Since the Food and Drug Administration does not regulate most vitamin claims, supplement-makers are free to say whatever they want. Following are explanations as to which claims matter and which are just fluff. Men's Formula: Men need a multivitamin with no more than 8 or 9 mg of iron. Studies are testing whether selenium (200 mcg), vitamin E (400 IU) and lycopene (15 mg) can reduce prostate cancer risk. That is more of each than a typical men's multivitamin has.

Antioxidants: In the studies done so far, vitamins C and E and beta-carotene did not lower the risk of cancer or heart disease. Energy: Extra B-vitamins or vitamin C or E does not make you more energetic. Women's Formula: Pre-menopausal women need a multivitamin with 18 mg of iron. Post-menopausal women need no more than 8 or 9 mg. Iron is the only distinction between women's and other formulas that matters.

USP: The Unites States Pharmacopeia (USP) tests supplements if manufacturers pay fees to cover the testing. This mark means that the listed ingredients are in the supplement and will dissolve or disintegrate, not that the supplement is safe or has any benefits.

High Potency: To the FDA, a multivitamin can call itself "High Potency" if at least two-thirds of its nutrients have at least 100-percent of the Daily Value. To most people, "High Potency" means more than the Daily Value's. "Advanced", "Complete", or "Maximum" formulas can mean anything.

Stress Formula: There is no good evidence that the extra B-vitamins and vitamin C in "stress" formulas reduce stress or repair the damage it causes. What is more, these supplements often lack minerals.

Seniors: "Mature", "50+", or "Select" formulas often have less iron (good) and less vitamin K (not good). Unless you are taking blood-thinners like coumadin, your multivitamin should have vitamin K to reduce the risk of hip fractures.

Lutein: Even if lutein does help prevent cataracts, the 250 mcg in a typical multivitamin would not help much. In one study, people who ate 14,000 mcg of lutein a day (largely from green vegetables) had fewer cataracts than people who ate 2,000 mcg a day did.

Ginseng: In the best studies, ginseng does not boost energy. And a typical multivitamin has less ginseng (25 mg) than most studies use (at least 200 mg). Ginkgo: It is unclear whether large doses of ginkgo (180 mg to 360 mg) can sharpen the mind. But there is no evidence that the small amounts 925 mg to 60 mg) in a typical multivitamin do. Disclaimer: The FDA requires this disclaimer when the supplement makes a so-called "structure-or-function" claim, which may mislead consumers by implying that a vitamin prevents disease. For example, a claim such as "vitamin E reduces the risk of heart disease".