Multivitamins—a Health Hazard?

Dr. Simon (Courtesy of Harvard Health Publications)

Some bad news for all you guys out there dutifully downing a daily multivitamin: They don't work and are possibly hurting you, reports March's Harvard Men's Health Watch. Harvey Simon, that newsletter's editor, has launched a fusillade against "vitamania" with an article suggesting that men abandon the notion that those little brown pills are harmless insurance policies against chronic diseases. Rather, he argues, men (and women, too) should consider evidence that multivitamins could be hastening the growth of tumors.

Vitamania, the Harvard newsletter notes, came to the fore in the late 1980s and early 1990s, when a series of observational studies (which aren't rigorous and cannot prove cause and effect) showed that certain antioxidants, including vitamins A, E, and C, could protect against heart disease, cancer, and other maladies. Those studies, along with a permissive 1994 law called the Dietary Supplement and Health Education Act that allowed manufacturers to sell supplements without first proving that they provide health benefits, spurred a booming multibillion-dollar supplement industry.

It turns out that those original antioxidant studies were wrong, more recent randomized studies that do prove cause and effect have shown. New Scientist slogs through some of the disappointing findings, for example, on beta carotene, vitamin E, and vitamin C. In most instances, the clinical trials have shown that vitamins have no effect and, in some, that they may even cause harm. Just today, new evidence emerged linking vitamin E supplements to an increased risk of lung cancer. Likewise, recent clinical trials have dashed hopes for vitamins B6 and B12. And concern has fallen especially hard on the B vitamin folate. As we reported in August, researchers are increasingly wary that megadoses of folate—which many foods are fortified with—promote colon cancer. The extra folate from a multivitamin, Simon believes, could be enough to push men into danger.

Simon has ditched his multivitamin. (Though he does recommend sticking with vitamin D, one vitamin for which the link to health benefits has not yet crumbled.) For me, too, the choice is easy. I've long been convinced that the smartest and safest way to get all the antioxidants and vitamins I need at doses my body can handle is by eating a balanced diet rich in plants, whole grains, and legumes—without the help of supplements. My parents taught me as much when I was a kid, and many of the nutritionists I've interviewed for U.S. News are coming to the same conclusion: that real foods (fresh fruits and vegetables especially) are far superior sources of vitamins and minerals than supplements.

But I wouldn't expect multivitamins to go down without a fight. The supplement industry is sure to fire back with a slew of evidence showing that multivitamins are helpful. And top nutritionists, such as Harvard University's Walter Willett, have endorsed daily multivitamins in the past.

Where do you stand?