There are very few supplements that have good evidence based medicine to support them. And the term supplement is really meant to be a dietary supplement, meaning something that is supplementing a dietary shortfall.
The greatest example is probably prenatal vitamins. There is good evidence based medicine to support using prenatal vitamins because the average person doesn’t get enough folate and micronutrients in their diet to support a real healthy pregnancy.
Another common one is if you have iron deficiency anemia, it’s really hard to get enough iron from your diet to treat that and so we might recommend an iron supplement.
So those are what we would consider sort of the evidence based examples – and that is not an inclusive list but that’s how to think about it.