Health & Well-Being A-Z

Bifidobacterium longum


Bifidobacterium longum (B. longum) is a type of probiotic ("good" bacteria) that lives in the intestines. It produces lactic and acetic acid in the gut.

"Good" bacteria such as B. longum can help break down food, absorb nutrients, and fight off "bad" organisms that might cause diseases. Two subspecies of this bacteria, B. longum subsp. infantis and B. longum subsp. longum, are found in the human gut and used in probiotic supplements.

People use B. longum for eczema, athletic performance, constipation, colic, and many other purposes, but there is no good scientific evidence to support these uses. There is also no good evidence to support using B. longum for COVID-19.

Don't confuse B. longum with other probiotics, or with fermented food products such as fermented milk, kefir, or yogurt. These are not the same.

Is It Effective?


There is interest in using B. longum for a number of purposes, but there isn't enough reliable information to say whether it might be helpful.

Is it Safe?


When taken by mouth: B. longum is likely safe. It's been used safely alone and together with other probiotics for up to one year. Some people might experience gas and bloating from probiotics, but B. longum seems to be well-tolerated.

Special Precautions & Warnings:

Pregnancy and breast-feeding: B. longum is possibly safe when taken by mouth. It's been used safely throughout pregnancy, and also for 2 months after delivery while breast-feeding.

Children: B. longum is likely safe for most children when taken by mouth for up to 4 months. However, there isn't enough reliable information to know if B. longum is safe for very small premature infants. There have been cases of blood infection with B. longum in critically ill babies.

Weakened immune system: Some probiotics have caused blood infections in a small number of people with weakened immune systems. If you have a weakened immune system, talk with your healthcare provider before taking B. longum.

Drug interactions

Antibiotic drugs

Interaction Rating=Moderate Be cautious with this combination.

B. longum is a type of friendly bacteria. Antibiotics are used to reduce harmful bacteria in the body. Taking antibiotics along with B. longum might reduce the effects of B. longum. To avoid this interaction, take B. longum products at least two hours before or after antibiotics.

Herb interactions

There are no known interactions with herbs and supplements.

Food interactions

There are no known interactions with foods.


In adults, B. longum has most often been taken by mouth alone or together with other probiotics in doses of up to 20 billion colony-forming units (CFUs) daily for up to 8 weeks. In children, B. longum has most often been taken by mouth alone or together with other probiotics. Speak with a healthcare provider to find out what dose might be best for a specific condition.

Other names

B. Infantis, B. Longum, Bifido Bacterium Longum, Bifidobacterium Infantis, Bifidobacterium Longum subsp. Infantis, Bifidobacterium Longum subsp. Longum, Bifidus Infantis, Bifidus Longum, Probiotic, Probiotique.


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