Friday, June 3, 2011

Negative Behavioral Effects of Multivitamins: Supplement Use Disinhibits Unhealthy Behavior

Do you take a multivitamin? Fish oil? A natural greens supplement? Fine. Probably all healthy stuff, but have you ever thought about your reasons for doing so? I hope its not, because you think that you "cannot get all your vitamins, minerals and healthy fats from your diet". A recent study suggests that, for many people (the knowledgeable students of the SuppVersity excluded), this way of "taking the easy way out", turns out to have dangerously unhealthy consequences.

As a research group from different Taiwanese University (Chio. 2011) has recently established, the consumption of dietary supplements has "ironic effects" in that it conveys the "illusion of invulnerability" and thus "licenses health risky behavior".
Figure 1: Preferences of subjects thinking they received vitamin supplement vs. control (data adapted from Chio. 2011)
The scientists had conducted two experiments in the course of which subjects received either a purported vitamin supplement or placebo (the study was randomized and both pills had no active ingredients) and correlated perceived vitamin / placebo intake with the subjects' preferred leisure-time activity and their food choices in a cafeteria setting (experiment 1), as well as an (from my perspective, less significant) experiment that involved voluntary walking (experiment 2). What the scientists found was that
Participants taking a dietary supplement (actually a placebo) exhibited the licensing effect across multiple forms of health-related behavior: they expressed less desire to engage in exercise and more desire to engage in hedonic activities, preferred a buffet over an organic meal (Experiment 1), and walked less to benefit their health (Experiment 2).
Image 1: Multivitamins may be beneficial,
as long as you do not take them as an
excuse for an overall unhealthy lifestyle.

Obviously, the subject who thought they had just consumed a boatload of healthy vitamins did not consider it necessary to take additional measures to benefit their health. Knowing that you probably would not fall for the misconception that vitamin supplementation licenses unhealthy behavior, I still insist that these results are of utmost importance for you as a (self-)informed consumer, as they do in fact validate a hypothesis I have been bringing forward for years: Epidemiological studies on the beneficial or not so beneficial health effects of (especially) vitamin supplements are intrinsically flawed right from the start. If vitamin supplementation promotes unhealthy behavior, the latter could easily (over-)compensate any beneficial effects of vitamin supplementation, so that a study where you interviewed a given number people and correlated their use of vitamin supplements with a selected health marker could easily fool you into believing that vitamins are unhealthy, despite the fact that it is the wrong food and lifestyle choices that result from the feeling of "invulnerability" that cause the health problems in your subjects.