Fermentation yeasts

Live micro-organisms

The yeasts of live fermented drinks — kefir, kombucha, beers on lees.

Nutritional yeast is inactivated: it provides beta-glucans, not live yeasts.

Effects and benefits

The yeasts of live fermented drinks make B vitamins during fermentation. Kefir and kombucha were among the fermented foods that, in the Stanford trial, increased microbiota diversity.

In kefir and kombucha, yeasts and bacteria live in a colony, as grains or a “mother”, where each feeds the other: yeasts make alcohol and carbon dioxide, bacteria turn the alcohol into acids. The result is a drink low in sugar, tart, fizzy, rich in B vitamins.

In the Stanford trial, kefir and kombucha were part of the fermented-food diet that increased microbiota diversity and lowered markers of inflammation (Wastyk et al., 2021).

Kefir is often well tolerated by people who digest lactose poorly: its cultures have already consumed part of it (Hertzler and Clancy, 2003).

Sources: Wastyk et al., Cell, 2021 · Hertzler and Clancy, J Am Diet Assoc, 2003

Where to find it (7)

• Kefir
• Kumis
• Tepache
• Unfiltered beer on lees
• Unfiltered cider
• Unpasteurized kombucha
• Water kefir

Also, in smaller amounts (3)

• Frênette (ash leaf drink)
• Palm wine
• Tej