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Bifidobacterium longum

Supplement probiotic gutbrain & mood
Aka: B. longum, BB536
Brands seen in Singapore: California Gold Nutrition, 21st Century, Garden of Life, NOW Foods, Lemme
Third-party tested: Garden of Life, Lemme certify other products with NSF Certified for Sport, but nothing for bifidobacterium longum.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Constipation in older adults · IBS pain, strain-specific
When to take
Daily
Take with
Water · cfu at end of shelf life is the number that counts
Studied for
The bb536 constipation trial ran 4 weeks
Pros & cons
Pros
  • Bb536 5x10^10 cfu/day raised stool frequency
  • B. longum 35624 met the bar in a 2026 IBS review
  • Unlikely to harm healthy people; gas is the usual
Cons
  • Bb536 missed its primary endpoint (p=0.074)
  • Cognitive data: one 22-person single-blind trial
  • A perinatal mood RCT found no difference vs placebo
Sources
  1. NIH NCCIH — Probiotics: Usefulness and Safety — Constipation (2017 evaluation of 9 studies) · read 2026-08-27
    what it says
    “A 2017 evaluation of 9 studies (778 participants) of probiotics for constipation in elderly people indicated that probiotics produced a small but meaningful benefit. The type of bacteria most often tested was Bifidobacterium longum”
  2. NIH ODS — Probiotics Fact Sheet for Health Professionals — Irritable bowel syndrome (meta-analysis of 10 RCTs, 877 adults) · read 2026-08-27
    what it says
    “a meta-analysis of 10 RCTs … 877 adults … probiotics that contained Bifidobacterium breve, Bifidobacterium longum, or Lactobacillus acidophilus species had lower pain scores than those who received placebo”
  3. NIH ODS — Probiotics Fact Sheet for Health Professionals — Identification / Mechanisms of action (read via archive.org; ods.od.nih.gov is Cloudflare-blocked) · read 2026-08-27
    what it says
    “Because the effects of probiotics can be specific to certain probiotic strains, recommendations for their use in the clinic need to be strain-specific … Probiotics may transiently colonize the human gut mucosa in highly individualized patterns”
  4. NIH ODS — Probiotics Fact Sheet for Health Professionals — Dietary Supplements (CFU labelling, shelf life) · read 2026-08-27
    what it says
    “Many probiotic supplements contain 1 to 10 billion CFU per dose, but some products contain 50 billion CFU or more. However, products with higher CFU counts are not necessarily more effective”
  5. NIH ODS — Probiotics Fact Sheet for Health Professionals — Dietary Supplements (viability at end of shelf life) · read 2026-08-27
    what it says
    “probiotics must be consumed alive … users should look for products labeled with the number of CFU at the end of the product's shelf life, not at the time of manufacture”
  6. NIH ODS — Probiotics Fact Sheet for Health Professionals — Safety Considerations · read 2026-08-27
    what it says
    “Probiotics are unlikely to cause harm in healthy people, and side effects are usually minor … linked to a few cases of bacteremia, fungemia, and infections … most of these cases involved individuals who were severely ill or immunocompromised”
  7. NIH NCCIH — Probiotics: Usefulness and Safety — Can probiotics be harmful? / FDA 2023 preterm warning · read 2026-08-27
    what it says
    “The risk of harmful effects from probiotics is greater in people with severe illnesses or compromised immune systems … the FDA warned health care providers that premature infants who are given probiotics are at risk of severe, potentially fatal infections”
  8. Strain-Specific Systematic Review with Meta-Analysis of Probiotics Efficacy in the Treatment of Irritable Bowel Syndrome (Maslennikov et al., J Clin Med 2026; 32 RCTs, 10 strains) · read 2026-08-27
    what it says
    “Meta-analyses demonstrated the efficacy of Bifidobacterium longum (formerly Bifidobacterium infantis) 35624 … and Bacillus coagulans Unique IS2 (MTCC 5260) … did not demonstrate the efficacy of Escherichia coli Nissle 1917, Lactobacillus gasseri BNR17, or Lactobacillus casei Shirota”
  9. Usefulness of Bifidobacterium longum BB536 in Elderly Individuals With Chronic Constipation: A Randomized Controlled Trial (Am J Gastroenterol 2023; n=79) · read 2026-08-27
    what it says
    “B. longum BB536, 5 x 10^10 colony-forming unit … once daily for up to 4 weeks … The primary end point was not significant (P = 0.074) … significant difference … on the stool frequency (P = 0.008)”
  10. Effect of Bifidobacterium longum on cognition and microbiota in post-stroke patients: a single-blinded, controlled trial (Int J Med Sci 2026; n=22) · read 2026-08-27
    what it says
    “Supplementation of Bifidobacterium longum OLP-01 at a dose of 2 x 10^10 CFU daily for 12 weeks improved cognitive function and changes gut microbiota, but did not alter physical performance in post-stroke patients”
  11. The impact of ingestion of Bifidobacterium longum NCC3001 on perinatal anxiety and depressive symptoms: a randomized controlled trial (Sci Rep 2025; N=184) · read 2026-08-27
    what it says
    “Contrary to our hypothesis, we did not observe any differences between groups in mood outcomes … BL NCC3001 was not detected after the intervention in all of the intervention group participants”
  12. HSA — Health Supplements Guidelines (January 2026), s3.1 working definition; Table 2 microbial limits; Tables 4–5 cover vitamins and minerals only · read 2026-08-27
    what it says
    “Vitamins, minerals, amino acids, fatty acids, enzymes, probiotics and other bioactive substances … The above limits for total aerobic microbial count, and yeast and mould may not be applicable to certain products such as probiotics”
  13. HSA — Guidelines on Prohibited and Restricted Ingredients in HS and TM, GL-CHPB-1-012 Rev. 001 (October 2025), clause 1.3 + Annex A/B · read 2026-08-27
    what it says
    “to highlight the substances of concern when used in HS and TM and is not meant to be an exhaustive list [no probiotic, Lactobacillus, Bifidobacterium, Bacillus or Akkermansia row appears in Annex A or B]”
  14. iHerb Singapore — 'Probiotic Supplements for Gut Health' category page, default order (page now Cloudflare-blocked; row carried over from the KB's probiotics entry, same access date) · read 2026-08-27
    what it says
    “California Gold Nutrition, LactoBif® 30 Probiotics … 21st Century, Cranberry Plus Probiotic … Garden of Life, Dr. Formulated Probiotics, Once Daily Women's, 50 Billion … NOW Foods, Probiotic-10™ … Lemme, Purr, Vaginal Probiotic Gummies”
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Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.