What actually counts as a fermented food? The expert consensus

What does the research say?

An international expert panel agreed a clear definition: fermented foods are made through the deliberate growth of microbes. Importantly, not all fermented foods contain live microbes when you eat them. Bread, most beer and wine, and pasteurised sauerkraut are fermented but no longer ‘live’.

The science

The panel defined fermented foods as ‘foods made through desired microbial growth and enzymatic conversions of food components’. They distinguished these from probiotics, which must contain defined live microbes shown to have a health benefit.

Fermentation can change foods in useful ways: producing vitamins such as K2, reducing lactose, and creating flavour compounds. The strongest human evidence so far is for fermented dairy such as yoghurt, with much less trial evidence for other fermented foods.

Key findings

A consistent scientific definition of fermented foods.
Baking, pasteurising and filtering remove live microbes from many fermented foods.
Fermented foods shouldn’t be called ‘probiotic’ unless specific strains and benefits are proven.
More well-designed human trials are needed.

Limitations

This is an expert review, not a new study.
Evidence is uneven: most comes from fermented dairy.
Health effects can’t be assumed to be the same across different fermented foods.

References

Marco ML, Sanders ME, Gänzle M, et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol. 2021;18(3):196–208. doi.org/10.1038/s41575-020-00390-5