As I understand it, If you have a even a moderately varied diet, multivitamins and supplements have little effect. If you have a hole in your diet, or you have

As I understand it, If you have a even a moderately varied diet, multivitamins and supplements have little effect. If you have a hole in your diet, or you have a condition that prevents eating certain foods, supplements are needed to keep you healthy. It is also worth mentioning that although things are labeled in a 'daily recommended' intake, it takes months or years for symptoms to develop. I don't like people labeling them as 'ineffective', because they definitely prevent very real and life destroying conditions like cretinism and rickets. This is mostly because people think 'if I need this to be healthy, then having too much of it should make me super healthy', which is not the case. If you get enough (which most people in developed countries do) then your body can do its various functions. I've heard the metaphor 'giving a mason more bricks than he needs won't make him work faster' or something like that.