Vitamins and Minerals

Minerals

Although vitamins generally receive more attention than minerals, the body actually needs larger amounts of certain minerals—called macrominerals—than the amounts of vitamins it requires to stay healthy. The seven macrominerals, all required in amounts of 100 mg or more a day, are calcium, magnesium, phosphorus, sodium, potassium, chloride, and sulfur. In addition, there are 10 microminerals, also called "trace elements," of which the body requires only very small amounts. These are cobalt, iron, zinc, iodine, copper, fluorine, manganese, chromium, selenium, and molybdenum. In spite of the small requirements for these minerals—in some cases considerably less than 1 mg—they are all needed if good health is to be maintained.

Iron, which plays an important role in carrying oxygen to the tissues, has long been the mineral best known to the general public because of its connection with anemia. Iron-fortified, multivitamin supplements have been popular for decades. Women are especially at risk for iron deficiency because iron is lost during menstruation, especially by women who bleed heavily. Good dietary sources of iron are red meat, liver, dark green leafy vegetables, and legumes. In addition, many foods are fortified with iron.

Calcium, which is necessary for healthy bones and teeth, is the body's most plentiful mineral, accounting for about 2% of the average person's body weight. This mineral is also needed for muscle contraction, blood clotting, and the release of neurotransmitters, which carry impulses throughout the nervous system. The main dietary sources of calcium are dairy products. Other good sources of calcium are green leafy vegetables, beans, and nuts. Many foods, including orange juice, breakfast cereal, and bread, are available fortified with calcium.

Zinc is an important mineral found in all the cells of the body. It is necessary for normal physical growth in children and is also known for promoting healing and fighting infections. Zinc deficiencies in pregnant women can interfere with normal fetal development. Animal products—especially meat and seafood—are the main dietary source of zinc. Magnesium, which activates over 300 of the body's enzymes, is needed for muscle relaxation. It is thought to reduce hypertension and lessen the damage from heart attacks. Selenium, another important mineral, is an antioxidant believed capable of preventing heart attacks and reducing the risk of certain types of cancer.