When I recently speculated that taking vitamin pills may contribute to unhealthy choices because many people assume the pills shield them from the choices’ ill effects, I figured there was no way to support my hunch. But I was mistaken: A recent Taiwanese study demonstrated that taking multivitamins does indeed make people feel protected against health hazards and thus more likely to indulge in unhealthy choices.
Led by Wen-Bin Chiou at National Sun Yat-Sen University, the researchers gave daily placebos for a week to 82 adults (45 women, 37 men, average age 31). They told half of the group that they were taking multivitamins, and at the end of the week administered surveys on the subjects’ health-related inclinations. The results: Those who thought they were taking vitamins reported a 44% higher tendency to partake in risky activities (examples included casual sex, sunbathing, and binge drinking), and a 61% higher preference for all-you-can-eat buffets over healthy meals, compared with those who knew they were taking placebos. The “multivitamin” group also reported exercising 14% less. The researchers concluded that multivitamin takers may experience an “illusory invulnerability” contributing to all kinds of risky behaviors.
In a related study, Chiou and colleagues gave placebos to a group of smokers, some of whom were led to believe that they were getting multivitamins or another dietary supplement perceived as protecting health, such as vitamin C. As expected, those who thought they were taking dietary supplements smoked more cigarettes. And the more positive that smokers felt about the presumed benefits of the fake supplements, the more they smoked. I find this study particularly ironic because taking beta-carotene and vitamin A can substantially increase a smoker’s risk of getting lung cancer.
One reason all this is interesting is that a few years ago prominent biochemist Bruce N. Ames, at the Children’s Hospital of Oakland Research Institute, proposed an intriguing theory about aging and vitamins that suggests taking multivitamins might well be a good thing as a general rule. Briefly, his “triage hypothesis” holds that evolution has geared our bodies to selectively allocate scarce micronutrients (essential vitamins and minerals) to support metabolic functions that help insure near-term survival, which means that short micronutrient rations are given to less-urgent metabolic processes when diets aren’t well-balanced—a dietary plight that was likely often the case for our ancestors, and that Ames argues is probably also the case for many people today who consume a lot of junk food. Unfortunately, the short-rationed metabolic processes tend to be the very ones that help protect us from the relatively slow-acting damage that probably underlies aging, such as repairing frayed DNA (damaged DNA can lead to cancer and many other diseases of aging).
Like most hypotheses related to nutrition, this one is controversial and hard to prove. But it is consistent with the generally accepted evolutionary theory of aging, which holds that natural selection works to keep us healthy and vibrant when we’re young, but effectively loses interest in us as we grow older, allowing us to get trashed by things such as free-radical damage to DNA and other biodegrading insults—as evolutionary biologist George Williams observed in 1957, whenever there’s a tradeoff that evolution has to make affecting health and survival, it invariably favors the choice that promotes vibrancy early in life, even if that has dire delayed effects that play out in later life. Ames’s theory can be seen as an offshoot of this “antagonistic pleiotropy” principle.
So does it make sense to take a daily multivitamin after all? Ironically, it would seem the answer is most likely to be yes for those who tend to eat junk and make other poor lifestyle choices, and thus who would also be the kind of people most likely to suffer ill effects caused by the illusory invulnerability that goes with popping vitamins. As for me personally, I’ve decided to pop a multivitamin on the relatively rare days when I remember to do so, and on those days to take special pains to steer clear of orgies, sunburns, binge drinking, and all-you-can-eat restaurants.