Your multivitamin may have a sinister side,

according to a study from Taiwan. People who were given a sugar pill they thought was a multi were more likely to opt for a buffet lunch and take short cuts while walking than people who knew they were popping a placebo. We may believe that vitamins offset bad habits, says study author Dr Wen-Bin Chiou. As you take your multi, plan at least three healthy actions to take that day.

And remember: Swallow your multi with water, never tea. The polyphenols in tea can affect mineral absorption.