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Understanding the Gut Bacteria Bifidobacterium longum: A Comprehensive Guide to Health Benefits and Testing Patient Levels

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Understanding the Gut Bacteria Bifidobacterium longum: A Comprehensive Guide to Health Benefits and Testing Patient Levels

Bifidobacterium longum (B. longum) is one of the first species of probiotic bacteria to colonize the human intestinal microbiome after birth. The microbiome houses trillions of bacterial cells, which perform many physiological functions pertaining to the maintenance of a healthy gastrointestinal tract, immune function, energy regulation, and nutrient synthesis. This article will discuss B. longum's role in human health, factors influencing its abundance within the gut, and things you can do to support it. (4)


What Is Bifidobacterium longum?

Bifidobacterium longum is a Gram-positive probiotic bacteria found in the human intestinal microbiome and the intestines of most animals and insects. It was first isolated over one hundred years ago from human feces and quickly identified as a healthy microfloral organism due to its dominance in breastfed infants. (1)

There are three subspecies of B. longum: longum, infantis, and suis. Because of its ability to withstand and resist the acidic nature of the upper digestive tract, B. longum is a dominant species within the intestinal microbiome. This, along with the numerous studies demonstrating its health benefits extending beyond the gastrointestinal tract, makes B. longum a popular probiotic choice among healthcare providers. (1, 2)

What Are the Health Benefits of Bifidobacterium longum?

B. longum plays an essential role in maintaining gut health. It, along with other resident bacteria, prevents pathogenic intestinal infections by binding receptor sites on intestinal epithelial cells, effectively crowding out harmful bacteria and secreting chemicals called bacteriocins, which inhibit the growth of and kill pathogenic bugs.

B. longum is also one of the gut's predominant bacterial producers of lactate and acetate. These metabolic byproducts lower the intestinal pH, making it more acidic, which enables good bacteria to thrive while simultaneously preventing the overgrowth of harmful microorganisms. (3)

Oral supplementation of B. longum probiotics has demonstrated improvements in functional constipation, relieves inflammation and symptoms associated with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS), prevents necrotizing enterocolitis in infants, induces lactose digestion in patients with lactose intolerance, and improves diarrhea. (4)

Studies consistently show positive immunomodulatory effects of B. longum strain BB536 consumption on the immune system. As such, oral administration of this probiotic strain has been applied to and shown effective in preventing tumor growth; reducing systemic inflammation (including in patients with chronic fatigue syndrome and psoriasis); alleviating allergies; and stimulating immune responses to prevent viral respiratory infections. (5-8)

The microbiota-gut-brain axis describes the communication pathways between the intestinal microbiota, microbial metabolites, and the nervous system. B. longum is intimately connected with the nervous system and influences mood, cognition, and brain health by producing gamma amino butyric acid (GABA), short-chain fatty acids (SCFAs), and regulating serotonin synthesis by enterochromaffin cells in the intestines. B. longum 1714™ has been shown to modulate cortisol output, activate brain coping centers in response to stress, and reduce mental fatigue. Studies have also demonstrated improved depression scores, sleep quality, and cognitive function with various strains of B. longum probiotics. (4)

What Causes Low Levels of Bifidobacterium longum?

B. longum levels are highest at birth and naturally decline with age. However, modifiable factors increase the risk of having a lower microfloral abundance of B. longum. Various diseases, like obesity, diabetes, and allergies, have been associated with lower numbers of bifidobacteria. Cigarette smoking is also associated with decreased Bifidobacterium levels. (9)

Diet is also a strong influencer of microbiome composition. A Western diet, characterized by low fiber and high animal protein intake, is associated with low Bifidobacterium. Similarly, because of its low fiber content, the low FODMAP diet has been associated with lower levels of B. longum. (10)

What Causes High Levels of Bifidobacterium longum?

What we eat can also positively impact B. longum levels in the gut microbiome. Long-term compliance with the Mediterranean diet, emphasizing a wide variety of vegetables, fruits, nuts and seeds, and healthy fats, increases B. longum. (10)

Bifidobacteria have about 20% higher relative abundances in babies that are breastfed versus those that are formula-fed.

Physical activity can also promote Bifidobacterium growth. One study found that women who exercised at least three hours weekly had high fecal Bifidobacterium spp. than women who did not.

How to Test Bifidobacterium longum Levels

Comprehensive stool testing is a functional medicine tool that provides in-depth insight into the health and function of the digestive tract, as well as a detailed analysis of the diversity and abundance of the gut microbiome. There are many stool tests to choose from, and most will quantify the growth of Bifidobacterium spp. within a patient's fecal sample. The Gut Zoomer 3.0 Complete by Vibrant Wellness may be a preferred test for those specifically interested in testing B. longum levels. This test, in addition to providing a fecal measurement of Bifidobacterium spp., measures B. longum ssp. longum and infantis.

