MINERALS

Minerals are chemical elements that are obtained from the Earth's crust. They are needed in the structure of the body or for the many biochemical processes that sustain life. Minerals can be grouped in two catogeries: the major minerals and the microminerals.

Unlike some of the vitamins, minerals cannot be made in the body and have to be gained from the diet. There is some concern that mineral deficiencies, partly because many of the minerals, normally aborbed by plants from the soil, have not been replaced when chemical fertilizers are applied.

In addition, the distribution of minerals in the Earth's crust is variable, so the soil in some areas can be naturally low in essential minerals.

The Major Minerals
These are the minerals that are found in the greatest amounts in the body, and a number of them contribute to the infrastructure of the body, such as calcium in the bones.

Calcium, Magnesium and Phosphorus
These three minerals act together to maintain healthy bones, relay messages along nerves an enable muscles to function normally. However, they compete with one another for absorption in the intestine.

Phosporus is the most easily absorbed, and can be disproportionately high in a diet that contains too much animal protein or carbonated drinks, such as sodas or cola. Hard water can supply useful amounts of both calcium and magnesium.

Calcium
Additional functions: enables blood to clot; may help to prevent colon cancer and lower blood pressure.
Good sources: milk and milk products, eggs, canned sardines including the bones, beans and green leafy vegetables.
Cautions: a high intake of calcium, when magnesium intake is inadequate, can cause kidney stones. It can also be deposited in soft tissue, such as in muscle and the walls of arteries.

Magnesium
Additional functions: helps to release energy from food; enables muscles to relax, including the muscles of arteries, which help to control blood pressure.
Good sources: pulses, nuts, dark green vegetables, shellfish, eggs, meat, wholemeal bread, blackstrap molasses, walnuts and bananas.

Phosphorus
Additional functions: vital for energy production; helps certain B vitamins to function effectively.
Good sources: cheese, eggs, wholemeal bread, meat, peanuts, prawns, walnuts and yoghurt.
Cautions: excessive phosphorus may be one cause of calcium deficiency and possibly of osteoporosis.

Sodium, Potassium and Chloride
The balance between these three minerals is vital in regulating the amount of water in the body and the delicate balance of its distribution in the tissues and inside the cells. In general, the Western diet contains too much added salt, which consists of sodium and chloride, and this can lead to fluid imbalance. The exchange of sodium and potassium across the walls of cells enables muscles to relax and contract, and messages to be sent along nerve fibres.

Sodium
Good sources: bacon, ham, salted or smoked fish, olives in brine, pretzels and bread.
(Note: when a food label specifies salt, you can calculate the sodium content by dividing the figure given for the amount of salt by 2.5)

Potassium
Additional functions: helps to avoid fatigue and depression; helps to regulate blood pressure.
Good sources: all fruit and vegetables, nuts, pumpkin seeds, meat and molasses. Salt substitute contains potassium chloride.

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Chloride
Additional functions: essential for the hydrochloric acid secreted by the stomach for digestion.
Good sources: food to which salt or salt substitute has been added, such as tomato juice and celery.

Silicon
Needed for: strong but supple bones, arteries, cartilage and tendons; may help prevent osteoporosis, osteoarthritis, high blood pressure and Alzheimer's disease.
Good sources: hard water, unrefined grains, root vegetables, onions and sprouts.

Sulphur
Needed for: healthy skin, hair and immune system.
Good sources: protein food, especially egg yolks, garlic, onion and vegetables of the brassica family, such as broccoli, cabbage and Brussels sprouts.

The Microminerals
These minerals are found in small amounts in the body. Many of them are an essential part of one or more enzymes, which are protein that act as catalysts for the normal biochemical activity of the body.

Boron
Needed for: healthy bones; normal brain function.
Good sources: non-citrus fruit, leafy vegetables, nuts and pulses.

Chromium
Needed for: stabilizing blood sugar levels, lowering cholesterol and maintaining optimum body weight.
Good sources: brewer's yeast, molasses, whole grains and vegetables.

Copper
Needed for: production of blood cells and as part of the body's protection against free radicals.
Good sources: shellfish, liver, brewer's yeast , olives, wholemeal flour, walnuts, peanuts and avocados.
Cautions: high doses can depress zinc levels; can be toxic in high doses.

Iodine
Needed for: thyroid hormones, which regulate energy production.
Good sources: fish, seaweed such as kelp, sea salt, milk and eggs when iodine is fed to farm animals.

Iron
Needed for: distributing oxygen in the blood to all parts of the body.
Good sources: red meat, liver, wholemeal bread, fortified breakfast cereals, soy sauce, watercress and green vegetables. Absorbed best when food containing vitamin C are eaten at the same time.
Cautions: men and postmenopausal women should take iron supplements with caution. Iron can accumulate in the tissues and may predispose them to heart disease.

Manganese
Needed for: healthy bones and cartilage.
Good sources: whole grains, nuts, meat, dairy products, black tea and ginger.

Molybdenum
Needed for: its contribution to the body's protection against free radicals.
Good sources: milk and milk products, pulses, offal (liver and kidney).

Selenium
Needed for: its powerful antioxidant function.
Good sources: Brazil nuts, shellfish, molasses, eggs, milk and whole grain.
Cautions: can be toxic in high doses.

Zinc
Needed for: healthy immune system: normal sexual function in men.
Good sources: meat, eggs, fish, wholemeal bread, Brazil nuts, sesame seeds and brewer's yeast.
Cautions: high doses can depress copper levels; can be toxic in high doses.

Taking mineral and vitamin supplements should be regarded as a health insurance policy to complement a healthy diet.