For years, doctors advised their patients that the only thing taking multivitamins does is give them expensive urine. After all, true vitamin deficiencies, such as scurvy and pellagra, are practically unheard of in industrialized countries. Now it seems those doctors may have been wrong. The results of a growing number of studies suggest that even a modest vitamin shortfall can be harmful to your health. Although proof of the benefits of multivitamins is still far from certain, the few dollars you spend on them is probably a good investment.
Or at least that's the argument put forward in last week's New England Journal of Medicine. Ideally, say Dr. Walter Willett and Dr. Meir Stampfer of Harvard, all vitamin supplements would be evaluated in scientifically rigorous clinical trials. But those studies can take a long time and often raise more questions than they answer. At some point, while researchers work on figuring out where the truth lies, it just makes sense to say the potential benefit outweighs the cost.
The best evidence to date concerns folate, one of the B vitamins. It's been proved to limit the number of neural-tube defects in embryos, and a recent double-blind randomized trial found that folate in combination with vitamin B12 and a form of B6 also decreases the reblockage of coronary arteries after angioplasty. Look for a supplement that contains 400 micrograms of folate.
The news on vitamin E has been more mixed. Healthy folks who take 400 IU daily (standard multivitamins usually contain 30 IU) for at least two years appear somewhat less likely to develop heart disease. But when doctors give vitamin E to patients who already have heart disease, the vitamin doesn't seem to help. It may turn out that vitamin E plays a role in prevention but cannot undo serious damage.
Despite vitamin C's great popularity and near ubiquity, consuming large amounts of it still has not been positively linked to any great benefit. The body quickly becomes saturated with C and simply excretes any excess.
The multivitamins question boils down to this: Do you need to wait until all the evidence is in before you take them, or are you willing to accept that there's enough evidence that they don't hurt and could help?
If the latter, there's no need to go to extremes and buy the biggest horse pills or the most expensive bottles. Megadoses can cause trouble, including excessive bleeding and neurological problems. One important caveat: it's easy to get too much retinol (preformed vitamin A) from supplements and diet, which may increase the risk of hip fractures and birth defects. So make sure that retinol is not the only source of vitamin A in your pills.
Multivitamins are no substitute for exercise and a balanced diet, of course. But it's hard to be healthy all the time. As long as you understand that any potential benefit is modest and subject to further refinement, taking a daily multivitamin makes a lot of sense.