A recent study has found that those smokers who take multivitamins may be smoking more cigarettes. This is an example of what psychologists call the licensing effect: people make a virtuous choice that permits them to make a poor choice later on.
In this case, smokers take multivitamins, a healthy choice that they believe reduces the risk of cancer and allows them to smoke more. In fact, there is no evidence that multivitamins protect against cancer.
The study describes two experiments run where participants were led to believe they were given a vitamin supplement.
Those in the first experiment who thought they had taken a vitamin pill smoked almost twice as much as those who knew they had taken a placebo (the control group) and reported greater feelings of invulnerability.
In the second experiment smokers who thought they had taken a multivitamin once again smoked more than the control group. But this time, researchers found that the amount of extra smoking rose if the smoker expressed a conscious belief that multivitamins increased health.
Lead author Wen-Bin Chiou says, "Smokers who take dietary supplements can fool themselves into thinking they are protected against cancer and other diseases. Reminding health conscious smokers that multivitamins don't prevent cancer may help them control their smoking or even encourage them to stop."