PubMed · 2026-05-22
Drinking a daily glass of water kefir — a plant-based fermented beverage — for two weeks measurably shifted gut bacteria in healthy adults toward species linked to digestive health, including a 21.6% rise in Bacteroidetes and increases in beneficial genera like Bifidobacterium.
Bacteroidetes increased 21.6% and Actinobacteria 14.8%, while Firmicutes dropped 6.5% after just 14 days of 200 mL daily water kefir consumption.
Beneficial genera Bifidobacterium and Prevotella both increased, and the overall community structure shifted significantly (β-diversity, p = 0.025), indicating a real ecological change rather than random noise.
Short-chain fatty acid-producing species — Blautia spp. and Roseburia faecis — increased, pointing toward potential metabolic benefits, though 66% of participants noticed no change in digestive symptoms.