Vitamins and minerals are essential to any diet, and research suggests they may help prevent cancer and heart disease, not to mention other health problems. But reality check: Many studies have been conducted on vitamin-containing food, but not necessarily supplements.
In fact, if you eat a diet rich in fruits, vegetables, and fortified food, you're probably getting all you need. But supplements do offer an easy, just-in-case form of health insurance.
Do you need them? Here's a quick guide to beneficial nutrients and what they can do for you.
Found in carrots, sweet potatoes, and green peppers, among other foods, this antioxidant is converted in the body to vitamin A and is important for healthy vision, a functioning immune system, and good skin. But the evidence isn't really there to recommend it for staving off cancer. In fact, a 2004 study found that supplements may actually raise the risk of lung cancer in smokers.
Bottom line: Skip the supplements if you're a smoker, and try to get your beta-carotene from fruits and veggies, whether you smoke or not.
Our bodies need calcium—mostly found in dairy products like milk, yogurt, and cheese—to maintain healthy bones and prevent osteoporosis.
Bottom line: Supplements aren't a bad idea if you hate dairy (and can eat only so much kale and canned sardines), but you may want to skip them if you're prone to kidney stones or are a female over 70. A 2010 report linked supplements to heart-attack risk in older postmenopausal women. If you decide to go with supplements, don't take more than 500 milligrams at a time, and pair them with vitamin D to improve calcium absorption.
Folic acid, which prevents neural tube defects such as spina bifida in babies, is found in fortified breakfast cereal, dark green vegetables, legumes, citrus fruit juice, bread, and pasta.
Bottom line: Getting 400 micrograms a day of this B vitamin, and 600 if you are pregnant or lactating, is a no-brainer. That amount should come from food, supplements, or both, according to the National Institutes of Health (NIH). The jury's still out as to whether folate combats cancer, heart disease, or mental illness.
You may not love the foods highest in iron (liver and other organ meats), but the mineral is critical for the proper functioning of red blood cells and, therefore, the prevention of anemia.
Bottom line: Try to get iron from dietary sources, which also include lean meats, seafood, nuts, and green, leafy vegetables. However, you may need a supplement if you're anemic, or your doctor might prescribe them before surgery, says Jessica Anderson, a registered dietitian with the Coastal Bend Health Education Center, at the Texas A&M Health Science Center, in Corpus Christi. Women, especially those who are pregnant or menstruating, might also benefit.
There is limited evidence that multivitamins may help prevent breast cancer, and an NIH panel in 2006 wasn't convinced that popping the pills was worth it. Neither is the Agency for Healthcare Research and Quality, which said the only benefit could be to reduce cancer risk in people with poor nutrition. And a large 2009 study failed to find any beneficial effects of the vitamins for cancer or deaths among postmenopausal women.
Bottom line: Multivitamins aren't a bad idea if "you're on the go," Anderson says. "But don't expect major lifesaving benefits."
Potassium can lower blood pressure, even out irregular heart rhythms, and counteract the effects of too much sodium. It's found in bananas, raisins, leafy greens, oranges, and milk.
Bottom line: Consider a supplement if you're taking potassium-depleting diuretics for a heart condition, or if you're African American, a group that's at higher risk for hypertension and heart disease. Keep in mind that too much potassium can be harmful to older people and people with kidney disease.