What are the food supplements that, to the best of our current medical knowledge, are actually healthy and everyone should consider taking?

I'm not sure if this is the sort of thing you're talking about, but I switched from using regular table salt to Losalt. It tastes the same but it has only a 3rd of the sodium as regular salt. A lot of our food already have salt in them, so this is an easy way to reduce your sodium intake. We do need sodium, but we can also have too much of it.