“White gold”: The ancient food that may help restore gut flora

Kefir, a fermented drink with roots in the Caucasus, is attracting renewed scientific attention for its possible effects on the gut. Its white, gelatinous grains contain a symbiotic community of lactic-acid bacteria and yeasts, with some cultures containing up to 60 different strains.

When the grains ferment sugars, they produce lactic acid, ethanol, carbon dioxide and bioactive compounds that change the original liquid. The result is a drink rich in living microorganisms, which researchers have linked to digestive, immune and metabolic processes.

“The concept is a community of bacteria and yeasts that live in symbiosis, meaning they benefit from living together,” said César Casavola, president of Argentina’s Society of Nutrition Physicians.

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The concept is a community of bacteria and yeasts that live in symbiosis, meaning they benefit from living together.

Kefir’s history is traced to the Caucasus, where farmers made a drink called ayrag by leaving milk in unwashed goatskin containers. A white film formed inside the containers and produced a new drink with a distinctive taste and a longer shelf life. The word kefir comes from Turkish and means “to feel well.”

Research, much of it conducted in laboratory or animal studies, has associated kefir with indicators including greater microbial diversity. Its bacteria and yeasts can produce organic acids, enzymes and kefiran, a polysaccharide that forms part of the kefir matrix. Casavola said these compounds can lower intestinal pH, inhibit opportunistic bacteria and act as prebiotics. Both milk and water kefir may help restore microbial balance after antibiotic treatment, although human evidence remains limited and inconsistent.

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To feel well.