(VNF) - 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. 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. Here's a quick guide to beneficial nutrients and what they can do for you.

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. In fact, a 2004 study found that supplements may actually raise the risk of lung cancer in smokers.

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.

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

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.

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.

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.

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.

Multi-vitamin

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.

Multivitamins aren't a bad idea if you're on the go, but don't expect major lifesaving benefits.

Potassium

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.

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. A study found that taking 200 micrograms daily reduced the risk of prostate, lung, and colorectal cancers, but other studies have been "complete flops".

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.

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, not food. Too little vitamin D can contribute to osteoporosis and rickets in children. Some evidence suggests that the vitamin may reduce the risk of type 1 and 2 diabetes and multiple sclerosis, but the jury's still out on these benefits.

Even though very little sun is needed to get your quota of vitamin D, and some foods are fortified with it, deficiencies aren't unusual. Supplements might be a good idea, especially if you don't have much sun exposure, are over 50, or have dark skin.

Vitamin E

Once upon a time, researchers thought this antioxidant could protect the heart, but a large trial published in 2005 found that 600 international units (IUs) every other day neither prevented cancer nor lowered the risk of heart attack or stroke in middle-aged and older women. (More recently, a 2008 study found no benefit of 400 IUs every other day in middle-aged and older men.)

Forget the supplements and get your vitamin E from food (oils like safflower, peanuts, eggs, fortified cereals, fruits, and green, leafy vegetables). Bear in mind that cooking and storing foods with vitamin E can reduce the amount you're getting.

( Compiled by VNF )