Chiou et al. suggest that illusory invulnerability created by taking dietary supplements licenses health-risk behaviors. Their abstract (slightly edited):
The use of dietary supplements and the health status of individuals have an asymmetrical relationship: The growing market for dietary supplements appears not to be associated with an improvement in public health. Building on the notion of licensing, or the tendency for positive choices to license subsequent self-indulgent choices, we argue that because dietary supplements are perceived as conferring health advantages, use of such supplements may create an illusory sense of invulnerability that disinhibits unhealthy behaviors. In two experiments, participants who took placebo pills that they believed were dietary supplements, compared with participants who were told the pills were a placebo, exhibited the licensing effect across multiple forms of health-related behavior: In a first experiment they expressed less desire to engage in exercise and more desire to engage in hedonic activities, and expressed greater preference for a buffet over an organic meal. In a second experiment they walked less to benefit their health. A mediational analysis indicated that perceived invulnerability was an underlying mechanism for these effects. Thus, a license associated with the use of dietary supplements may operate within cycles of behaviors that alternately protect and endanger health.