One of the factors in figuring out how safe a particular substance is that there may be gut bacteria, genetic, or other dietary confounders that make something

One of the factors in figuring out how safe a particular substance is that there may be gut bacteria, genetic, or other dietary confounders that make something fine for one person but poison for another. A spinach smoothy a day may be good for you but bad for me. A friends father recently had some issues with gout that were requiring some rather obnoxious dietary measures to tame. He found evidence in the literature about some bacteria strains that were found to be effective, found a source for the identified strains, and swears by the result.