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.
There are special capsules designed to survive stomach acid, but there are plenty of studies showing they’re not necessary in most/many cases.
Then I suppose stomach acid doesn’t kill everything.