Popular gut probiotic completely craps out in randomized controlled trial

Any striking marketing claims in companies’ ads about the gut benefits of a popular probiotic may be full of, well, the same thing that has their target audience backed up.

In a randomized controlled trial, the probiotic Bifidobacterium animalis subsp. lactis—used in many probiotic products, including Dannon’s Activia yogurts—did nothing to improve bowel health in people with constipation, according to data from a randomized triple-blind placebo-controlled clinical trial published Wednesday in JAMA Network Open.

The study adds to a mixed and mostly unconvincing body of scientific literature on the bowel benefits of the bacterium, substrains of which are sometimes sold with faux scientific-sounding names in products. Dannon, for instance, previously marketed its substrain, DN-173 010, as “Bifidus regularis.”

Digested data

For the new study, researchers in China recruited 228 middle-aged adults, 85 percent of whom were women. The participants, all from Shanghai, were considered healthy based on medical testing and records, except for reporting functional constipation. This is a condition defined by having two or more signs of difficulty evacuating the bowels, such as frequent straining and having rock-like stool. For the study, the researchers included the additional criterium that participants have three or fewer complete, spontaneous bowel movements (CSBMs) per week.

The participants were randomized to take either a placebo (117 participants) or the probiotic (112 participants) every day for eight weeks. Both groups got packets of sweetened powder that participants added to a glass of water taken before breakfast each morning. In addition to a sweetener, the daily probiotic packets contained freeze-dried Bifidobacterium animalis subsp. lactis substrain HN019, which is used in some commercial probiotic products. The first dose had a concentration of 7 × 10⁹ colony-forming units (CFUs), then participants shifted to a daily dose of 4.69 × 10⁹ CFUs. Many probiotic products have doses of B. lactis in ranges from 1 × 10⁹ to 17 × 10⁹.