Part III - Nutritional Review of Minerals

Calcium
Chromium
Copper
Iodine
Iron
Magnesium
Manganese
Molybdenum
Phosphorous
Potassium
Selenium
Silicon
Sodium
Vanadium
Zinc

Calcium
Calcium is the most abundant mineral in the human body. 99% of calcium in the body is found in the bones and teeth. The other 1 percent has biochemical functions in the conduction of nerve impulses, the contraction and relaxation of muscles, in blood clotting, and in regulating the transport of materials into and out of cells. The deposit and re-absorption of the calcium in our bones is a process that continues throughout life. This is why broken bones eventually heal. Therefore calcium is needed in the diet every day. Unfortunately, as we age, the re-absorption of calcium begins to exceed the deposition, and the bones become thinner; osteoporosis can be the eventual result. Although people with certain physical characteristics, especially white women with small bones, are at greatest risk of osteoporosis, the condition is found commonly in people of both sexes and in a great variety of genetic heritages.

Requirements for calcium are large in comparison to most other micronutrients: 800-1500mg daily. The amount varies with age and sex and, for women, increases with pregnancy and lactation. The National Institutes for Health Consensus Panel on Calcium (in the USA) advised that adolescents should consume 1200-1500mg daily. It is possible, though not always each individual's preference, to get the required calcium from dairy products. For many people, supplementation is preferred.

Dietary Sources:
Almonds, Brazil nuts, Caviar, Kelp, Milk, Milk products, Molasses, Salmon (canned), Sardines (canned), Prawns, Soybeans, Tofu, Turnip greens.
RDI: 800-1,000 mg
Toxicity: Healthy adults consuming up to 2,500 mg of calcium per day showed no adverse effects. High intakes of calcium may cause constipation, inhibit the absorption of iron, zinc and other essential minerals, and deterioration in renal function.

Chromium
Chromium is an essential trace mineral, ie; it is required in very small amounts (50-200mcg daily). Chromium works with insulin to maintain normal blood glucose levels. Chromium also influences the metabolism of cholesterol and fat.

Dietary Sources:
Beef, Brewer's yeast, Calves' liver, Chicken, Dairy products, Eggs, Fish and seafood, Fresh fruit, Oysters, Potatoes (with skin), Whole-grain products.
RDI: 120 mcg
Toxicity: Little is known about the toxic effects of large doses of the form of chromium found in food and supplements.

Copper
Although required in small amounts (1.5-3mg daily), copper is involved in numerous important reactions and processes, including several different processes in the utilisation of oxygen. Any reasonably balanced diet contains adequate copper.

Dietary Sources:
Barley, Brazil nuts, Cashew nuts, Hazelnuts (filberts), Honey, Lentils, Molasses (black-strap), Mushrooms, Mussels, Oats, Oysters, Peanuts, Salmon, Walnuts, Wheat germ. RDI: 2 mg
Toxicity: No toxic effects can be expected in humans whose daily copper intake is 500 mcg per 2.21b. (1 kg) of body weight. An occasional intake of up to 10 mg a day is probably safe for adults.

Iodine
Iodine is essential for the synthesis of the thyroid hormones, which are necessary for the regulation of metabolism and growth. Iodine deficiency ceased to be a problem when iodine was added to table salt.

Dietary Sources:
Good sources of iodine include vegetables grown in iodine rich soil, Kelp, Onions, Milk, Milk products, Salt-water fish and Seafood. Sodium or potassium iodide is added to table salt in many countries including Australia.
RDI: 120-150 mcg
Toxicity: Toxicity effects of iodine include a reduction in thyroid hormone secretion, acne, and inflammation of the salivary glands.

Iron
Iron is, extremely important in the transport of oxygen in the blood to the cells. Iron is also found in the muscle protein myoglobin. Because it is so important, iron and it's role in metabolism has been extensively studied, and more information is available from many sources. Adequate iron is usually obtainable from the diet, especially if the diet includes red meat. Many cereals are fortified with iron. Some people prefer to take a supplement. (Vitamin C consumed along with iron increases iron absorption from food and from supplements). For most people, iron absorption is strictly regulated and over absorption is not a potential problem. However, those who carry the rare genetic condition of hemochromatosis are at serious risk of heart conditions resulting from the over absorption of iron.

