Diet :: Taking too many supplements

"People tend to forget that a vitamin pill is a supplement -- it's meant to complement your diet, not act as a stand-in for the foods you don't eat," says Heller. What's more, she says, taking too many vitamins can end up sabotaging your good health.

"Every vitamin and mineral and phytochemical in our body works in concert with one another, and it's easy to knock that balance off if you are taking concentrated doses of single nutrients, or even groups of nutrients," says Heller.

Bradeis cautions that any diet plan that claims you must take a high-potency supplement to meet your nutritional needs should send up a red flag.

"It means that eating plan is not healthy," says Brandeis, "and it also means you are going to miss out on the synergistic health effects that can only come from whole foods -- including not only helping you to feel fuller longer, but also preventing cellular breakdowns important to preventing disease."

The solution:

Both experts recommend taking no more than one all-purpose multivitamin daily. Don't supplement your diet with individual nutrients without the guidance of your doctor, nutritionist, or other health expert. Keep in mind that the sales clerk in the health food store is usually not a health expert.