(CBS) Talk about irony. People who take vitamin supplements may be more likely to take risks with their health, according to a surprising new study from Taiwan. Its authors conclude that taking vitamins may give an "illusory sense of invulnerability" that leads the pill-poppers to exercise less and to eat more than they should.
Researchers looked into the psychology of vitamin supplementation after noticing an "asymmetrical" relationship between public health and the use of vitamins.
"After reviewing the literature of the prevalence of dietary supplement use, it seemed to show that use of dietary supplements is increasing, but it does not appear to be correlated with improved public health," study author Wen-Bin Chiou of Taiwan's Sun Yat-Sen University said in a written statement.
So a group of researchers led by Chiou set up a pair of experiments in which identical placebos were given to a group of volunteers, some of whom were told that they had been given vitamin supplements and others told they had been given placebos.
In the first experiment, the volunteers who believed they had taken vitamins expressed less interest in exercise and a greater desire to engage in so-called "hedonic" activities - for example, digging in to a buffet than having an organic meal. In the second experiment, the volunteers who thought they had been given vitamins walked less to benefit their health than those who thought they were taking a placebo.
As Chiou explained the findings in in the statement, "People who rely on dietary supplement use for health protection may pay a hidden price, the curse of licensed self-indulgence."
One thing's for sure, vitamins and other dietary supplements are popular. Between 2003 and 2006, approximately 40 percent of men and women in the U.S. reported taking a multivitamin supplement. During the same time period, more than half of all adults reported using some form of dietary supplement.
The finding came as no surprise to researchers on this side of the Pacific. "We live in a society that is very oriented towards taking medication," Dr. Andrew Leuchter, director of the UCLA's Laboratory of Brain, Behavior, and Pharmacology, told msnbc.com. "People feel like they can take a pill and it will almost immunize them from any unhealthy lifestyle choices."
The study was published in the journal Psychological Science.