supplementation reduced the incidence of influenza and fever in 27 elderly subjects who received an influenza vaccine .
B. longum fed infants showed a trend toward fewer respiratory tract infections .
B. longum protected mice against pneumonia-induced death by finely tuning the inflammatory response and speeding up lung recovery .
B. longum ssp. infantis inhibited rotavirus infection in mice .
Oral administration of B. longum protects mice against gut-derived sepsis caused by P. aeruginosa .
B. longum improves survival in mice infected with Salmonella Typhimurium .
B. longum inhibits the growth of C. albicans and other pathogenic bacteria .
B. longum ssp. infantis reduced gastrointestinal symptoms in untreated Celiac disease (CD) patients .
B. longum attenuated the production of inflammatory cytokines and the CD4+ T-cell mediated immune response and protects newborn rats against gliadin (gluten)-induced enteropathy .
Enterotoxigenic Bacteroides fragilis (ETBF) strains have been suggested to be associated with acute and persistent diarrhea, inflammatory bowel disease and colorectal cancer. B. longum significantly decreased ETBF in humans .
B. longum modulated the intestinal environment and appeared to improve the general health care of elderly patients receiving enteral feeding .
B. longum maintained high Lactobacilli levels in mice .
B. longum ssp. infantis increased propionic, succinic acid, and butyric acid in rats .
Administration of B. longum ssp. infantis significantly reduced the incidence of necrotizing enterocolitis (NEC) and associated inflammation in rats .
B. longum improved colitis in mice .
B. longum ssp. infantis relieved many of the symptoms of IBS in a clinical trial involving women .
B. longum ameliorated ulcerative colitis symptoms in Japanese patients .
B. longum reduced visceral hypersensitivity in mice with IBS .
Researchers are currently investigating whether B. longum has other health benefits. The potential benefits in this section have produced positive results in at least one clinical trial, but these studies are small, contradictory, or otherwise limited. Talk to your doctor before supplementing with B. longum for any reason.
B. longum reduced inflammation and improved symptoms in patients with ulcerative colitis .
B. longum significantly alleviated inflammation in mice with gout .
Intake of yogurt or powder supplemented with B. longum alleviated subjective symptoms and affected blood markers of allergy in individuals with Japanese cedar pollinosis [42, 43, 44]. Nasal symptoms such as itching, rhinorrhea, and blockage as well as throat symptoms tended to be relieved with this probiotic .
Neonatal mother-to-offspring colonization with B. longum reduces allergic responses in mice .
B. longum reduced total cholesterol, particularly among subjects with moderate hypercholesterolemia .
B. longum supplementation significantly reduced total cholesterol, liver lipid deposition, and adipocyte size and positively affected liver and kidney function in hypercholesterolemic rats .
B. longum extract, when applied to the skin, was able to improve inflammation parameters, decrease skin sensitivity, increase skin resistance against physical and chemical aggression, and decrease skin dryness in volunteers with sensitive skin .
B. longum exerted photoprotective effects on the skin in mice .
B. longum and FOS improved biochemical parameters and neuropsychological tests in cirrhotic patients with minimal hepatic encephalopathy (MHE) .
Oral administration of B. longum decreased serum phosphate levels in 15 patients receiving hemodialysis (HD) .
No clinical evidence supports the use of B. longum for any of the conditions listed in this section. Below is a summary of the existing animal and cell-based research, which should guide further investigational efforts. However, the studies listed below should not be interpreted as supportive of any health benefit.
B. longum fed mice exhibited improved learning and memory .
Depression can be reversed in rats by administering B. infantis .
Daily administration of B. longum reduced schizophrenic rearing behavior in mice, decreased the resting level of plasma corticosterone and the ratio of kynurenine to tryptophan .
B. longum treatment significantly improved lung injury following infection and sepsis in mice. This probiotic also decreased lung inflammatory responses .
B. longum supplementation alleviated bone loss and increased bone formation parameters and bone mass density in ovariectomized rats .
Dietary B. longum significantly inhibited colon and liver and small intestinal tumors in male rats. In female rats, dietary supplementation also suppressed mammary carcinogenesis .
Freeze-dried cultures of B. longum significantly suppressed colon tumor incidence and tumor multiplicity and also reduced tumor volume in rats .
Various studies have investigated B. longum’s effect on the cellular level. These may or may not reflect the mechanisms of B. longum probiotics in the human body; however, they may help account for some of the observed effects of these probiotics in human studies.
- Decreased Th1-related cytokines (T-bet, IL-2, and IFN-γ) and Th17-related cytokines (IL-12p40, RORγt, IL-17A, IL-21, and IL-23), and increases Treg-related molecules (Foxp3, IL-10, and TGF-β) [29, 73, 40, 41, 3, 27].
- Decreased IL-1α , IL-1β [28, 35, 40], IL-6 [74, 38, 27] and IL-18 .
- Decreased TNF-α expression [28, 39, 38, 27].
- Increased IL-27 .
- Decreased CD80 and CD40 , CXCL1 [40, 27], CRP , iNOS and antimicrobial peptides Reg3b and Reg3g .
- Increased natural killer (NK) cell activity [4, 6, 9].
- Increased serum IgA  and decreased IgG2a productions .
- Increased IL-2, IL-12, and IL-18 .
- Decreased IL-6 [9, 10] and IL-8 .
- Decreased TNF-α .
- Both increased  and decreased IL-10 , and decreased [10, 13] and increased IFN-γ .
- Decreased IgE and improves the IgG2a/IgG1 ratio [48, 50, 75, 75, 76].
- Increased IgA .
- Increased Th1 cytokine and decreased Th2 cytokine production .
- Decreased IL-4 [75, 46] and IL-5  [a case where IL-5 was increased: 46].
- Increased IL-10 , IL-12 [76, 76] and TGF-β .
- Increased [45, 76] or decreased IFN-γ .
- Suppressed MDC and TARC .
- Increased CD4+CD25+Foxp3+ Treg cells .
- Decreased TNF-α [18, 20].
- Increased NFκB .
- Increased IL-10 .
- Reduced CD3⁺ T , CD4+ and CD4+/Foxp3+ cells  and increased CD8+ T .
- Increased MIP-1β .
B. longum is considered safe, but should be avoided in immunocompromised individuals, people with organ failure, and dysfunctional gut barrier, where probiotics may lead to infection. To avoid adverse effects, talk to your doctor about whether probiotics could be appropriate for you.