Bifidobacteria are a genus of probiotic bacteria commonly found in the human gut and frequently used in fermented dairy products and supplements. Their use in supporting or treating lactose intolerance is scientifically supported, although the overall strength of evidence is moderate (rated 3 out of 5). Several clinical studies have shown that certain strains of Bifidobacteria possess β-galactosidase activity—the enzyme responsible for breaking down lactose into glucose and galactose, thus aiding digestion in lactose-intolerant individuals. When Bifidobacteria are consumed, either through fortified yogurts or supplements, they can help improve lactose digestion and reduce symptoms such as bloating, diarrhea, and abdominal pain.

Notably, randomized controlled trials have demonstrated that fermented dairy products containing Bifidobacteria are better tolerated by lactose-intolerant individuals compared to unfermented milk. However, the efficacy appears to be strain-dependent and may vary based on the individual's existing gut microbiota and the delivery format of the probiotic. Meta-analyses and reviews (e.g., Savaiano & Hutkins, 2021; Szilagyi, 2015) confirm a beneficial, but moderate, effect. While Bifidobacteria are not a cure, their enzymatic activity and ability to colonize the gut provide a plausible mechanism for symptomatic improvement, and their use is supported by current scientific evidence as an adjunctive strategy for managing lactose intolerance.