Food Nutrients - Minerals

A large number of minerals are present in the body. Some of these form part of body structural components and some others act as catalytic agents in many body reactions.

• Calcium
• Phosphorus
• Iron
• Sodium
• Potassium

Calcium:

What is it?
Calcium is an element found in bones, shells and limestone, among other materials.
What does it do?
Calcium, along with vitamin D, helps build and maintain healthy bones and teeth. In addition, calcium:

• helps lower blood pressure and control heartbeat
• helps regulate muscle contractions
• plays a role in blood clotting
• prevents fatal bleeding from breaks in the walls of blood vessels
• maintains cell membranes
• aids in the absorption of vitamin B12
• activates enzymes such as lipase, the fat-splitting enzyme

Your bones furnish reserves of calcium to keep plasma constant at all times.
Where do we get it?
Dairy products are the preferred sources of calcium. Children need 3 servings a day whereas pre-teens, teens and older adults need four servings a day. The following foods provide about 400 milligrams of calcium:

• Sardines with bones -- 3 1/2 ounces
• Yogurt, plain low-fat with milk solids added -- 1 cup
• Yogurt, plain nonfat -- 1 cup
• Tofu processed with calcium salts (content of tofu varies widely so consult label)
• Cafe latte -- 12 ounces

300 milligrams of calcium:

• Milk -- 1 cup, any kind
• Yogurt -- 1 cup
• Cheese -- 1 1/2 to 2 ounces
• Part-skim ricotta cheese -- 1/2 cup
• Salmon, canned with bones -- 6 ounces
• Collard greens -- 1 cup cooked frozen
• Soy milk -- 1 cup, varies with brand
• Fortified orange juice -- 1 cup

200 milligrams of calcium:

• Cheese -- 1 ounce (cheddar, part skim mozzarella, provolone, process American or swiss)
• Ice cream or ice milk -- 1 cup
• Turnip greens or kale -- 1 cup cooked
• Cheese pizza -- one slice

100 milligrams of calcium:

• Cottage cheese -- 3/4 cup low-fat or creamed
• Broccoli -- 1 cup cooked, frozen
• Navy or pinto beans -- 1 cup cooked
• Taco -- one small
• English muffin -- 1
• Almonds -- 1/3 cup
• Figs, dried -- 4
• Frozen yogurt -- 1/2 cup

50 milligrams of calcium:

• Black beans or lima beans -- 1 cup cooked
• Clams,canned -- 2 ounces
• Shrimp -- 3 ounces canned or 4 1/2 ounces fresh, steamed
• Hamburger bun -- 1
• Orange -- 1

How much do we need?
Most adults need 1,000 milligrams a day; adults over 50 need 1,200 milligrams. Children and adolescents need 1,300 milligrams to build and grow strong bones and calcium stores. Pregnant and breast-feeding women need only the amount recommended for their age. Most Americans do not get enough calcium in their diets, especially women. When calculating the amount of calcium you get in your diet, keep in mind that certain dietary factors, lifestyle characteristics, medical conditions and medications can affect the absorption or excretion of calcium in your body. For example:

• Calcium from foods rich in oxalates (such as spinach, sweet potatoes and beans) or in phytates (such as whole wheat bran, beans, nuts and soy isolates) may be absorbed poorly.
• Protein and sodium in foods boost the amount of calcium excreted in urine, while phosphorus an vitamin D reduce the amount excreted in urine.
• Caffeine reduces the absorption of calcium.
• Cigarette smoking may decrease the absorption o calcium.
• Diseases such as hyperthyroidism and diabetes, and medicines such as corticosteroids and glucocorticoids reduce the absorption of calcium, and increase the amount excreted in urine.
• Alcohol in moderation does not appear to adversely affect calcium availability.

If you are not getting enough calcium in your diet, you should take a supplement. They do not provide the same overall nutrient benefits as foods, however. If you do take calcium supplements, follow these guidelines.

• If you take high amounts, be sure to get at least 18 milligrams of zinc per day, too.
• Avoid supplemental calcium from sources such as dolomite, oyster shell and bonemeal, which may be contaminated with lead or arsenic.
• Take supplements with meals, and spread the daily dosage out over several meals instead of taking it all at once.
• Read labels carefully; not all supplements contain the same amount of calcium. Supplements made from calcium carbonate have the most; 40 percent of the pill is the calcium itself. This number drops to 38 percent for pills made with calcium phosphate, to 21 percent for pills with citrate, and to 13 percent for lactate and 9 percent for gluconate. So you would have to make many more calcium lactate pills than calcium carbonate pills to get the same amount of calcium.

Is It Safe?
A calcium intake of up to 2,500 milligrams is safe for healthy people.

Phosphorous:

What is it?
Phosphorus is a mineral. It is a major component of bones and teeth and makes up part of DNA and RNA.
What does it do?
Phosphorus serves as the main regulator of energy metabolism in cells, helps the body absorb glucose and transport fatty acids, and is part of the buffer system that helps control the acid-base balance of the body.
Where do you get it?
Almost all foods contain phosphorus, including:

• protein-rich foods like milk, meat, fish, eggs and poultry
• legumes and nuts
• foods with phosphorus-boosting additives, such as baked goods, bread, processed meats and cheeses, and soft drinks

Good Sources of Phosphorus:

How much do we need?
The Recommended Dietary Allowance (RDA) for phosphorus is:

• 700 milligrams a day for adults 19-70 years old
• 1,250 milligrams a day for children 9-18 and women who are pregnant or breast-feeding

Deficiencies of phosphorus are rare. Most men get at least 1,500 milligrams and women get more than 1,000 milligrams a day.
Is it safe?
The phosphorus levels in normal diets are not likely to be harmful. It is possible that excessive amounts may lower the levels of calcium in the blood and cause too much calcium to be lost through urine, especially if the intake of calcium and vitamin D is insufficient or marginal. Bone loss then could result.

