Bifidobacterium longum is a beneficial probiotic bacterium commonly found in the human gut. It is a Gram-positive, rod-shaped bacterium, and an early colonizer of an infant’s gastrointestinal tract. This microorganism helps maintain the balance of the gut microbiota, a collection of trillions of bacterial cells performing functions related to digestion, immune function, and nutrient synthesis.
Understanding B. longum’s Function
Bifidobacterium longum contributes to gut health by producing short-chain fatty acids, lactic and acetic acid. These acids help lower the pH of the intestine, creating an environment that inhibits the growth of harmful bacteria. This process supports food breakdown and nutrient absorption.
Beyond acid production, B. longum influences gut barrier function and modulates the immune response. It protects intestinal epithelial cells by reducing oxidative stress and downregulating inflammatory cytokines. The bacterium also produces active metabolites that interact with various bodily systems, including digestive, endocrine, cardiovascular, immune, and nervous systems.
Key Subspecies
Bifidobacterium longum has three subspecies, two relevant to human health: B. longum subsp. longum and B. longum subsp. infantis. While genetically very similar, they exhibit distinct characteristics and are found in different populations. B. longum subsp. infantis is common in breastfed infants, specializing in human milk oligosaccharides (HMOs) as a food source.
B. longum subsp. longum is more prevalent in adults and specializes in plant-derived carbohydrates. Both subspecies contribute to immune benefits, but B. longum subsp. infantis is particularly beneficial for developing gut microbiomes in early life, while B. longum subsp. longum may offer relief for conditions like constipation. Due to their distinct roles and prevalence, these subspecies are often listed separately in probiotic products.
Common Uses and Scientific Support
Bifidobacterium longum is widely used in probiotic supplements and has been explored for various health conditions. Some research suggests a potential role in managing eczema, particularly in infants. Studies indicate that certain B. longum strains may promote the differentiation of skin cells and modulate immune responses, potentially reducing eczema risk. However, the certainty of evidence for preventing eczema in infants is considered low, and long-term effects may be limited.
A study on collegiate female swimmers found that B. longum supplementation did not directly impact exercise performance or immune function. It did, however, show alterations in cognitive outlook, with the probiotic group reporting higher sport recovery. This suggests a potential indirect effect on performance through improved cognitive stress-recovery.
For constipation, B. longum has shown promise in animal studies by regulating the intestinal barrier, increasing acetate levels, and improving intestinal motility. While promising, more human trials are needed to confirm these effects. The use of B. longum for colic is also a common application, but the scientific evidence for its effectiveness is not yet conclusive.
Safety and Potential Side Effects
Bifidobacterium longum is generally considered safe for consumption. It has been safely used alone and in combination with other probiotics for up to a year. For pregnant and breastfeeding individuals, B. longum is possibly safe when taken orally, with safe usage reported throughout pregnancy and for two months postpartum.
While generally well-tolerated, some individuals may experience mild digestive side effects when starting probiotic supplementation. These can include temporary increases in gas and bloating. These symptoms usually subside within a few days to a few weeks as the body adjusts to the new bacteria. In rare cases, particularly for individuals with severely weakened immune systems or very small premature infants, there have been reports of blood infections.