Healthy Eating: Mighty Minerals
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Minerals that are needed in smaller amounts than the major minerals are referred to as trace minerals or trace elements. Even though our bodies require only a small amount of these minerals, they are still very important to proper health. Most trace minerals are needed in amounts of less than 20 mg per day.
Other trace minerals include arsenic, silicon, vanadium, nickel, and boron. Little is known about these trace elements and their role in human health. In fact, there are no RDAs, DRIs, or safe and adequate ranges set for these minerals, because not enough is known about what the body requires for proper health and functioning. A healthy, varied, and balanced diet is the best way to ensure you consume safe and adequate amounts of these other trace minerals.
Almost every cell in the body contains zinc, and it is also part of over 70 different types of enzymes. Zinc is known as the second most abundant trace mineral in the body. It is essential for normal growth and development and is vital to a healthy immune system. Zinc assists the body in using the macronutrients (carbohydrates, proteins, and fats). In addition, zinc functions in the production of proteins, proper functioning of the hormone insulin, the maintenance of your genetic code, and normal taste.
Is it helpful to take over-the-counter zinc lozenges when you feel the symptoms of a cold coming on? Scientists have found that in test tubes, zinc can prevent cold viruses from reproducing themselves. But as for its ability to fight the disease in the human body, the jury is still out. Some studies have shown that if zinc lozenges are taken within twenty-four hours of coming down with cold symptoms, they may help shorten the length of the cold.
Adequate levels of zinc are vital to good health because zinc is involved in so many enzyme and body functions. A deficiency of zinc in childhood can cause retarded growth; deficiency during pregnancy can cause birth defects. Other deficiency symptoms include loss of appetite, skin changes, and reduced resistance to infection. Too much zinc, especially from supplements, can trigger harmful side effects that include impaired copper absorption. The UL for zinc is 40 mg per day for adults over eighteen years of age.
Good food sources of zinc include animal foods such as meat, seafood, and liver. Milk and eggs supply a little less zinc. Foods such as whole-grain products, wheat germ, legumes, nuts, and seeds have a good concentration of zinc; however, the zinc that plant foods provide is less available to the body.
Iodine is a component of the thyroid hormone called thyroxin. Thyroxin regulates the rate at which the body burns calories or uses energy from food. With a deficiency of iodine, the body cannot make sufficient amounts of thyroxin. As a result, the rate at which the body burns calories slows down. A deficiency can be especially harmful in pregnant women, the developing fetus, and the newborn. Poor iodine intake is associated with hypothyroidism and/or the development of an enlarged thyroid gland, commonly called a goiter. Too much iodine can also cause the development of a goiter, but this is not common at the levels that are consumed on average in the United States. Iodine has a UL set at 1,100 mcg per day for adults over eighteen.
Iodine is found naturally in saltwater fish and seafood such as seaweeds. Most of the iodine in the United States is ingested through the form of iodized salt.
Selenium works with vitamin E as an antioxidant. Together they help protect cells from damaging free radicals that may lead to health problems such as cancer and heart disease. Selenium is also important in cell growth.
A severe deficiency, although extremely rare, is associated with a severe heart disorder. The body requires only a small amount of selenium. Too much selenium over prolonged periods of time can produce signs of toxicity that can be harmful. Selenium has a UL set at 400 mcg per day for adults over eighteen. A normal healthy diet with a variety of foods generally provides the selenium required for normal body function. Food sources of selenium include seafood, liver, and kidney, as well as other meats. Many plant foods contain selenium, such as grain products and seeds, but the amount is directly related to the level of selenium in the soil that produces the food. Most fruits and vegetables don't contain much selenium.
Copper is found in all the tissues in the body, but is concentrated in the brain, heart, kidney, and liver. Copper is the third most abundant essential trace mineral, after iron and zinc. Copper helps the body make hemoglobin (needed to carry oxygen to red blood cells) and red blood cells by aiding in the absorption of iron in the body. Copper is part of many enzymes in the body and helps produce energy in cells. In addition, copper helps make hormones that regulate a variety of body functions, including heartbeat, blood pressure, and wound healing.
Fact: A copper deficiency can cause iron deficiency, since copper is required for proper iron absorption and utilization.
Copper deficiency rarely comes from the diet. Most deficiencies are due to a genetic problem or from too much zinc. Copper toxicity is rare. High daily intakes can cause nausea and vomiting. Copper has a UL set at 10,000 mcg per day for adults over eighteen.
Copper is found mostly in organ meats, especially liver, and in seafood, nuts, and seeds. It can also be found in poultry, legumes, and dark green leafy vegetables. Cooking in copper pots increases the copper content of foods.
Manganese serves as part of many types of enzymes, including enzymes involved in blood sugar control, energy metabolism, and thyroid hormone function. Manganese is widely distributed in food, so deficiencies are very rare. Deficiencies could be associated with impaired fertility, growth retardation, birth defects, and general weakness. Consuming harmful levels of manganese is also rare. Too much, though, could inhibit the absorption of iron, copper, and zinc. Manganese has a UL set at 11 mg per day for adults over eighteen. Manganese is found mostly in whole-grain foods, along with some fruits and vegetables.
More on: Nutritional Resources for Families
Copyright © 2002 by Kimberly A. Tessmer. Excerpted from The Everything Nutrition Book: Boost Energy, Prevent Illness, and Live Longer with permission of its publisher, Adams Media Corporation.
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