The idea that taking vitamin pills can’t hurt and might do some good recently became a harder sell after two studies suggested that the pills may actually increase the risk of death. In one study, involving more than 38,000 older women, taking a daily multivitamin was found to be associated with a 2.4% higher risk of dying over the two decades they were followed. The second study showed that men who took vitamin E supplements were 17% more likely to develop prostate cancer than nontakers.
Not surprisingly, the multivitamin finding got a lot of media attention—surveys show that at least half of U.S. adults regularly take vitamin supplements, and, of those, about 75% take multivitamins—and so it’s likely that millions of people are now worried that they may be at risk of early death from some sort of mysterious biochemical imbalance induced by doing what once seemed a no-brainer good thing. But the purported risk may not be real. In fact, my guess is that it’s not.
For one thing, the multivitamin data didn’t prove cause and effect. Rather, it merely showed an association between taking multivitamins and a slightly elevated mortality risk. (To establish cause and effect, you minimally need multiple, well-controlled studies showing a consistent pattern of harm across different groups of people exposed to a particular risk factor.) What might lie behind the association besides the unlikely possibility that multivitamins somehow abet mortal sickness? (I say unlikely because multivitamins generally contain only modest amounts of vitamins geared to meet well-established minimum daily requirements—they don’t deliver megadoses, as single-vitamin supplements often do, that are way beyond what you’d get from eating a balanced diet.)
Here’s what I think is really going on: After taking a daily multivitamin, people feel that they’ve at least partly shielded themselves from the effects of unhealthy lifestyles, making them a little less likely than they might otherwise be to skip the fries, to dispense with the daily soda or three, or to replace some of their TV time with exercising. Thus, my guess is that the slightly higher risk of death linked to multivitamins reflects a slightly elevated risk of being relaxed about doing all the wrong things, including health risks that multivitamins do nothing to offset, even if they do help make up for not eating enough fruits and veggies. Indeed, America’s obesity epidemic suggests that people generally aren’t all that worried about what their unhealthy lifestyles are doing to them. Multivitamin sellers’ pitches, even if just reciting the facts about how essential vitamins are to health, can’t help but feed their false sense of security. And as I’ve argued here and elsewhere, our sedentary, fattening lifestyles have much higher costs than is generally recognized—when it comes to the increasingly heavy burden of disease weighing down our society, it has the budget-busting effect of prematurely aging the entire population.
In contrast to the multivitamin study, which said little to nothing about cause and effect, the one on vitamin E and prostate cancer was a randomized clinical trial that added some compelling evidence to a growing body of clinical research that strongly suggests taking large doses of antioxidant supplements, in particular vitamins E, A and beta carotene, really does increase the risk of dying by about 5%. The discovery of this risk hasn’t proved that Denham Harman’s venerable free radical theory of aging is wrong. But as explained in my book, and in a piece I wrote for Boing Boing, the idea that popping big doses of antioxidants can prevent us from rusting out like old cars exposed to too many Boston winters now seems a dangerous myth propagated by antioxidant hucksters. One reason may be that taking such doses discombobulates our well-honed inner systems to fend off free-radical damage, ironically increasing our risk of such damage. And naturally-occurring free radicals are also thought to help induce cells with precancerous DNA damage to commit suicide—a process called apoptosis—before they turn into full-fledged tumor cells. Artificially quashing the radicals with big doses of antioxidants may interfere with such altruistic self-sacrifice for the greater good, enabling precancerous cells to stick around until further DNA damage turns them into unstoppable monsters. That definitely wouldn’t make for healthy aging.