What it is
Probiotics are live bacteria or yeasts. The NIH identifies them by genus, species and strain (for example Lacticaseibacillus rhamnosus GG, known as LGG) and specifies that their effects can be specific to certain strains. People buy them mostly for digestion, during or after antibiotics, and for immunity.
What the label does not say
- The effect belongs to the strain, not the genus: the NIH writes that recommendations must be strain-specific. A bottle that shows only "Lactobacillus acidophilus" without a strain code (GG, BB-12, La1) says neither which bacterium it contains nor which data attach to it.
- The CFUs "at time of manufacture" are not the CFUs at expiry. The NIH advises looking for the number declared at the end of shelf life; Health Canada requires that at least 80% of the declared quantity still be present up to expiry, in CFUs, and refuses grams, because the weight includes dead cells.
- The NIH relays the recommendation to check on the label whether the product goes in the refrigerator or at room temperature: the declared CFU count assumes those conditions are met.
- "Microbiome balance" has no data in healthy people: the NIH finds no formal recommendation for or against in healthy people, and the AGA (2020) recommends probiotics in irritable bowel, Crohn's disease and ulcerative colitis only within a clinical trial.
The forms on the shelf
- Capsules, sachets or drops of named strains: the NIH indicates that many products contain 1 to 10 billion CFUs per dose, some 50 billion and more, and that a higher count is not necessarily more effective.
- Saccharomyces boulardii: a yeast, not a bacterium. Antibiotics do not destroy it, but the Health Canada monograph asks you to space it 2 to 3 hours from antifungals.
Published reference values
- Antibiotic-associated diarrhea: risk reduction of about 51% in meta-analysis according to the NIH; in children, the 2019 Cochrane review (33 trials, 6,352 children) reports 8% versus 19%, one case prevented for every 9 children, with LGG or S. boulardii at 5 to 40 billion CFUs per day.
- Health Canada ties the claim on this diarrhea to 10 to 20 billion CFUs per day of LGG or 10 to 30 billion of S. boulardii; the general claim "helps to support intestinal health" requires only 10 million CFUs, a thousand times less.
- Irritable bowel: a meta-analysis of 23 trials (2,575 patients) cited by the NIH reports a 21% lower risk of symptoms persisting, depending on the strain. NICE advises trying for at least 4 weeks, at the manufacturer's dose, while monitoring the effect.
- No recommended intake or upper limit: they are not nutrients.
When
With an antibiotic, Health Canada asks you to take bacterial strains at least 2 to 3 hours before or after the antibiotic; ESPGHAN (2023, cited by the NIH) advises starting at the same time as the antibiotic, at 5 billion CFUs or more per day of LGG or S. boulardii.
Keep apart from
- Antibiotics: at least 2 to 3 hours apart for bacterial strains (Health Canada).
- Antifungals: at least 2 to 3 hours apart for yeasts such as S. boulardii (Health Canada).
To mention to a professional
- Immune deficiency (AIDS, lymphoma, prolonged corticosteroid therapy), a contraindication according to Health Canada; serious illness, central venous catheter, intensive care (cases of bacteremia and fungemia reported by the NIH); prematurity (FDA warning in 2023); fever, vomiting, bloody diarrhea or intense abdominal pain; pregnancy and breastfeeding: check with a health care professional.
From the plate first
Yogurt (Lactobacillus bulgaricus, Streptococcus thermophilus, sometimes Bifidobacterium) is the fermented food with defined strains according to the NIH; kimchi, sauerkraut, kombucha, miso and cheeses contain live cultures, not typically documented probiotic strains.
Sources
- NIH Office of Dietary Supplements, Probiotics (Health Professional)
- NCCIH, Probiotics: What You Need To Know
- Health Canada, natural health product monograph, Probiotics
- Cochrane, Guo et al., Probiotics for the prevention of pediatric antibiotic-associated diarrhea (2019)
- NICE, Irritable bowel syndrome in adults: diagnosis and management (CG61), recommendations
- American Gastroenterological Association, Clinical practice guideline on the role of probiotics in the management of gastrointestinal disorders (2020)
Educational information, drawn from the sources above. It does not replace the advice of a health professional, who remains the reference for your situation, your medications, pregnancy or breastfeeding.