I am continually astounded by how much, and at the same time how little we know about how our own bodies work.
claims like x improves y are abundant. sadly we don't often see the %quantitative improvements and fall into "every little bit helps"
then we get another claim like "a prevents b", then blindly follows. while a and x are good in its own rights, the 'interaction' effect is so complicated that taking them will become net negative