B. animalis (especially its subspecies B. lactis) is an important component of the healthy gut flora. It may promote GI well-being, especially in children, and some evidence suggests it may help the body prevent and fight off infections. What else could it do? Read on to find out.
What is Bifidobacterium animalis?
Bifidobacterium animalis is a gram-positive rod-shaped bacterium which can be found in the gut of most mammals, including humans. It is considered to be part of the healthy, beneficial gut flora .
B. lactis was previously considered to be a separate species but was shown to be a subspecies of B. animalis (hence B. animalis ssp. lactis) , and therefore it is addressed as such in this post. Note that most of the research mentioned below were carried out with this subspecies.
Potential Benefits of B. animalis
B. animalis probiotic supplements have not been approved by the FDA for medical use and 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.
Possibly Effective For
1) Gut Health
Diarrhea and Constipation
B. lactis milk formula administered to 50 children with acute diarrhea decreased the frequency, duration of diarrhea, and hospital stay .
B. animalis spp. lactis prevented acute diarrhea in 90 infants .
Treatment with B. animalis spp. lactis and inulin shortened the duration of acute diarrhea in 156 children. The benefits were most pronounced in cases of Rotavirus diarrhea .
B. animalis spp. lactis together with Streptococcus thermophilus reduced the frequency of antibiotic-associated diarrhea (AAD) in 80 infants .
Ingestion of fresh cheese enriched with B. animalis spp. lactis showed beneficial effects on constipation symptoms in women .
Fermented milk containing B. animalis spp. lactis had beneficial effects on stool frequency, defecation condition and stool consistency in 135 adult women with constipation .
B. animalis ssp. lactis increased Bifidobacteria and improved constipation in 17 human subjects .
B. animalis had a beneficial effect on discomfort, bloating and constipation in 274 constipation-predominant IBS patients .
B animalis spp. lactis significantly improved objectively measured abdominal girth and gastrointestinal transit, as well as reduced symptomatology in 34 IBS patients .
B. animalis spp. lactis and inulin significantly reduced treatment side effects and indirectly increased eradication rates by increasing patient compliance in 47 patients with symptomatic H. pylori infection .
B. animalis spp. lactis supplementation can increase Bifidobacteria and reduce Enterobacteriaceae and Clostridium in 324 infants .
4 weeks’ supplementation with B. animalis ssp. lactis resulted in a clinically relevant benefit on defecation frequency in 1248 healthy adults with abdominal discomfort .
B. animalis spp. lactis improved digestive comfort and GI symptoms in 371 healthy adults [15, 16].
Probiotic fermented milk containing B. animalis spp. lactis by healthy women may improve GI well-being and decrease the frequency of GI symptoms [17, 18, 19].
Gut Benefits in Animals
B. animalis ssp. lactis protected against NSAID-induced GI side effects in rats and may prevent more serious GI mucosal damage and/or enhance the recovery rate of the stomach mucosa .
B. animalis ssp. lactis improved colitis in mice [21, 22, 23].
B. animalis spp. lactis exhibited anti-inflammatory effects and reduces the incidence of diarrhea in rats with colitis .
B. animalis ssp. lactis protected barrier functions by restoring intestinal permeability, colonic goblet cell populations, and cytokine levels. It also restores the Th1/Th2 ratio by increasing the Th2 response in mice with chronic low-grade intestinal inflammation .
B. animalis ssp. lactis reduced days with cold/flu in 30 young healthy adults .
109 infants and children receiving B. animalis ssp. lactis experienced fewer respiratory tract infections [27, 28].
This probiotic did not, however, have an effect on the prevention of gastrointestinal and respiratory tract infections in daycare centers  and hospitalized children .
B. animalis ssp. lactis protected mice and rats from Toxoplasma gondii [31, 32] and nematode parasite infections .
B. animalis ssp. lactis protected mice against Salmonella infection and reduced infection severity [34, 35].
B. animalis ssp. lactis reduced the severity of infection due to E. coli in mice .
3) Infant Growth
B. animalis spp. lactis s’upplementation had a positive effect on growth in 594 vulnerable infants, such as infants born to mothers with HIV , and preterm infants .
Insufficient Evidence For
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of B. animalis for any of the below listed uses. Remember to speak with a doctor before taking B. animalis supplements and should never be used as a replacement for approved medical therapies.
Daily ingestion of milk containing B. animalis ssp. lactis significantly reduced the BMI, total cholesterol, low-density lipoprotein, and inflammatory markers in a study of 51 human patients with metabolic syndrome .
In the same study, B. animalis ssp. lactis significantly reduced BMI, total cholesterol, low-density lipoprotein and inflammatory cytokines .
The presence of B. animalis was also found to be negatively associated with BMI in two studies of a total of 378 human volunteers [41, 42].
B. animalis ssp. lactis reduced weight gain, fat mass and improved glucose tolerance in obese mice .
B. animalis ssp. lactis improved glycemia and reduced insulin levels in obese rats .
5) Anemia in Children
Milk with B. animalis ssp. lactis and prebiotic oligosaccharides reduced the risk of being anemic and iron deficient by 45% and increased weight gain by 0.13 kg/year in 624 children from 1-4 years of age .
