Micronutrient supplementation:
more is not better.
A recent editorial in the NEJM reminds of a truism that once an adequate
concentration of a nutrient has been achieved, additional intake has no effect.
So, unless one has a known deficiency of a nutrient, there is no good reason to
take in more of it. When attracted by purported benefits of supplements, one
should also beware of potential ill effects and unnecessary expense.