• Folic acid: Taking folic acid (also called folate) can reduce the risk of having a baby with a neural-tube birth defect.
    Shopping tip>> Women of childbearing age should consume 800 mcg daily.
  • Herbs: Black cohosh (Cimicifuga racemosa), saw palmetto (Serenoa repens), ginkgo (Ginkgo biloba), and the like often show up in multis, but usually in amounts too small to provide therapeutic benefits. "If you want to combat stress, taking 25 mg of ginseng in a multi might help," says Shari Lieberman, PhD, CNS, FACN. "But it isn't going to have the same effect as taking 200 mg of ginseng separately."
    Shopping tip>>Choose standardized extracts of herbs that address your primary health concerns.
  • Iron: Men and postmenopausal women should avoid multis that contain iron, which can build up in the body and increase the risk of heart disease, says Jennifer Nevels, NMD. Vegetarians and women with heavy periods, however, may need up to 18 mg of iron daily.
    Shopping tip>> Too much iron can be hazardous to your health, so consult a physician before adding in iron supplementation, Nevels says.

  • Vitamin D: This vitamin aids calcium absorption. A recent study found that women over 65 who supplemented with vitamin D and calcium had a reduced risk of falling (Archives of Internal Medicine, 2006, vol. 166, no. 4). Moreover, a review of 63 studies showed that getting enough vitamin D lowers risk for several cancers, including colon, prostate, and breast (American Journal of Public Health, 2006, vol. 96, no. 2).

  • Vitamin E and beta-carotene: Choose natural forms of these fat-soluble vitamins. "Synthetic vitamin E can have as little as one-eighth the activity of natural vitamin E, and synthetic beta-carotene can actually be dangerous," says Lieberman.
    Shopping tip>> Look for "natural" or "d-alpha" vitamin E and "natural" or "d-salina" beta-carotene.
Sources: Shari Lieberman, PhD, CNS, FACN; and Jennifer Nevels, NMD.