What does it do?
Iron is part of haemoglobin, the oxygen-carrying component of the blood. Iron-deficient people get tired easily because their bodies are starved for oxygen. Iron is also part of myoglobin, which helps muscle cells store oxygen. Without enough iron, ATP (the fuel the body runs on) cannot be properly synthesized. As a result, some iron-deficient people become fatigued even when their hemoglobin levels are normal. Although iron is part of the antioxidant enzyme catalase, iron is not generally considered an antioxidant, because too much iron can cause oxidative damage.
Where is it found?
The most absorbable form of iron, called "haeme" iron, is found in oysters, meat, poultry, and fish. Non-haeme iron is also found in these foods, as well as in dried fruit, molasses, leafy green vegetables, wine, and most iron supplements. Acidic foods (such as tomato sauce) cooked in an iron pan can also be a source of dietary iron.
Who is likely to be deficient?
Vegetarians eat less iron than non-vegetarians, and the iron they eat is somewhat less absorbable. As a result, vegetarians are more likely to have reduced iron stores. However, iron deficiency is not usually caused by a lack of iron in the diet alone; an underlying cause, such as iron loss in menstrual blood, often exists.
Pregnant women, marathon runners, people who take aspirin, and those who have parasitic infections, hemorrhoids, ulcers, ulcerative colitis, Crohn’s disease, gastrointestinal cancers, or other conditions that cause blood loss or malabsorption are likely to become deficient.
Individuals who fit into one of these groups, even pregnant women, shouldn’t automatically take iron supplements. Fatigue, the first symptom of iron deficiency, can be caused by many other things. A nutritionally oriented doctor should assess the need for iron supplements, since taking iron when it isn’t needed does no good and may do some harm.
How much is usually taken?
If a nutritionally oriented doctor diagnoses iron deficiency, iron supplementation is essential. A common adult dose is 100 mg per day. When iron deficiency is diagnosed, the doctor must also determine the cause. Usually it’s not serious (such as normal menstrual blood loss or blood donation). Occasionally, however, iron deficiency signals ulcers or even colon cancer. Many premenopausal women become marginally iron deficient unless they supplement with iron. Even so, the 18 mg of iron present in most multiple-vitamin/mineral supplements is often adequate.
Are there any side effects or interactions? Huge overdoses can be fatal. Supplemental amounts required to overcome iron deficiency can cause constipation. Sometimes switching the form of iron, getting more exercise, or treating the constipation with fiber and fluids is helpful. Sometimes the amount of iron must be reduced if constipation occurs. Caffeine, high-fiber foods, and calcium supplements reduce iron absorption. Vitamin C slightly increases iron absorption. Taking vitamin A with iron helps treat iron deficiency, since vitamin A helps the body use iron stored in the liver.

Potassium (K):

What is it?
Potassium is a trace mineral essential for growth and good health.
What does it do?
Potassium in the human body helps to:

• keep normal water balance between the cells and body fluids
• maintain normal blood pressure
• transmit nerve impulses
• enable the contraction of muscles
• ensure proper functioning of cellular enzymes

Where do you get it?
Potassium is found in a variety of types of foods, including fruits and vegetables, dairy products, meat and legumes.
Potassium Content of Foods:

By eating five to nine servings of fruits and vegetables per day, you can get enough potassium to help lower your blood pressure and decrease your risk of cancer.
How much do we need?
There is no Recommended Dietary Allowance (RDA) for potassium. The minimum amount per day for adults is 2,000 milligrams, although many experts advise that a better minimum level would be around 3,500 milligrams. A low intake is defined as about 2,500 milligrams a day or less, while 4,000 to 4,500 milligrams a day is considered to be high. The typical U.S. diet provides about 2,000 to 3,000 milligrams a day.
Deficiencies of potassium are rare, but they can occur under the following conditions:

• starvation dieting
• prolonged vomiting or diarrhea
• laxative abuse
• severe burns
• kidney problems

Supplementary potassium may be recommended in certain cases:

• If a potassium deficiency occurs due to increased urinary losses (which are often associated with medications for high blood pressure), a supplemental amount of about 2,000 milligrams a day may be recommended.
• For certain medical conditions, medically supervised use of light salt or salt substitute as a source of potassium may be recommended. One teaspoon of light salt contains 1,500 milligrams of potassium, while salt substitute contains about 2,800 milligrams a teaspoon. For someone without kidney problems, however, fruits and vegetables are far better choices to boost potassium intake.

Potassium in amounts of around 2,300 milligrams a day -- whether from food or supplements -- has been shown to lower blood pressure by relaxing the arteries and reducing blood volumes, especially for people who use a lot of salt. In fact, this amount of potassium lowers blood pressure about half as much as drugs, without the expense or side effects. Potassium is especially effective in diets that also include generous servings of dairy products. The recent DASH (Dietary Approaches to Stop Hypertension) diet recommended 4,700 milligrams of potassium a day.
Is it safe?
Daily consumption of 2,000 to 6,000 milligrams of potassium is a safe range for the general population.