Dietary minerals

Minerals are chemical elements needed for a variety of important physiological processes. For example, they regulate fluid balance, muscle contractions and nerve impulses. Major minerals, such as calcium, phosphorus and magnesium, are needed in large quantities. Sodium, chloride and potassium are three electrolytes (substances that can transmit electrical impulses when dissolved in body fluids) that are also classified as major minerals. Trace minerals, such as chromium, copper, fluoride, iodine, iron, selenium and zinc, are needed in much smaller quantities. By eating a well-balanced diet that incorporates many different foods, you should be able to meet your body's requirements for both types of minerals.


General information
All minerals are absorbed in the intestines. From there, they're transported to different places in the body, such as the bloodstream, muscles or other body tissues. Normally, the body regulates itself and keeps mineral stores in balance. Mineral stores can become unbalanced for many reasons, however.
Sometimes, taking certain drugs can cause problems. For example, diuretics used to ease fluid retention can reduce levels of potassium, which is required for proper muscle functioning. Loss of body fluids through excessive perspiration or diarrhea can also deplete mineral reserves and cause imbalances. In such cases, your body may adjust by absorbing more minerals from the food you eat or what you drink. If the mineral loss is severe, medical intervention may be required. For example, if you take diuretics, you may need to take a potassium supplement.

Although the body can usually eliminate unnecessary minerals, mineral reserves may sometimes get too high. For example, fluoride can cause headaches, nausea and vomiting if taken in too large a dose, and large doses of iron are potentially life-threatening. Small children may develop fluoride poisoning by eating large amounts of toothpaste. In other cases, certain medical conditions may cause mineral reserves to become toxic. For example, Wilson's disease, an inherited condition that affects copper metabolism, can lead to potentially fatal levels of copper if left untreated.

Dietary deficiency of minerals such as calcium, magnesium and potassium may play a role in the development of high blood pressure.


Nutrition terminology
Trying to make sense of your nutrition requirements can be confusing and sometimes even overwhelming. Here are definitions of some of the most common nutrition terms you may encounter:
Recommended dietary allowance (RDA) is the recommended daily amount of a nutrient most people need to stay healthy. These recommendations were developed by the Food and Nutrition Board of the National Academy of Sciences. They were last revised in 1989.

Adequte intake (AI) is the recommended daily amount of a nutrient needed when an RDA cannot be determined.

Tolerable upper intake level (UL) is the maximum daily amount of a nutrient that is not likely to have harmful health effects for people in the general population.

Dietary reference intake (DRI) is the term used for a set of nutrient reference values. These values include the RDA, AI and UL nutrient recommendations. Many nutrient requirements have been updated since the RDAs were originally set. The DRIs were developed in 2000.

Many conditions can affect your daily nutritional requirements, including your age, health status, weight and sex. Women who are pregnant or nursing may have enhanced nutritional needs. Your lifestyle habits, such as smoking or drinking excessive amounts of alcohol, can also have an impact on your nutritional needs. Consult your doctor about health factors that may affect your nutritional needs. Discuss your child's nutritional needs with his or her doctor.


Calcium
Calcium is essential for building strong bones and teeth, as well as maintaining bone strength and density. Calcium also plays a role in muscle contraction, blood clotting and maintenance of cell membranes. To absorb calcium, your body needs plenty of vitamin D. You can get vitamin D through a healthful diet and exposure to the sun's ultraviolet rays. Children and adolescents often lack calcium in their diets, which may lead to osteoporosis as an adult.
Good sources of calcium include:

milk and milk products
tofu processed with calcium
dark green leafy vegetables, such as kale, turnip and mustard greens
broccoli
canned salmon with bones
juices and other foods fortified with calcium
The daily adequate intake (AI) for calcium is:

1,000 milligrams for people ages 19 to 50
1,200 milligrams for people age 51 and older
Some authorities recommend the following calcium intake for the treatment of osteoporosis:

1,500 milligrams for men and women over age 65 and postmenopausal women not taking estrogen
1,000 milligrams for postmenopausal women taking estrogen replacement therapy
1,000 milligrams for men under age 65
Keep in mind that excessive amounts of calcium (2,000 milligrams or more per day) may decrease the absorption of the minerals iron, zinc and manganese, as well as increase the chance of developing kidney stones.


Magnesium
Magnesium is a component of bones. It helps maintain the enzymes used for muscle contraction, energy and protein production, as well as the cells found in nerve and muscle tissue. It also helps regulate blood pressure and prevent tooth decay. Magnesium deficiencies are rare but may occur if you have a kidney disease, intestinal malabsorption or other condition that prevents your body from absorbing magnesium properly. Researchers suspect a magnesium deficiency may also play a role in the development of osteoporosis, although further study is needed.
Most dietary magnesium comes from green vegetables, beans, whole grains and and nuts. If you have hard water (which contains a variety of dissolved minerals), magnesium in the water may contribute to your dietary intake.

