The "eating foods, mostly plants, not too much" is a Michael Pollan line. One of Pollan's many points is that there is quite a bit of difficulty in separating o

The "eating foods, mostly plants, not too much" is a Michael Pollan line. One of Pollan's many points is that there is quite a bit of difficulty in separating out the good stuff from the bad stuff in foods due to chemical interactions. His general reasoning is along the lines of "There are x thousand different chemical compounds in an orange, it's very difficult to say, well it's the Vitamin C that's the important one." (scurvy notwithstanding) A good example of something like that is B12 and Iron Deficiency. You can be ingesting a good amount of Iron supplements but not have your actual Iron levels increase much if you lack B12. http://www.netdoctor.co.uk/diseases/facts/anaemiab12.htm http://www.netdoctor.co.uk/diseases/facts/anaemiab12.htm That's not to say that there aren't some pretty clear wins (Vitamin D comes to mind) from taking supplements, just that the actual benefits are often less clear than some of the literature would state.