Minerals Health Article

Trace minerals

The trace minerals, or micronutrients, include iron, iodine, zinc, fluoride, selenium, chromium, and copper. Even though these elements are present in very small amounts in the human body, they serve many important functions.

IRON. Iron is a component of hemoglobin in red blood cells and myoglobin in muscle cells. It helps these compounds to hold and carry oxygen throughout the blood and the muscles. Iron also aids in enzyme activity and cell synthesis. Lack of iron in the diet can cause iron-deficiency anemia, which is the most common nutrient deficiency in the world. Symptoms include tiredness, weakness, and a tendency to feel cold. Animal foods such as meat, poultry, and fish are excellent sources of iron. Vitamin C also helps promote the absorption of iron. The RDA of iron is 10 mg for men, 18 mg for women.

IODINE. Iodine is a mineral that is needed for the hormone thyroxine, which plays a part in energy metabolism. Iodine deficiency causes an enlargement of the thyroid gland in the neck, which is known as a goiter. A deficiency in pregnant women can also result in mental and physical retardation known as cretinism. Iodine can be found in seafood, foods grown on land, and bakery products. The RDA of iodine is 150 micrograms.

ZINC. Zinc is needed in only very small amounts, but it functions in nearly every organ of the body. It plays a role in the immune system, sperm production, taste perception, and wound healing. Inadequate intakes of zinc can result in poor growth and appetite as well as poor taste acuity. Too much zinc can impair the absorption of iron and copper in the body. Sources of zinc include meat, shellfish, poultry, legumes, and whole grains. The RDA of zinc is 15 mg.

SELENIUM. Selenium is a relatively rare nonmetallic trace element; there is less than 1 milligram of selenium in the average human body. The selenium is concentrated in the liver, kidneys, and pancreas; and in males, in the testes and seminal vesicles. It also activates thyroid hormone, which regulates the body's metabolism. Selenium can be found in a variety of foods; good sources of it include brewer's yeast, wheat germ, wheat bran, kelp (seaweed), shellfish, brazil nuts, barley, and oats. Selenium is most widely recognized as a substance that speeds up the metabolism of fatty acids and works together with Vitamin E (tocopherol) as an antioxidant. Antioxidants are organic substances that are able to counteract the damage done by oxidation to human tissue. The RDA of selenium is between 0.05 and 0.2 micrograms.

FLUORIDE. Fluoride has not been proven to be an essential mineral, but it does play a role in forming bones and teeth. Fluoride is most readily available from fluoridated drinking water. Too much of this element can cause a discoloration of the teeth known as fluorosis, but adequate fluoride consumption throughout life will help protect against dental caries. The RDA of fluoride is between 1.5 and 4.0 mg.

CHROMIUM. Chromium is closely associated with the hormone insulin, which regulates blood glucose levels. Chromium is usually depleted during food processing, which increases the chance for a deficiency if fast foods are eaten very often. Good sources of chromium include liver, whole grains, cheese, and nuts. The RDA of chromium is between 0.05 and 0.2 mg.

COPPER. Copper helps to form hemoglobin and collagen in the body as well as enzymes. Copper deficiency can impair growth and development, but is rarely encountered. Copper toxicity is also rare, but can occur from too much supplementation. Copper can be found in cherries, legumes, whole grains, seafood, nuts, and organ meats. The RDA of copper is 2–3 mg.

OTHER MICRONUTRIENTS. There are other trace minerals found in the body including boron, molybdenum, cobalt, and nickel. These minerals are all important to the body's health, but they are readily available in a normal diet. Deficiencies of these micronutrients are extremely rare.

KEY TERMS

Acid-base balance—The balance between the acidity and alkalinity of body fluids.

Antioxidant—A substance that works to counteract the damage done by oxidation to human tissue. Dietary antioxidants include the trace mineral selenium.

Electrolyte—An element or compound that dissociates in water and acts as a conductor of electricity.

Hemoglobin—A protein found in red blood cells that carries oxygen from the lungs to the tissues of the body.

Inorganic—Pertaining to chemical compounds that are not hydrocarbons or their derivatives.

Myoglobin—A form of hemoglobin found in muscle tissue.

Trace element—An element that is required in only minute quantities for the maintenance of good health. Trace elements are also called micronutrients.