Homemade kefir is a simple, solid way to bring microbial diversity into your diet — but the '30 different microorganisms' figure varies a lot by grain source, and the measured clinical effect stays modest.

noli's read

Kefir is genuinely one of the richer fermented foods microbially: recent reviews catalog dozens of species of lactic acid bacteria, acetic acid bacteria, and yeasts depending on the origin of the grains used — so the '30 microorganisms' figure is a plausible ballpark rather than an exaggeration, even though it varies a lot from one batch of grains to another (one analysis found a single species dominating 87% of a Korean grain sample). Recent controlled trials show that drinking kefir daily measurably shifts certain short-chain-fatty-acid-producing bacteria (Blautia, Bifidobacterium) in healthy adults, which supports a real effect on the microbiome. That effect stays modest and inconsistent across studies, though: a 28-day trial comparing kefir, milk, and yogurt only detected a clear taxonomic change in 4 of 10 participants in the kefir group. So the video's advice — homemade kefir as a fermented food worth trying regularly — holds up in principle, without promising a microbiome overhaul for everyone.

the sources

1. 1Wastyk HC, Fragiadakis GK, Perelman D, et al. 2021
2. 2Liu RT, Walsh RFL, Sheehan AE 2019