There is an interesting article in The Atlantic called ‘The Vitamin Myth’ on the origin of the trend for taking mega-dose vitamin supplements, as well as the research that shows taking high doses of supplements can actually be harmful to health in some cases.
The article makes the same errors that it accuses the vitamin proponents of, e.g. citing evidence that supports its point without fully considering other factors, but it makes for an interesting read. And it is always a good idea to get your nutrients from whole foods, rather than rely on popping pills.
This is an excerpt:
Antioxidants can also be found in fruits and vegetables — specifically, selenium, beta-carotene, and vitamins A, C, and E. Studies have shown that people who eat more fruits and vegetables have a lower incidence of cancer and heart disease and live longer. The logic is obvious: if fruits and vegetables contain antioxidants — and people who eat lots of fruits and vegetables are healthier — then people who take supplemental antioxidants should also be healthier.
In fact, they’re less healthy.
In 1994, the National Cancer Institute, in collaboration with Finland’s National Public Health Institute, studied 29,000 Finnish men, all long-term smokers more than fifty years old. This group was chosen because they were at high risk for cancer and heart disease. Subjects were given vitamin E, beta-carotene, both, or neither. The results were clear: those taking vitamins and supplements were more likely to die from lung cancer or heart disease than those who didn’t take them — the opposite of what researchers had anticipated.