I think many health problems are related to not a few single causes, but to a cocktail of problems, some chemical, other purely lifestyle(sleep, food, exercise).
It's humbling how much AND little we know about processes in the body. Just read the article and comments some days ago about antidepressants. https://news.ycombinator.com/item?id=26197140
"Chemicals in plastics damage babies' brains and must be banned immediately (cnn.com)"
https://news.ycombinator.com/item?id=26211605