Personally I take 5,000 IU of vitamin D in the winter, and less in the summer when I have more sun exposure (I live in a northern climate). Realistically if you

Personally I take 5,000 IU of vitamin D in the winter, and less in the summer when I have more sun exposure (I live in a northern climate). Realistically if you are trying to dial things in properly you should work in concert with a physician and base things off of longer term blood levels. The other supplement I take is B12, because the risk of over supplementation is seemingly none existent, and the magnitude of risk should I become deficient is unacceptably high. Past that, you are really running into issues that have too much to do with your individual diet and circumstances. People will note that magnesium deficiency is common in the US, but it’s also notable that Americans typically don’t eat many foods rich in magnesium (ie, nuts/seeds/whole grains/legumes and greens). Mineral absorption in particular tends to be the trickiest when it comes to supplementation, so it should really be addressed at the dietary level first. I will note, though, that I do use iodized salt, which is an exception to the above, and has proven to be an incredibly successful public health story that we often forget about these days.