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Breakfast cereals can be a good source of folate and vitamins B12 and D.

By Jill Weisenberger, M.S., R.D., C.D.E.
Her Sports + Fitness Vitamins and minerals help give you energy, fight disease and increase athletic performance. But it's common for many American women to skimp on these health boosters and become dangerously deficient. Before rushing to the supplement aisle, recognize that the best health-promoting vitamins and minerals aren't found in pills. "Food first," says Kerry Neville, M.S., R.D., spokesperson for the American Dietetic Association. Neville recommends vitamin and mineral supplements only to augment an already balanced diet, or if you avoid whole food groups because of allergies, intolerances or other reasons, such as being a vegetarian. There are thousands of phytonutrients in food, she says, but only a few hundred have been researched. No pill can duplicate the chemical reactions of your breakfast, lunch and dinner. So head to the grocery store to get your hardworking body most of what it needs to carry you through the day and fend off illness. Here are some star nutrients that may need some pumping up in your diet.

Vitamin A

Vitamin A is a group of compounds--beta carotene and retinol among them--important in immune function, vision, bone growth and cell division. Fruits and vegetables provide vitamin A in the form of beta carotene and other carotenoids. Vitamin A from animal sources comes as retinol. You'll have no problem getting the RDA of vitamin A (2,310 International Units or IUs) if you eat five to nine servings of colorful fruits and vegetables daily. The best sources of beta carotene: orange fruits and vegetables such as carrots, sweet potatoes, cantaloupe and mangoes; green leafy vegetables such as spinach and kale; red fruits and vegetables like watermelon and tomatoes. For retinol, consume chicken liver, whole milk, fortified nonfat milk and other dairy products or eggs. Be careful when choosing a vitamin A supplement. Sometimes supplements can be harmful, says Edgar Miller, Ph.D., M.D., professor of Medicine and Epidemiology at Johns Hopkins Medical University. Consider what scientists learned about beta carotene supplements in the '80s and '90s. Researchers observed that people who ate ample fruits and vegetables rich in vitamin A had lower rates of lung cancer. However, they also found that male smokers receiving beta carotene supplements were more likely to develop lung cancer. Taking large doses of antioxidant supplements may interfere with the body's own defense mechanisms, suggests Miller. Supplemental vitamin A, found in multivitamins, is often made of retinol (often seen as vitamin A palmitate or acetate), beta carotene or a combination of both. Excess retinol is associated with birth defects, liver disease, osteoporosis and hip fracture. (Don't take a multivitamin that lists a Daily Value (DV) of more than 100 percent for retinol.) Similarly, the IOM does not recommend beta carotene supplements for the general population. So, aim for a multivitamin with both sources listed, and if it simply lists vitamin A, leave it alone since you don't know the source.

Folate
This B vitamin is needed for DNA synthesis and cell division. During growth periods such as pregnancy and infancy, folate requirements increase to keep up with rapid cell division. Since the body absorbs folic acid, the synthetic form of the vitamin, more easily than the food form, the FDA requires all foods designated "enriched" to have added folic acid, says Lynn Bailey, professor of nutrition at the University of Florida. This ensures that women of reproductive age consume enough of the vitamin to reduce the risk of neural tube defects such as spina bifida and other birth defects. Folate is required for the synthesis of blood and muscle cells, so a deficiency means less oxygen-carrying ability and a decrease in your physical performance, says Bailey. "Taking extra folic acid, however, does not enhance your ability to perform athletic activities." Some studies suggest that folate is important in the prevention of heart disease, cancers and Alzheimer's disease. Aim for 400 micrograms (mcg) per day unless you're pregnant or planning to become pregnant soon. Then you'll need 600 mcg daily. Boost your folate levels with fortified breakfast cereals, fortified breads, dried beans and peas, green leafy vegetables and oranges.

Vitamin B12
Every food that comes from animals contains this vitamin, which is necessary to make DNA and maintain healthy nerve and red blood cells. National health surveys show that most Americans consume adequate amounts of vitamin B12. However, strict vegetarians will need to supplement, as will older people lacking the stomach acid necessary to extract the vitamin from food. If you are older than 50 experts advise that you get 2.4 mcg from a supplement or fortified food such as breakfast cereal. It often takes years to deplete the body's normal reserves, so deficiency symptoms appear slowly. They include anemia, fatigue, depression and nerve damage such as tingling in the hands and feet. If the deficiency persists, the nerve damage will be permanent. To avoid developing a deficiency, eat fortified breakfast cereals, beef, fish, poultry, pork, dairy and eggs.