Foods That Help Increase Bifidobacterium longum Levels

Adding high-fiber, prebiotic, and probiotic foods into the diet will help increase B. longum levels in the gut. Fruits, vegetables, beans, and whole grains are excellent soluble and insoluble fiber sources. Onions, garlic, and soybeans are examples of prebiotic-containing foods. Fermented foods, such as live-culture yogurt, tempeh, kimchi, sauerkraut, and pickled vegetables, are probiotic foods that can be eaten as an alternative to probiotic supplements. (10)

Consumption of whey and pea proteins has increased commensal gut Bifidobacterium levels while decreasing pathogenic bacterial species. (10)

Polyphenols are naturally occurring antioxidant plant compounds that increase Bifidobacterium levels in the gut. Polyphenols are found in foods such as, but not limited to, dark chocolate, blueberries, coffee, green tea, and red wine. (10)

Supplements That Increase Bifidobacterium longum Levels

Supplements can work alongside healthy dietary choices to restore B. longum. There are many probiotics, nutritional supplements containing live bacterial cultures, containing Bifidobacterium spp., including B. longum.

Probiotics containing, or taken alongside, prebiotics can support the beneficial gut microbiome by providing fuel for the good microbes. Prebiotic supplements often have some combination of inulin, fructooligosaccharides (FOS), galactooligosaccharides (GOS), pectin, and guar gum.

How to Make Sure You Are Getting High-Quality Bifidobacterium longum Supplements

High-quality probiotic supplements from a trusted brand are essential to ensure you receive live, active bacterial cultures free of unsafe ingredients. In one study, five of 19 probiotics had lower bacterial counts and other types of probiotics than what was listed on their nutritional labels. (11)

When choosing a probiotic supplement, look for one manufactured by a company that follows cGMPs (regulatory practices that ensure safety in supplement production and packaging techniques) and is contracted with a third-party certifier that tests the product for nutritional label accuracy. (12)

Because probiotic efficacy is strain, dosage, and disease-dependent, other important details to consider when purchasing probiotic supplements are colony-forming units (CFU), expiration date, and bottle storage. (13)



As research continues to prove the impact of the gut microbiome on human health, it is clear that early colonization of the gastrointestinal tract with Bifidobacterium longum is important for disease prevention. Low levels of B. longum are associated with disease pathology, and supplementation with this probiotic bug results in improved health markers and symptom resolution. Healthy lifestyle choices are foundational in maintaining a healthy population of Bifidobacterium, and probiotic/prebiotic supplements can be added on board, as necessary, to support the symbiotic relationship between humans and this probiotic microorganism.

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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Lab Tests in This Article


1. Proteomes - Bifidobacterium longum (strain DJO10A). UniProt.

2. Quigley, E.M.M. (2017). Bifidobacterium longum. In Elsevier eBooks (pp. 139–141).

3. Van Der Meulen, R., Adriany, T., Verbrugghe, K., et al. (2006). Kinetic Analysis of Bifidobacterial Metabolism Reveals a Minor Role for Succinic Acid in the Regeneration of NAD+ through Its Growth-Associated Production. Applied and Environmental Microbiology, 72(8), 5204–5210.

4. Mills, S., Yang, B., Smith, G.J., et al. (2023). Efficacy of Bifidobacterium longum alone or in multi-strain probiotic formulations during early life and beyond. Gut Microbes, 15(1).

5. Malaguarnera, M., Vacante, M., Antic, T., et al. (2012). Bifidobacterium longum with Fructo-Oligosaccharides in Patients with Non Alcoholic Steatohepatitis. Digestive Diseases and Sciences, 57(2), 545–553.

6. Groeger, D., O'Mahony, L., Murphy, E., et al. (2013). Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut. Gut Microbes, 4(4), 325–339.

7. Puccio, G., Cajozzo, C., Meli, F., et al. (2007). Clinical evaluation of a new starter formula for infants containing live Bifidobacterium longum BL999 and prebiotics. Nutrition, 23(1), 1–8.

8. Wong, C.B., Odamaki, T., & Xiao, J. (2019). Beneficial effects of Bifidobacterium longum subsp. longum BB536 on human health: Modulation of gut microbiome as the principal action. Journal of Functional Foods, 54, 506–519.

9. Arboleya, S., Watkins, C., Stanton, C., et al. (2016). Gut Bifidobacteria Populations in Human Health and Aging. Frontiers in Microbiology, 7.

10. Singh, R., Chang, H., Yan, D., et al. (2017). Influence of diet on the gut microbiome and implications for human health. Journal of Translational Medicine, 15(1).

11. Moore, W. (2022, August 7). Which Probiotic is Right for You? WebMD.

12. Cloyd, J. (2023, April 28). What is the Difference Between Medical-Grade Supplements and Over-the-Counter Supplements? Rupa Health.

13. How To Pick the Best Probiotic. (2022, October 13). Cleveland Clinic.

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