Experts have suspected for some time that supplements may only be beneficial if a person is deficient in a nutrient.
And excess may even harm, as the study in Archives of Internal Medicine finds.The study was based on recall, a big caveat, but the idea is that enhancing a balanced diet with supplements, particularly iron, can be harmful. The conclusion is that supplements should be taken only by people deficient in some nutrient. Unless it's calcium -- according to this study, supplementing with calcium may extend your life. The authors don't know why.
So much for the antioxidants, beta carotenes, bone strengthener, flu-resisting, pep and vim guaranteeing One-A-Days. Watch what you put into your body, apparently, if you want to have that body for as long as possible.
Now, this study is about 'older women', but why should we assume that's the only impact of vitamin o'ding? If we can't trust the legions of studies (expensive, by the way, on your tab) that have pushed us towards vitamin-doping, why trust this one? If alphabet popping (A's, B's, C's, D's, and E's) is not so good for older women, why would this not also be so for younger ones, or for men, even? After all, a lot of things may change in a lifetime, but not genotypes, and here 'older' includes women just in their 50's.
How is it that something that would seem to be rather straightforward is still poorly understood? Vitamins are easy to identify, specific molecules, and pill dosages are also clear. If we can't actually estimate exposure because we don't know how often respondents actually pop their V's, or how much they get the old fashioned way (by eating food), then perhaps we can't totally trust the studies or the studies can't adequately evaluate things. They have to do this by statistical methods--more vitamins leading to statistically significant lower lifespans (significance doesn't mean importance, by the way, as we have often said, and the significance level by which one claims to have made a finding is inherently a subjective judgment).
The problem is not a criticism of the authors of this report--they do or don't deserve that based on the paper itself, nor of the journals (though, don't they always deserve it for over-dramatising results?). The problem is in the nature of this kind of science, or the kinds of questions being asked. The fault if there is one, is in assuming that this kind of knowledge is more sound and stable than it really is. For example, suppose the study is as solid as the rock of Gibraltar. Effects of B6 on lifespan may be affected by all sorts of other lifestyle factors. The same may not be found in, say, Burkina Fos0 today, or say, Norway twenty years from now (when you will have to worry about them!).
Evolution and many other aspects of the life and health sciences share these problems, but none of these fields (yet?) have the level of serious, basic reflection it may take to do better or to ask better questions. Until this happens, we will be stuck with the question of whether or not to be Tocopherol topers.