Monday, March 24, 2008

A Look at Minerals and RDAs

"Manganese is very important for people with anemia (iron deficiency) and is needed for the processing of vitamin B1 (thiamine) and vitamin E."

Everybody knows that adequate vitamins and minerals are necessary for life. Few people, however, know exactly what those nutrients do for the body. Here's a summary.

The RDAs (Recommended Daily Allowances) of nutrients are calculated based on age and gender, so be sure to verify those numbers for yourself.

Calcium

The most plentiful mineral found in the human body, calcium accounts for 1.5 to two percent of an adult's total body weight. The teeth and the bones contain the majority of the body's calcium (about 99 percent). Body tissues, blood and other body fluids contain the remaining calcium (one percent).

Many foods contain calcium, but dairy products are the most significant source. Milk and dairy products such as yogurt, cheese and buttermilk contain a more efficiently absorbed form of calcium. Green leafy vegetables such as broccoli, collards, kale, mustard greens, turnip greens, and bok choy or Chinese cabbage are good sources of calcium. Calcium is one of the most important minerals for the growth, maintenance and reproduction of the human body.

The USRDA for calcium is 1,000 milligrams for men and 1,200 milligrams for women.

Iron

Iron is the mineral that occurs in the greatest amount in the blood. The most important function of iron in the human body is helping the production of both hemoglobin and myoglobin. Myoglobin is a form of hemoglobin found in muscles.

Iron is also involved in the oxygenation of your body's red blood cells. This mineral is also needed for energy production and a healthy, strong immune system. The best food sources of easily absorbed iron are animal products. Iron from vegetables, fruits, grains and supplements are harder for the body to absorb. If you mix lean meat, fish or poultry with beans or dark leafy greens at a meal, you can improve absorption of vegetable sources of iron up to three times.

The USRDA for iron is 10 milligrams for men, 15 for women. Women's iron needs may increase to as much as 30 milligrams/day during pregnancy.

Magnesium

Magnesium is one of the body's major electrolytes, essential for metabolism, and an aid to the growth of bone as well as nerve and muscle health. Magnesium has several important metabolic functions. It plays a role in the production and transport of energy. It is important in the contraction and relaxation of muscles.

Most dietary magnesium comes from vegetables, particularly dark-green leafy vegetables. Other foods that are good sources of magnesium are soy products such as soy flour and tofu; legumes and seeds; nuts such as almonds, Brazil nuts, pecans and cashews; whole grains such as brown rice and millet; and fruits such as dried apricots and avocado.

The USRDA for magnesium is 420 milligrams for adult males, 320 for adult females. Please note that the FDA updated the RDAs in 1997, and these numbers reflect the most recently established RDA.

Phosphorus

Phosphorus helps your body process vitamins and aids in the conversion of food into energy. A proper balance of calcium, magnesium and phosphorus is required every day. If any of these minerals are overabundant or deficiently in the body, there can be adverse effects.

The main food sources are the protein food groups of meat and milk. A meal plan that provides adequate amounts of calcium and protein also provides an adequate amount of phosphorus. Whole-grain breads and cereals contain more phosphorus than refined cereals and breads made from refined flour. The main function of phosphorus is in the formation of the bones and teeth.

The USRDA for phosphorus is the same for men and women: 700 milligrams.

Potassium

Potassium is important to your body for a strong, healthy nervous system, maintaining a regular heart beat and proper muscle contraction. Potassium nourishes the heart, kidneys, pancreas, muscles and the nerves. Fish such as salmon, cod, flounder and sardines are good sources of potassium. Various other types of meats also contain potassium. Vegetables including broccoli, peas, lima beans, tomatoes, potatoes (especially their skins) and leafy green vegetables such as spinach, lettuce and parsley contain potassium.

Both men and women need 2,000 milligrams of potassium daily.

Sodium

The right amount of sodium is required by the body to regulate blood pressure and blood volume. Sodium also assists in the proper functioning of muscles and nerves. Sodium occurs naturally in most foods. For example: milk, beets and celery have sodium. It is also present in drinking water; the amount varies depending on the source of the drinking water. Processed meats, such as bacon, sausage and ham, and canned soups and vegetables are all examples of foods that contain added sodium. Fast foods are generally very high in sodium.

Excessive dietary sodium has been linked to cardiovascular disease, so it is important to limit your daily intake to the RDA for sodium, which is 500 milligrams.

Zinc

Zinc is an important trace mineral. It is second only to iron in its concentration in the body. Zinc plays an important role in the proper functioning of the immune system in the body. It is required for the enzyme activities necessary for cell division, cell growth and wound healing. High-protein foods contain high amounts of zinc. Beef, pork and lamb contain more zinc than fish. The dark meat of a chicken has more zinc than the light meat. Other good sources of zinc are peanuts, peanut butter and legumes.

Men need 15 milligrams per day, women, only 12.

Copper

Copper, along with iron, helps in the formation of red blood cells. It also helps to keep the blood vessels, nerves, immune system and bones healthy. Oysters and other shellfish, whole grains, beans, nuts, potatoes and organ meats are good sources of copper. Dark, leafy greens, dried fruits such as prunes, cocoa, black pepper and yeast are also sources of copper in the diet.

Both men and women require 1.5 to 3 milligrams of copper daily.

Manganese

Manganese is needed in small amounts for your body's fat and protein metabolism. It is used in energy production. Manganese is essential for a healthy immune system, healthy nerves, normal bone growth, blood sugar regulation and reproduction. Manganese is very important for people with anemia (iron deficiency) and is needed for the processing of vitamin B1 (thiamine) and vitamin E. Manganese helps in the formation of mothers' milk and is a key mineral in the production of enzymes needed to oxidize fats.

Both men and women need 2 to 5 milligrams of manganese a day.

Selenium

Selenium is an essential trace element. It is an integral part of enzymes. Fish, shellfish, red meat, grains, eggs, chicken, liver and garlic are all good sources of selenium. The amount of selenium in vegetables is dependent on the selenium content of the soil. Brewer's yeast and wheat germ, both considered "health foods," are also good sources of selenium.

Men need 70 micrograms (ug) and women need 55 micrograms of selenium daily.

Chromium

Chromium is important in the metabolism of fats and carbohydrates. Chromium stimulates fatty acid and cholesterol synthesis, and is an activator of several enzymes. Sources of chromium are beef, liver, eggs, chicken, oysters, wheat germ, green peppers, apples, bananas, spinach and butter. Black pepper and molasses are also good sources of chromium, but they are normally consumed only in small amounts.

Both men and women require 50 to 200 micrograms (ug) of chromium daily.

Molybdenum

Molybdenum is a mineral essential to daily functioning. Molybdenum facilitates the metalloenzymes (an enzyme consisting of a protein linked with a specific metal) of many bodily processes. It is needed in such miniscule amounts that there has been no documented case of deficiency. A standard diet usually supplies adequate intake. Legumes, breads, grains, leafy green vegetables, milk and liver are all good sources of molybdenum. Both men and women need 75 to 250 micrograms (ug) of molybdenum daily, which represents approximately 0.1 parts per million parts of body tissue. A standard diet usually supplies adequate intake. Legumes, breads, grains, leafy green vegetables, milk and liver are all good sources of molybdenum.

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