Calcium

How much do you need? Men to age 70: 1000 mg (then 1200 at 71+). Women, 1200 mg starting at age 51

Why you need it: Calcium helps form and maintain healthy teeth and bones; needed for normal heartbeat; helps with blood clotting.

Good to know: The body needs vitamin D to help absorb calcium, so if you use calcium supplements choose one that contains D. Recent studies have linked calcium pills to increased risk of heart attack.

Food sources: Dairy products, green leafy vegetables, bok choy, calcium-fortified orange juice.

Chromium

How much do you need? Men: 30 mcg. Women: 20 mcg

Why you need it: Chromium helps maintain normal blood sugar levels.

Good to know: There has been interest in treating high glucose levels and type 2 diabetes with supplemental chromium, but research to date is inconclusive.

Food sources: Meat, chicken, broccoli, apples, fish, grape juice.

Iodine

How much do you need? Men and women: 150 mcg

Why you need it: Dietary iodine is necessary for normal thyroid function; prevents goiter, a swelling of the thyroid gland.

Good to know: Deficiency occurs more often in women than men; when buying salt, choose one labeled "iodized."

Food sources: Seafood, iodized salt.

Iron

How much do you need? Men and women: 8 mg

Why you need it: Dietary iron is essential for healthy red blood cells.

Good to know: Men and women over 50 generally should not take a mutivitamin containing iron unless they have been diagnosed with iron deficiency.

Food sources: Meat, eggs, fortified bread and grain products.

Magnesium

How much do you need? Men: 420 mg. Women: 320 mg

Why you need it: Magnesium supports a healthy immune system; helps keep bones strong; regulates heart rhythm.

Good to know: Magnesium-rich foods may help protect against the development of type 2 diabetes; may also decrease the risk of high blood pressure in women.

Food sources: Whole grains, nuts, green vegetables.

Potassium

How much do you need? Men and women: 4700 mg

Why you need it: Potassium is crucial for heart, kidney, muscle, nerve function; important in controlling blood pressure; works with sodium to maintain the body's water balance.

Good to know: With age, kidneys become less able to remove potassium from blood, so speak with your doctor before taking supplements. A diet rich in fruits and vegetables generally provides sufficient potassium.

Food sources: Cantaloupe, bananas, yogurt, leafy green vegetables and sweet potatoes.

Selenium

How much do you need? Men and women: 55 mcg

Why you need it: Selenium helps make special proteins that play a role in preventing cell damage.

Good to know: May reduce the risk of certain cancers, including lung, colorectal and prostate, although not all studies have found this effect.

Food sources: Red meat, fish, chicken, vegetables.

Zinc

How much do you need? Men: 11 mg. Women: 8 mg

Why you need it: Aids in wound healing; keeps sense of smell and taste sharp.

Good to know: Many people take zinc to ease the miseries of a common cold, but its effect is controversial; some studies suggest zinc can speed recovery, others conclude it doesn't work. Some studies show that taking a combination of antioxidants and zinc reduces the risk of advanced age-related macular degeneration.

Food sources: Fortified cereals, red meat, eggs, seafood.

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