Bifidobacterium
Also called: bifidobacteria, Bifido
Bifidobacterium is a genus of bacteria that dominates the colon, especially in healthy infants and breastfed babies. They ferment dietary fibre into short-chain fatty acids, support immune function, and produce folate. Specific strains are well-studied probiotics for IBS, infant colic, and microbiome recovery after antibiotics.
What Bifidobacterium does
Bifidobacteria live mostly in the large intestine and ferment complex fibres that the small intestine can't digest. The end products are acetate, lactate, and indirectly butyrate (when other species cross-feed on bifido outputs). They train the immune system, lower colonic pH, and crowd out pathogens. They also produce folate, which is absorbed in the colon.
Strains with the strongest evidence
- Bifidobacterium infantis 35624 (sold as Align): improves bloating, gas and bowel habit in IBS in randomised trials.
- Bifidobacterium longum BB536: reduced influenza infection and fever in a trial in elderly adults; supports gut transit.
- Bifidobacterium breve M-16V: reduces eczema risk and severity in some infant trials.
- Bifidobacterium animalis subsp. lactis BB-12: improves bowel regularity, common in yoghurts.
- Bifidobacterium bifidum: foundational species, present in healthy breastfed infant guts.
Why they matter for infants
Healthy breastfed infants typically have a gut microbiome dominated by Bifidobacterium, often around 70 percent of bacteria on average. Human milk contains specific oligosaccharides (HMOs) that bifidobacteria are uniquely efficient at using, though some other gut bacteria can also consume them. This dominance trains the immune system, protects against pathogens, and influences long-term metabolic and allergy outcomes. Formula-fed and C-section infants have lower bifidobacteria, which is why some formulas now add HMOs and bifido strains directly.
Bifidobacterium vs Lactobacillus
- Niche: bifidobacteria mostly colon, lactobacilli mostly small intestine.
- Outputs: bifidobacteria produce acetate and lactate; lactobacilli mostly lactic acid.
- Oxygen: bifidobacteria are strict anaerobes (oxygen kills them); some lactobacilli tolerate oxygen.
- Both are common in probiotics; many products combine strains from both genera.
- Bifido strains are usually freeze-dried with stabilisers because they're so oxygen-sensitive.
How to encourage bifidobacteria
- Eat prebiotic fibres: inulin (onion, leek, garlic, asparagus, chicory), GOS (galacto-oligosaccharides, in legumes), and resistant starch (cooled cooked potato or rice).
- Eat polyphenols: berries, dark chocolate, green tea, red onion. Bifidobacteria thrive on these.
- Avoid frequent antibiotics. Bifidobacteria are particularly sensitive and can take months to recover.
- Breastfeed if possible. Human milk oligosaccharides selectively feed infant bifidobacteria.
- Targeted supplements (e.g. B. infantis 35624 for IBS, B. lactis BB-12 for regularity) when there's a specific reason.
Common questions
- Why do my Bifidobacterium levels drop with age?
- Bifidobacteria peak in infancy and decline through life. Lower fibre intake, more medications, slower gut transit, and immune ageing all contribute. Levels fall from being the dominant genus in infancy to a smaller fraction in adulthood (around 2 to 14 percent) and decline further in old age. Diet quality is the strongest factor you can control.
- Are Bifidobacterium probiotics safe in pregnancy?
- Generally yes. Several strains have been studied in pregnant and breastfeeding women without safety concerns. Bifidobacterium breve M-16V and Lactobacillus rhamnosus GG are most studied. Always check with your midwife if you have specific risk factors.
- Do I need both Bifidobacterium and Lactobacillus probiotics?
- Not usually. Many evidence-based products are single-strain. Multi-strain blends are popular but not necessarily better, sometimes worse, because strains can interfere with each other. Match the strain to your reason for taking it.
- Why does my probiotic say 'with HMOs'?
- HMOs (human milk oligosaccharides) are prebiotics that selectively feed bifidobacteria. Pairing them with a Bifidobacterium probiotic creates a synbiotic, the prebiotic feeds the probiotic. Useful in infants. Less clear evidence in adults but improving.
Sources
- Bifidobacteria and Their Role as Members of the Human Gut Microbiota, O'Callaghan & van Sinderen 2016 (Front Microbiol (PMID 27379055))
- Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with IBS (RCT), Whorwell et al 2006 (Am J Gastroenterol (PMID 16863564))
- Effects of Bifidobacterium longum BB536 on influenza infection and immunity in the elderly (RCT), Namba et al 2010 (Biosci Biotechnol Biochem (PMID 20460726))
- Exploring the Science behind Bifidobacterium breve M-16V in Infant Health (review of eczema/allergy trials), Wong et al 2019 (Nutrients (PMC6723912))
- Effect of Bifidobacterium animalis subsp. lactis BB-12 on defecation frequency (RCT), Eskesen et al 2015 (Br J Nutr (PMC4657032))
- Early development of infant gut microbiota in relation to breastfeeding and HMOs, 2023 (Front Nutr (PMC10034312))
- Gut Bifidobacteria Populations in Human Health and Aging, Arboleya et al 2016 (Front Microbiol (PMC4990546))
- Folate Production by Probiotic Bacteria, Rossi et al 2011 (Nutrients (PMC3257725))
- Probiotic Safety in Pregnancy: systematic review and meta-analysis of Lactobacillus, Bifidobacterium and Saccharomyces RCTs, Dugoua et al 2009 (J Obstet Gynaecol Can (PMID 19646321))
- ISAPP consensus statement on the definition and scope of synbiotics, Swanson et al 2020 (Nat Rev Gastroenterol Hepatol (PMC7581511))
- Genome of Bifidobacteria and Carbohydrate Metabolism (bifid shunt; acetate + lactate end products), Pokusaeva et al (PMC4682508)
- Bifidobacteria and Butyrate-Producing Colon Bacteria: cross-feeding to butyrate, Riviere et al 2016 (Front Microbiol (PMC4923077))
- Colonization Resistance in the Infant Gut: B. infantis reducing pH and preventing pathogen growth, 2020 (PMC7349288)