Q: Are vitamin and other daily supplements proven effective?
All the following answers to this question are correct: Yes, No and It Really Depends.
Your lifestyle, your genetics, your dietary regimen and your health status will all be factors influencing your supplement regimen intake, efficacy & requirements…oh, yes and the latest nutrition fashion and of course, what currently “everybody knows”.
Compounds like creatine,, and can be extremely useful in some cases and not so much in others.
Too much can be as much of a problem as too little, perhaps more so. Fat soluble vitamins like A & D can be a problem. Too many and too much anti-oxidants can be a problem (oxidants serve a vital purpose, too). Many nutrients and supplements reflect ausage pattern (i.e. better, better, better, best, not good, worse, bad, very bad, etc.).
So Caveat Emptor, read some good stuff (some good sources are, Medscape, ) do some homework, try to be a critical thinker and be able to differentiate between plausible and implausible information so you are able to handle these nutritional tools, but also put them to good use.