Must be alive
Dead cells and metabolites are different products (sometimes called postbiotics). Heat-killed is not the 2001 definition.
The FAO/WHO 2001 working definition — live microorganisms that confer a health benefit when administered in adequate amounts — still frames labels. A yoghurt culture is not automatically a probiotic until a strain and a dose have evidence.
Effects are strain-specific. Lactobacillus rhamnosus GG is not interchangeable with a random 'lactobacillus' on a gummy.
Traits
Strain, not genus
Evidence attaches to a strain code. 'Bifido' on a label is a phone book, not a trial.
Adequate amount
Labels shout billions of CFU. Survival through the shelf and the stomach is the unprinted chapter.
Not the whole microbiome
A capsule is a few guests. The gut already hosts thousands of lineages.
Food or capsule
Traditional yoghurts, some kimchi-adjacent products and pills occupy different evidence piles.
Debate is normal
Some indications have trials; many labels do not. Scepticism is part of the science.
This page is education, not a recommendation to start, stop or replace a medicine.
Keep exploring
More in Beneficial allies
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