The daily RDA for magnesium is:

400 milligrams for men ages 19 to 30
420 milligrams for men age 31 and older
310 milligrams for women ages 19 to 30
320 milligrams for women age 31 and older

Phosphorus
Phosphorus is another key element for building strong bones and teeth. Phosphorus also helps the body release energy from fat, protein and carbohydrates during metabolism. Finally, the mineral plays a role in the formation of genetic material, cell membranes and certain enzymes. Although uncommon, phosphorus deficiencies may develop in premature infants who are breastfed, people who have an extreme lack of protein in their diets, people with alcoholism, or those who take antacids that contain aluminum hydroxide (which binds phosphorus) for a long time.
Good sources of phosphorus include:

meat, fish and poultry
eggs
dairy products
lentils, peas, lima beans and dried beans
grain products
The daily RDA for phosphorus is 700 milligrams for adults. It's possible to get too much phosphorus by drinking very large amounts of soda.


Potassium
Potassium is an important mineral for the heart and other muscles. It helps muscle contraction and maintains fluid and electrolyte balances in the body. The mineral also helps transmit nerve impulses and release energy from fat, protein and carbohydrates during metabolism.
Most potassium deficiencies are caused by excessive loss of potassium, rather than diet. This may occur with severe vomiting or diarrhea or with prolonged use of certain medications, such as some diuretics or laxatives. Symptoms of potassium deficiency may include muscle weakness, fatigue, nausea or confusion. Excessive potassium supplementation can cause heart problems or symptoms such as muscle weakness or vomiting.

Good sources of potassium include:

dried fruits, such as apricots, raisins and prunes
bananas, cantaloupe, grapefruit and orange juice
tomatoes
potatoes
fish and poultry
dry beans, peas and lentils
milk and yogurt
Although there is no established recommended daily allowance for potassium, 2,000 milligrams a day is considered sufficient.


Sodium and chloride
Sodium is found in your body and the foods you eat. Manufacturers often use sodium when processing foods. At home, you probably use salt, which is a combination of sodium and chloride. Your body uses sodium to produce muscle contractions, maintain fluid balance, conduct nerve impulses, and carry nutrients to cells. Sodium is essential, but you don't need much to survive. Most people need about 500 milligrams of sodium a day to ensure good health -- the amount found in just ¼ teaspoon of salt. If you eat a lot of processed foods, your sodium intake may be as high as 4,000 to 6,000 milligrams per day. Chloride also helps maintain fluid balance and is a major component of natural stomach acid, which helps your body digest protein and absorb iron. Although there's no established recommended daily allowance for chloride, 750 milligrams a day (the amount in ¼ teaspoon of salt) is considered sufficient.
Problems such as vomiting, diarrhea or prolonged excessive sweating can cause deficiencies in both sodium and chloride. You may experience symptoms such as muscle cramps, fatigue, dizziness and nausea. For some people, too much dietary sodium contributes to high blood pressure.

If you need to reduce the amount of sodium in your diet, avoid the following high-sodium foods:

anchovies, bacon, bologna, cured and canned meats, frankfurters, pastrami, salami, sausage and pepperoni
barbecue sauce, soy sauce and Worcestershire sauce
chips, crackers and salted nuts
olives and pickles
pizza
canned soup and vegetables and packaged soup mixes, unless they're low in sodium
prepackaged convenience or processed products that are high in sodium, such as frozen meals

Zinc
Zinc is elemental to forming protein, which promotes wound healing. Zinc also plays a role in metabolism, immune function, and tissue growth and maintenance. Although most foods don't contain a significant amount of zinc, you can typically get an adequate amount of the mineral by eating a balanced diet. The highest levels of zinc are found in animal foods, including meat and seafood. Whole grains, milk, cheese, dry beans and nuts are also good sources. Plus, most ready-to-eat fortified cereals contain zinc. To prevent losing the mineral through food preparation, cook foods in a minimal amount of water for the shortest time possible.
A zinc deficiency can result in a variety of problems, such as growth retardation, hair loss, dry skin, poor appetite, susceptibility to infections and night blindness. Severe zinc deficiencies are uncommon in the United States. Excessive zinc supplementation can lead to symptoms such as vomiting, diarrhea, muscle pain, drowsiness and headaches.

The daily RDA for zinc is:

11 milligrams for men
8 milligrams for women
The upper daily limit for adults is 40 milligrams.