These nutrients are what keep your body functioning at its best―building strong bones; improving brainpower, mood, and memory; and possibly helping the immune system ward off ailments both small (a cold) and large (cancer).
"Vitamins should be used only as supplements to the diet, not substitutes for healthy food," says Jeffrey Blumberg, Ph.D., director of the antioxidant research lab at Tufts University, in Boston.
While there are hundreds of nutrients, the following information explains the ones you need to consume every day, what they do, and how to get them from your diet.
What it does for you: The B complex of vitamins (especially B6 and B12) keep blood, nerves, and the immune system functioning properly. A deficiency may be a risk factor for heart disease and stroke.
Vitamins B6 and B12
How much you need daily: The recommended dietary allowance (RDA) is 1.3 milligrams for B6 and 2.4 micrograms for B12.
Best food sources: B6 is plentiful in whole grains, bananas, beans, nuts, wheat germ, chicken, and fish. B12 is found in beef, pork, poultry, eggs, fish, and dairy.
How to eat enough of it: One cup of plain yogurt and a banana, one ounce of sunflower seeds, and three ounces of roast beef will fill your B12 and B6 quotas. B12 is found only in animal products, so vegans should take a supplement.
What it does for you: Vitamin C is an antioxidant that has been shown to fight DNA-damaging free radicals. It may help to maintain a healthy immune system and boost HDL, the so-called "good" cholesterol.
How much you need daily: Seventy-five milligrams, but some experts recommend getting at least 200 milligrams. As for megadoses of C to prevent colds, there's no scientific evidence that they accomplish anything.
Best food sources: Citrus fruits and juices, strawberries, red and green peppers, Brussels sprouts, broccoli, spinach, kale, and collard greens.
How to eat enough of it: Just one orange almost gets you to the RDA. Eat your recommended five servings a day of fruits and vegetables and you shouldn't be lacking in C.
CalciumWhat it does for you: It is essential for bone health and plays an important role in preventing osteoporosis.
How much you need daily: Up to age 50, women should get at least 1,000 milligrams daily; those over 50 should get at least 1,200. The body can't absorb more than 500 milligrams of calcium at a time, so small doses are best.
Best food sources: Dairy products are the most calcium-dense foods, but smaller amounts can be found in legumes and dark green, leafy vegetables.
How to eat enough of it: An eight-ounce glass of skim milk, one cup of yogurt, one cup of cooked spinach, and one fig will get you to your calcium goal. If you don't eat dairy, look for calcium-fortified soy milk or orange juice.
What it does for you: It enhances calcium absorption. A vitamin D deficiency can lead to osteoporosis and has been linked to certain cancers, as well as to multiple sclerosis, type 1 diabetes, and other chronic illnesses.
How much you need daily: Two hundred IUs for women up to age 50, and 400 to 600 IUs for those over 50.*
Best food sources: Although some is found in fatty fishes, like tuna and salmon, most of our vitamin D comes from fortified foods, like milk and cereal. The body also produces its own vitamin D when exposed to sunlight.
How to eat enough of it: If you're under 50, one 3 1/2-ounce serving of salmon or two cups of fortified milk will give you the RDA. Ten to 15 minutes of sunlight (with no sunscreen) two to three times a week is usually sufficient, too.
*Fat-soluble vitamins, such as D and E, are typically measured in IUs, or international units, instead of milligrams or micrograms.
Vitamin EWhat it does for you: This vitamin's major function is as an antioxidant. Recent studies point to positive effects on eye health and the prevention of Alzheimer's disease.
How much you need daily: Generally, 22.5 IUs. There is controversy about safe upper limits, but most agree that adding 150 to 200 IUs shouldn’t hurt and might help.
Best food sources: Avocados, vegetable oil (such as safflower, sunflower, cottonseed, canola, and olive), wheat germ, sunflower seeds, almonds, and most other nuts.
How to eat enough of it: It's easy to meet the RDA with food―one cup of raw broccoli plus two ounces of either almonds or sunflower seeds will do it.
What it does for you: Low intake during pregnancy causes a higher-than-normal risk of neural-tube birth defects, such as spina bifida. Deficiencies may be a risk factor for some cancers, heart disease, and stroke.
Folic Acid (Folate)
How much you need daily: Generally, 400 micrograms.
Best food sources: Leafy vegetables, strawberries, wheat germ, broccoli, asparagus, whole grains, beans, and foods that have been fortified with folic acid, such as cereals and breads.
How to eat enough of it: A 3/4-cup serving of fortified breakfast cereal contains 100 percent of what you need. A cup of peas, a cup of cooked spinach, and about five spears of asparagus also add up to the RDA.
IronWhat it does for you: It prevents iron-deficiency anemia. There's also evidence that it helps support a healthy immune system. A deficiency may be linked to impaired memory and an inability to focus.
How much you need daily: Generally, 18 milligrams. Excess levels of iron are rare but may damage organs, so never supplement iron beyond the amount found in most multivitamins without a doctor's prescription.
Best food sources: Iron is most plentiful in and best absorbed from red meat, clams, and, in lesser amounts, egg yolks, chicken, and fish. It’s also found in legumes, fortified grains, and cereals.
How to eat enough of it: A large spinach salad, a cup of lentil soup, and a small (three-ounce) serving of red meat will give you adequate iron.
What it does for you: It helps maintain healthy blood clotting and promotes bone density and strength.
How much you need daily: No RDA has been set. The adequate intake (AI) for women is 90 micrograms.
Best food sources: Dark green, leafy vegetables and vegetable oils, such as olive, canola, and soybean.
How to eat enough of it: One cup of raw broccoli or a spinach salad will provide about all you need.
MagnesiumWhat it does for you: It helps maintain normal muscle and nerve function, regulate blood sugar levels, and keep bones strong. A lack of it in your diet may contribute to heart disease or high blood pressure.
How much you need daily: Generally, 320 milligrams.
Best food sources: Whole-grain breads and cereals, legumes, spinach, broccoli, dates, raisins, bananas, almonds, cashews, peanuts, walnuts, and pecans.
How to eat enough of it: Have two slices of whole-wheat toast for breakfast, snack on three ounces of almonds and raisins in the afternoon, and for dinner try three ounces of grilled halibut with a baked potato.
What it does for you: It plays an important role in supporting a healthy immune system. Sucking on zinc lozenges several times a day during the first few days of a cold may shorten its duration and lessen the severity of symptoms.
How much you need daily: The RDA for women is eight milligrams.
Best food sources: Animal products, like beef shank and pork tenderloin, as well as oysters and nuts.
How to eat enough of it: A cheeseburger on a whole-wheat bun will get you to the RDA.