Kefir for Lactose Intolerance

Research suggests that kefir may help reduce symptoms of lactose intolerance, primarily by improving lactose digestion through the activity of bacteria present in the fermented drink. The strongest direct evidence comes from a small randomized controlled trial (n=15) showing that plain kefir significantly reduced breath hydrogen levels — a marker of undigested lactose — and reduced flatulence severity by roughly 54–71% compared to regular milk, with results comparable to yogurt; several reviews from 2011, 2013, and 2023 also cite reduced lactose intolerance symptoms as a consistently reported benefit of kefir consumption. A 2022 storage study of sheep's milk kefir found it broke down approximately 52% of lactose over 21 days of refrigeration, suggesting meaningful lactose reduction even in the product itself. Taken together, the body of evidence is directionally supportive but remains limited by the small scale and low volume of controlled human trials, and several of the included sources are review articles or animal and cell studies that do not directly test kefir's effect on lactose intolerance in humans, meaning more rigorous clinical research would be needed before strong conclusions can be drawn.