My girlfriend falls for a lot of this shit. It's in her family on her mother's side and it apparently goes back generations. I have assigned myself the job of quietly making sure she doesn't hurt herself. I don't try to fight her on ineffective placebo shit, just the stuff that might hurt her. Which, honestly, isn't much. So I find myself fact-checking some of the dumber shit she gets off Pinterest. On the topic of probiotics I can say that theideabehind it is sound. Theideathat there are bacterial fauna that can hurt us and bacterial fauna that can help us came up in the early 20th century by a guy who went to the school of Louis Pasteur and is unquestionably a sound one. The fact that there are microbes in our gut that were passed to us in the placenta that help us digest and operate is a firm fact. However, the rub lies in the amount of supposed understanding and control we have over these colonies of microbes. We know they are there, we know they are legion, but we cannot describe with any level of detail how these colonies interact with one another or what the addition or subtraction of any numbers of any of them might do to the overall outcome of the human in which they reside. Not to mention the fact that every human has a different specific colony. It would be like saying, "I know each and every floral and faunal species that exists in every different forest on Earth and I can with absolute certainty know that if we increase the number of black ants by this exact amount in each forest, that the overall health of these forests will unquestionably improve." It's just too complicated and nebulous a thing to say with any degree of confidence.
So while the basic idea of probiotics is a sound one, our collective understanding and level of technological control over them is still in the stone-age and the claims being made by the manufacturers are all inflated and bogus. The good news is that for the most part, they seem to have no difference in outcome than placebo so all you are really losing is a bit of money.