Vitamins: What to Take, What to Skip

Beta-carotene

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 or other diseases. A 2004 study found that supplements might actually raise the risk of lung cancer in smokers. More recent research in the Journal of the National Cancer Institute also linked excessive beta-carotene intake through supplements with higher risk of lung cancer and heart disease, although more research is still needed.

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.

Calcium

Our bodies need calcium—mostly found in dairy products like milk, yogurt, and cheese—to maintain healthy bones and prevent osteoporosis. But most people don't have a true calcium deficiency (calcium inadequacy, when someone isn't getting enough of the mineral in their diet, is more common).

Bottom line: Supplements might not be 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, and too many calcium supplements can also lead to hypercalcemia, which can cause excessive thirst and bone pain. Speak with your doctor before 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

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). More research is still needed as to whether folate may help combat certain cancers and heart disease.

Iron

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. (You can also maximize your absorption with these meat-free iron combinations.) True iron deficiency is unusual, but 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.

Multivitamin

Research on multivitamins has been mixed, and the latest research doesn't show they can lower risk of heart disease, diabetes, or certain cancers.

Bottom line: Multivitamins aren't a bad idea if "you're on the go," Anderson says. "But don't expect major lifesaving benefits." But you should make sure you're not consuming too much of any one nutrient (especially if you're taking other supplements as well). And as always, you're better off getting vitamins through a varied diet with plenty of fresh produce, healthy fats, and lean proteins.

Potassium

Potassium can lower your risk of stroke and heart disease, and counteract the effects of too much sodium. It's found in bananas, raisins, leafy greens, oranges, milk, and many other common foods.

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.

Selenium

The body needs only small amounts of this antioxidant, found in meats, seafood, eggs, and bread. Although a study found that taking 200 micrograms daily reduced the risk of prostate, lung, and colorectal cancers, but other studies have been "complete flops," Anderson says. That includes a 2011 analysis and 2016 study, which found that men who took selenium and vitamin E didn't have lower risk of polyps.

Bottom line: Don't count on selenium to lower your chances of getting or dying from cancer. It's likely you're getting enough from food sources, anyway.

Vitamin C

This much-touted cure-all, found in citrus fruits, berries, broccoli, and green peppers, just doesn't make the grade when it comes to common-cold prevention. One study did suggest that taking vitamin C regularly might reduce the length of a cold by a day.

Bottom line: Try to get enough vitamin C through your diet. It's fine to take a supplement, especially if you're a smoker or nonsmoker who is often exposed to secondhand smoke. But there seems to be little point in upping your intake to combat sniffling and coughing.

Vitamin D

Vitamin D, which helps the body absorb calcium, is necessary for bone health. It's mostly accessible through sun exposure, as well as some food, such as fatty fish or fortified milk. Too little vitamin D can contribute to osteoporosis. Some evidence suggests that the vitamin may reduce protect against certain cancers, but the jury's still out on these benefits (and other research has linked vitamin D to greater risk of pancreatic cancer).

Bottom line: Very little sun is needed to get your quota of vitamin D, and some foods are fortified with it as well, meaning most people get enough of it. Supplements may be a good idea if you don't have much sun exposure, are over 50, or have dark skin, but speak to your doctor first.

Vitamin E

Vitamin E is an important antioxidant that plays a role in protecting cells from free radicals, strengthens your immune system, and can help slow macular degeneration. It's found in foods like wheat germ and sunflower seeds.

Once upon a time, researchers thought this antioxidant could protect the heart, but newer research hasn't found that it can prevent cancer or lower risk of heart attack or stroke. And too much vitamin E through supplements can increase risk of bleeding in the brain.

Bottom line: Forget the supplements and get E your vitamin E from food (oils like safflower, peanuts, eggs, fortified cereals, fruits, and green, leafy vegetables).