B. animalis ssp. lactis augmented immunity in 26 healthy young women .
B. animalis spp. lactis supplementation in pregnancy influenced fetal immune parameters as well as immunomodulatory factors in breast milk in 71 women .
In a study of 172 otherwise healthy infants, B. animalis ssp. lactis mitigated the negative immune-related effects of not breastfeeding and cesarean delivery, possibly by augmenting the immune response, evidenced by increased anti-rotavirus- and anti-poliovirus-specific IgA .
B. animalis ssp. lactis stimulated the immune response to vaccination in 211 healthy adults .
B. animalis ssp. lactis significantly improved eczema symptoms in 27 infants .
B. animalis ssp. lactis improved immune parameters, decreased Th2 cytokines, and improved nasal symptoms in adult subjects suffering from seasonal allergic rhinitis .
B animalis skewed the Th1/Th2 balance towards Th1 in mice with allergies .
B. animalis ssp. lactis added to yogurt post-fermentation had anti-inflammatory properties in 30 healthy adults .
B. animalis ssp. lactis inhibited inflammation in elderly volunteers .
B. animalis ssp. lactis reduced inflammatory and T cells mediators, promoted regulatory T cells specific markers, reduced weight loss, and attenuated epithelial damage in mice with colitis .
B. animalis spp. lactis beneficially modified gut microbiota in 20 elderly volunteers, by increasing Bifidobacteria, Lactobacilli, and Enterococci and reducing Enterobacteria .
B. animalis spp. lactis enhanced natural immunity in 25 healthy elderly subjects .
B. animalis spp. lactis increased leukocyte phagocytic and NK cell tumor-cell-killing activity in the elderly. Increases in the proportions of total, helper (CD4(+)), and activated (CD25(+)) T lymphocytes and natural killer cells were also observed [58, 59, 60].
Animal Research (Lacking Evidence)
No clinical evidence supports the use of B. animalis 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. animalis ssp. lactis reduced weight gain and fat mass and improves glucose tolerance in diabetic mice .
B. animalis ssp. lactis decreased fasting insulin and blood glucose and significantly improved insulin tolerance in mice with noninsulin-dependent diabetes mellitus. This probiotic also improved diabetes-induced total cholesterol and triglyceride (TG) levels and increased the muscle glycogen content .
11) Antioxidant Activity
B. animalis culture supernatant, intact cells, and intracellular cell-free extracts all effectively scavenged free radicals and significantly enhanced the activities of antioxidative enzymes in mice .
12) Celiac Disease
Live B. animalis ssp. lactis bacteria directly counteracted the harmful effects exerted by celiac-toxic gluten (or, rather, a component of gluten called gliadin) on human intestinal cells .
13) Autoimmune Disease
In rats with experimental autoimmune encephalomyelitis, B. animalis significantly reduced the duration of clinical symptoms .
B. animalis ssp. lactis possesses the OXC gene, encoding oxalyl-coenzyme A (CoA) decarboxylase, a key enzyme in oxalate degradation .
B. animalis ssp. lactis significantly decreased urinary oxalate excretion in mice with hyperoxaluria by degrading dietary oxalate thus limiting its absorption across the intestine .
B. animalis ssp. lactis decreased the mean number and size of tumors in mice with colitis-associated cancer .
The synbiotic combination of carbohydrate ‘resistant starch‘ and B. animalis ssp. lactis protected against the development of colorectal cancer (CRC) in rats [66, 67].
These effects have not been observed in humans, and the degree to which gut flora or probiotics can affect the development of cancer in humans is unknown. Furthermore, people who are currently undergoing cancer treatment are often immunosuppressed, making them potentially vulnerable to adverse effects from probiotics.
Always talk to your doctor before starting a new probiotic, especially if you are being treated for cancer.
Mechanism of Effect
Researchers have been investigating the mechanisms by which B. animalis exerts its effects in animals and cells. In their findings, this probiotic has:
- Increased IgA [35, 47, 48, 36, 46], IgG, IgG1, and IgG3 .
- Elevated NK-cell cytotoxicity .
- Decreased TNF-α [40, 24, 54].
- Increased TGF-β1 .
- Increased IFN-α  and IFN-γ .
- Increased IL-2  and IL-10 [35, 25].
- Increased IL-4 and IL-5 in low-grade inflammation .
- Decreased IL-5 and IL-13 in allergy .
- Both decreased  and increased  IL-6.
- Decreased iNOS, COX-2 , PCK1 and G6PC .
- Increased PP-1, GLUT4  and FOXP3 .
- Induced CD19 lymphocyte proliferation in parasite infection .
- Mostly decreased NF-κB [69, 23] [a study where it was increased: 68].
B. animalis is safe and well tolerated in infants, adults and elderly. Probiotics are generally considered safe but should be avoided in patients with organ failure, immunocompromised status, and dysfunctional gut barrier mechanisms. To avoid adverse effects and unexpected interactions, talk to your doctor before starting any new probiotics.