Vitamin C
Vitamin C acts as an antioxidant, aids the immune system and is necessary for the synthesis of collagen, the major protein of bone, teeth, skin, cartilage and tendons. Reports of large doses of vitamin C preventing the common cold are controversial. The general consensus is that although vitamin C doesn't prevent a cold, it can reduce the severity of symptoms. Eating plenty of fruits and vegetables will assure you consume several times the RDA. (The RDA for women is 75 mg, the amount in about 5 ounces of orange juice or just over a cup of cantaloupe.) Some experts recommend amounts several times the RDA, believing it helps prevent chronic diseases. Sources high in vitamin C: broccoli, sweet peppers, tomato products, citrus fruit, cantaloupe, guava, kiwis and strawberries

Vitamin D
This vitamin is actually a hormone made in the skin. UV rays from sunlight trigger its synthesis. Thus dark-skinned people, those who are rarely outdoors, those living in northern latitudes and older adults must be especially careful to get adequate vitamin D from food or supplements. Most commonly recognized for its role in bone health, vitamin D is also studied for its possible role in the prevention of many chronic diseases. Studies suggest it can reduce the risk of hip fractures; protect against cancers of the colon, breast, lung and digestive tract; and decrease the inflammation associated with arthritis. The recommended intake of vitamin D is 200 to 600 IUs (you need more as you get older). Many researchers think it should be much higher. Be careful to stay under 2,000 IUs, the safe upper intake level for adults. Salmon, tuna canned in oil, sardines canned in oil, fortified milk, egg yolks and fortified cereals are all good sources of vitamin D.

Potassium
Throw a banana in your gym bag and you'll get an instant pick-me-up after a workout. Why? Because bananas are loaded with potassium, crucial for muscle contraction, nerve transmission and fluid balance. Potassium lessens the risk of developing kidney stones and possibly minimizes bone loss with age. And potassium-rich foods help prevent and treat high blood pressure, which raises your risk of stroke, heart disease and kidney disease. Potassium blunts the effects of excess sodium--75 percent of women take in too much sodium--which causes blood pressure to rise. The average American woman eats less than half the Institute of Medicine's (IOM) recommended 4,700 milligrams (mg) of potassium each day. Boost your intake by adding sweet potatoes, white potatoes, leafy greens, tomatoes, melons, mangoes, oranges, peaches and yogurt to your diet.  

Calcium
Seventy-eight percent of women don't get enough calcium, which is crucial for your health. More than 99 percent of the body's calcium provides structure for your bones and teeth. The remaining calcium goes to the blood and muscles, where it helps the muscles contract, expands and contracts blood vessels, and sends messages through the nervous system. Calcium is so vital that it must be constantly present in blood. When your calcium intake is inadequate, your body steals it from the bones to supply your blood, which can lead to weak bones and osteoporosis. Researchers have studied calcium's potential role in a variety of illnesses. According to the National Institutes of Health Office of Dietary Supplements, a diet rich in fruits and vegetables and high in calcium reduces blood pressure, lessens the risk of kidney stones (contrary to previous beliefs) and may help fight colon cancer (early research results are promising but inconclusive). Aim to consume 1,000 to 1,200 mg of calcium daily. Your best sources: milk and other dairy foods, calcium-fortified juices and soymilk, sardines, canned salmon with bones, tofu, leafy greens and canned beans. If you don't eat dairy products, look at your calcium intake carefully. To get the calcium in 8 ounces of milk, you'll need to eat 8 cups of cooked spinach, 2 1/2 cups of cooked broccoli, 1 1/2 cups of cooked kale or 3 ounces of sardines. If you're not getting enough, you may need to consider supplements. Calcium supplements are the number one selling mineral supplement, and the two main forms are calcium carbonate and calcium citrate. They are similarly well absorbed for most of us with adequate stomach acid. For those with lower levels of stomach acid--often people with anemia, depression, asthma, osteoporosis and other diseases--calcium citrate is a better choice. Otherwise choose calcium carbonate because it's cheaper, and the pills are smaller. If you need to get more than 500 mg of calcium from supplements, split your dose into no more than 500 mg at a time since absorption decreases as dosage increases. Look for a supplement containing vitamin D, which aids calcium absorption.

Magnesium
This mineral is key to more than 300 enzymes that regulate biochemical reactions throughout the body. You need magnesium to extract energy from food and for normal bone metabolism (50 percent of the body's magnesium is in the bone), muscle and nerve function and blood sugar regulation. And your risk of developing both high blood pressure and diabetes drops as your magnesium intake increases. A recent study in the Journal of Internal Medicine found that for every 100 mg increase in magnesium, the risk of developing type 2 diabetes fell about 15 percent. The Recommended Dietary Allowances (RDAs) of magnesium for women range from 300 to 360 mg, depending on your age and whether you're pregnant. (You need more when you're expecting.) Get most, if not all, from your diet. Spinach, artichokes and other green vegetables, dried beans, nuts, seeds and whole grains are all good sources. You're advised not to take more than 350 mg from supplements.

Iron
Low iron means low energy. Almost two-thirds of your body's iron is found in hemoglobin, that part of the red blood cell that carries oxygen throughout your body and provides energy. Iron deficiency is most common in women with increased needs for this mineral--teenagers, those with heavy menstrual losses and pregnant women. Avoid this energy-zapping deficiency by helping your body grab iron from food. Iron in meat proteins, also called heme iron, is well absorbed and largely unaffected by diet. But absorption of nonheme iron (from plants) is hugely influenced by diet. Both meat proteins and vitamin C enhance your body's ability to take in nonheme iron. If you rely on vegetable sources of iron, include vitamin C-rich foods at every meal. Get iron from liver, beef, oysters, fortified cereals, legumes, lentils and spinach. Aim for 18 mg per day until you reach age 50. Then your needs decrease to only 8 mg. If you don't need extra iron, don't take it. Some evidence suggests that iron stimulates the activity of free radicals, highly reactive molecules capable of causing cell damage.