Dietary Sources:
Bread (enriched), Cashews, Caviar, Cheddar cheese, Egg yolk, Garbanzo beans, Lentils, Molasses (black-strap), Mussels, Pistachios, Pumpkin seeds, Seaweed, Walnuts, Wheat germ, Whole-grain products. Note: Even iron-rich foods are poorly absorbed by humans. Approximately 10% of iron is absorbed from food consumed by an individual with normal iron stores and 20 to 30% is absorbed by an iron deficient person.
RDI: 7-l6mg
Toxicity: Negative effects of daily intakes between 25 and 75 mg are unlikely in healthy persons. Approximately 2,000 cases of iron poisoning, however, occur in the U.S. each year, primarily among young children who ingest iron supplements formulated for adults. The lethal dose of ferrous sulfate for a 2-year-old is approximately 3 g and for adults it ranges from 200 to 250 mg per 1kg of body weight. Some people are genetically at risk from iron overload or hemochromatosis, which results in the failure of multiple organ systems.

Magnesium
Magnesium is a cofactor in over 300 enzymatic reactions in the body. In general, magnesium is required for the metabolism of carbohydrates, proteins and fats, as well as activity related to calcium, phosphorous, and vitamin C. Like iron, its role in health has been extensively studied and information is available from many sources.

Dietary Sources:
Almonds, Bluefish, Carp, Cod, Flounder, Halibut, Herring, Leafy green vegetables, Mackerel, Molasses, Nuts, Ocean perch, Prawns, Snails, Soybeans, Sunflower seeds, Swordfish, Wheat germ.2
RDI: 270-320 mg
Toxicity: There is no evidence to suggest that large oral doses of magnesium are harmful to people, except for people with impaired renal function. Impaired function of the kidneys may result in hypermagnesemia caused by magnesium retention.

Manganese
Manganese has many important functions in metabolism, from formation and maintenance of bone to its role as a cofactor for the antioxidant enzyme superoxide dismutase. More complete information about the metabolic roles of manganese is available from many sources. Manganese is abundantly available in many foods and the small requirement (2-5mg daily) can be met from normal quantities of whole grains, beans, fruit, and shellfish.

Dietary Sources:
Avocados, Barley, Beans (dried), Blackberries, Bran, Buckwheat, Chestnuts, Cloves, Coffee, Ginger, Hazelnuts (filberts), Oatmeal, Peanuts, Peas, Pecans, Seaweed, Spinach.
RDI: 2 mg
Toxicity: In view of the remarkably steady tissue concentrations of manganese in the U.S. population and how low toxicity of dietary manganese, an occasional intake of 10 mg/day by adults can be considered safe.

Molybdenum
Molybdenum is needed to activate certain enzymes. It is required in extremely small quantities (75-250mcg daily), and this requirement is almost always met from food. Overabundance of molybdenum can impair absorption of other minerals, notably copper.

Dietary Sources:
Good sources include Milk, Beans, Bread, Liver and Cereals.
RDI: Recommended Daily Intake has not been set in Australia
Toxicity: These include weight loss, slow growth, anaemia, diarrhoea, and increased levels of uric acid and swelling of the joints.

Phosphorous
Phosphorous, following calcium, is the second most abundant mineral in the human body. Approximately 80 percent of phosphorous are present in the skeleton; the rest is active metabolically.

Phosphorous participates in more biological processes than any other mineral. It is therefore difficult to summarise its activities meaningfully. More information is available from many sources. The daily requirement for phosphorous is quite large (800-1200mg daily, similar to calcium), but this mineral is widely distributed in food. The general population meet their RDI for phosphorous through their diet.

Dietary Sources
These include Meat, Wheatgerm, Poultry, Cheese, Milk, Canned Fish, Nuts and Cereals.
RDI: 1000 mg
Toxicity: High levels of phosphorous can produce calcium deficiency.

Potassium
Potassium is an electrolyte which, together with the other electrolytes sodium and chloride, control the distribution and a balance of water throughout the body. Potassium functions mainly inside cells, and most of the potassium in the body is found in the intracellular fluids. By regulating water balance, potassium helps lower blood pressure. Along with other electrolytes, it helps maintain the acid/alkaline balance throughout the body. Many nutritionists recommend a daily intake of about 3000mg. Although this is a large amount (about two to three times the amount of calcium), potassium is widely available in food and nutritional deficiencies are rare.

