If you’re familiar with the history of Activia, you may not be surprised.
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 Wednesday in JAMA Network Open.
A couple of years back I read of a study which concluded that because we are all so unique, there is no one size fits all probiotic. It's a crap shoot if you want to find one that works for you.