Dietary Sources
Foods high in potassium include Fruits, Vegetables and Whole grains.
RDI: 1950-5460 mg
Toxicity: Toxic effects include muscular weakness, ulcers, low blood pressure and, in high enough doses (18, 000 + mg), Coma and death.

Selenium
The role of selenium in metabolism has been under investigation for about 20 years, and there is still much to learn. It is known to be integral to an important antioxidant enzyme found in all cells (glutathione peroxidase), which works synergistically with vitamin E. Selenium is required in small amounts (70mcg daily) and deficiency is rare in areas of the world where the soil is selenium poor. Overabundance of selenium, which may only be the result from supplementation, can cause serious problems.

Dietary Sources:
Organ meats and Seafood.
RDI: 70-85 mcg
Toxicity: Toxic effects include fatigue, hair loss; nail problems, bad breath and nervous system problems.

Silicon
Silicon provides strength, rigidity, and flexibility to bones, teeth, tendons, ligaments, cell membranes, nails and skin. There is some indication that adequate levels of silicon may be associated with decreased risk in the development of atherosclerosis.

Dietary Sources
Silicon is widely available in food. Good sources include Wheat, Oats, Rice, Lettuce, Cucumbers, Avocados and Strawberries.
RDI: Recommended Daily Intake has not been set in Australia
Toxicity: Generally regarded as non-toxic.

Sodium
Sodium is an electrolyte, which, along with chloride and potassium, regulates the fluid balance in the body. Maintaining the correct level of sodium is extremely important in physiology, so the body has many mechanisms to regulate this level, regardless of under or over consumption. Being low in sodium can result in negative effects such as an electrolyte imbalance. This occurs only under extreme conditions, eg, following an extended period of profuse sweating without fluid replacement (drinking water). Sodium is widely available in food overabundance of sodium causes more health problems. For most people, over consumption triggers thirst, and excess sodium is eliminated though the kidneys.

Nutritionists and doctors recommend limiting sodium intake to no more than 2400mg daily. This is actually fairly difficult because there is so much sodium occurring naturally in foods and a great deal more is added in processing. Salt added to food at the table adds still more (and is discouraged by most health professionals).

Dietary Sources:
Processed meats, Cheese, Margarine and Butter.
RDI: 920-2,300 mg
Toxicity: Includes high blood pressure, premenstrual syndrome and possibly osteoporosis, asthma and urinary stones.

Vanadium
Interest in vanadium as a nutritional substance has been steadily building over the past twenty years. Research indicates that it may have insulin like properties. Vanadium and vanadyl salts stimulate glucose metabolism. Diabetes patients should consult their doctor before taking any vanadium supplement. Vanadium may also have a function role as a building material in bones and teeth.

Dietary Sources:
Whole grain breads and Cereals, Vegetable Oils, Nuts, Root vegetables, Parsley, Fish, Radishes, Dill, Lettuce and Strawberries.
RDI: Recommended Daily Intake has not been set in Australia.
Toxicity: Can easily be toxic if taken in synthetic form. It may cause nerve damage, blood vessel damage, kidney failure, liver damage, stunted growth, loss of appetite and diarrhoea.

Zinc
Zinc is present in all tissues and involved in over 100 enzymatic reactions. It is required for the synthesis of DNA and RNA, protein synthesis, and cell division. It also helps regulate a wide variety of immune system activities. Zinc facilitates wound healing, helps the body use vitamin A, maintains the senses of taste and smell, and helps in the use of insulin. Both zinc deficiency and zinc overload can adversely impact health and cause medical problems. The daily requirement is small (12-15mcg) and can be met from food in most cases. In a small number of people, whose diet includes a large amount of whole grain products and little or no meat, zinc deficiency may become a problem because certain components of whole grains inhibit the absorption of zinc.

Dietary Sources:
Beef (lean), Chicken heart, Egg yolk, Fish, Herring, Lamb, Maple syrup, Milk, Molasses, Oysters, Pork, Sesame seeds, Soybeans, Sunflower seeds, Turkey, Wheat bran, Wheat germ, Whole-grain products, Yeast.
RDI: 12 mg
Toxicity: With the ingestion of 2g or more of zinc, toxicity resulted in gastrointestinal irritation and vomiting in the sulfate form. Excessive consumption of zinc impairs the absorption of copper.

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