A mineral is an inorganic element necessary for the body to build tissues, regulate body fluids, or assist in various body functions. Minerals are found in all body tissues. Any abnormal concentration of minerals in the blood can help diagnose different disorders. Minerals cannot provide energy by themselves, but in their role as body regulators, they contribute to the production of energy within the body.
Minerals are found in water and in natural (unprocessed) foods, together with proteins, carbohydrates, fats, and vitamins. Minerals in the soil are absorbed by growing plants. Humans obtain minerals by eating plants grown in mineral-rich soil or by eating animals that have eaten such plants. The specific mineral content of food is determined by burning the food and then chemically analyzing the remaining ash.
Highly processed or refined foods such as sugar and white flour contain almost no minerals. Iron, together with the vitamins thiamine, riboflavin, niacin, and folate, are commonly added to white flour and cereals, which are then labeled enriched foods.
Most minerals in food occur as salts, which are soluble in water. Therefore, the minerals leave the food and remain in the cooking water. Foods should be cooked in as little water as possible or, preferably, steamed, and any cooking liquid should be saved to be used in soups, gravies, and white sauces. Using this liquid improves the flavor as well as the nutrient content of foods to which it is added.
CLASSIFICATION
Minerals are divided into two groups. They are the major minerals, so named because each is required in amounts greater than 100 mg a day, and the trace minerals, which are needed in amounts smaller than 100 mg a day.
Electrolytes are essential in maintaining the body’s fluid balance, and they contribute to its electrical balance, assist in its transmission of nerve impulses and contraction of muscles, and help regulate its acid-base balance.
Normally, a balanced diet will maintain electrolyte balance. However, in cases of severe diarrhea, vomiting, high fever, or burns, electrolytes are lost, and the electrolyte balance can be upset. Medical intervention will be necessary to replace the lost electrolytes.
Scientists lack exact information on some of the trace elements, although they do know that trace elements are essential to good health. The study of these elements continues to reveal their specific relationships to human nutrition. A balanced diet is the only safe way of including minerals in the amounts necessary to maintain health.
| Category | Age | Copper (µg) | Manganese (mg) | Chromium (µg) | Molybdenum (µg) |
| Infants | 0–0.6 months | 200 | 0.003 | 0.2 | 2 |
| 7–12 months | 220 | 0.6 | 5.5 | 3 | |
| Children and adolescents | 1–3 years | 340 | 1.2 | 11 | 17 |
| 4–8 years | 440 | 1.5 | 15 | 22 | |
| 9–13 years | 700 | 1.9 | 21–25 | 34 | |
| Adults | 14–18 years | 890 | 2.2 | 24–35 | 43 |
| 19–70 years | 900 | 1.8–2.3 | 25–36 | 45 |
The Food and Nutrition Board of the National Academy of Sciences–National Research Council (hereafter NRC) has recommended dietary allowances for minerals where research indicates knowledge is adequate to do so.
For those minerals where there remains some uncertainty as to amounts of specific human requirements, the NRC has provided a table of Adequate Intakes of selected minerals. The NRC recommends that the upper levels of listed amounts not be habitually exceeded. In addition, the Institute of Medicine has developed Daily Reference Intakes (DRIs) for calcium, fluoride, phosphorus, and magnesium. The DRI incorporates Estimated Average Requirements (EAR), the RDA, and Tolerable Upper Intake Levels.
TOXICITY
Because it is known that minerals are essential to good health, some would-be nutritionists will make claims that “more is better.” Ironically, more can be hazardous to one’s health when it comes to minerals. In a healthy individual eating a balanced diet, there will be some normal mineral loss through perspiration and saliva, and amounts in excess of body needs will be excreted in urine and feces. However, when concentrated forms of minerals are taken on a regular basis, over a period of time, they become more than the body can handle, and toxicity develops. An excessive amount of one mineral can sometimes cause a deficiency of another mineral. In addition, excessive amounts of minerals can cause hair loss and changes in the blood, hormones, bones, muscles, blood vessels, and nearly all tissues. Concentrated forms of minerals should be used only on the advice of a physician.
Major Minerals
| Name | Food sources | Functions | Deficiency/toxicity |
| Calcium (Ca++) | Milk, cheese Some dark green, leafy vegetables |
Development of bones and teeth
Transmission of nerve impulses Blood clotting Normal heart action Normal muscle activity |
Deficiency
Osteoporosis Osteomalacia Rickets Tetany Retarded growth Poor tooth and bone formation |
| Phosphorus (P) | Milk, cheese
Lean meat Poultry Fish Whole-grain cereals Legumes Nuts |
Development of bones and teeth
Maintenance of normal acid-base balance of the blood Constituent of all body cells Necessary for effectiveness of some vitamins Metabolism of carbohydrates, fats, and proteins |
Deficiency
Poor tooth and bone formation Weakness Anorexia General malaise |
| Potassium (K+) | Oranges
Dried fruits Vegetables Legumes Milk Cereals Meat |
Contraction of muscles
Maintenance of fluid balance Transmission of nerve impulses Osmosis Regular heart rhythm Cell metabolism |
Deficiency
Hypokalemia Muscle weakness Confusion Abnormal heartbeat Toxicity Hyperkalemia Potentially life threatening irregular heartbeats
|
| Sodium (Na+) | Table salt,
Poultry Milk, cheese |
Maintenance of fluid balance
Transmission of nerve impulses Osmosis Acid-base balance Regulation of muscle and nerve irritability
|
Deficiency
Nausea Exhaustion Muscle cramps Toxicity Increase in blood pressure Edema |
| Chloride (Cl-) | Table salt
Eggs Seafood Milk |
Gastric acidity
Regulation of osmotic pressure Osmosis Fluid balance Acid-base balance Formation of hydrochloric acid |
Deficiency
Imbalance in gastric acidity Nausea Exhaustion |
| Magnesium (Mg++) | Green, leafy vegetables
Whole grains Nuts Milk Legumes Bananas |
Synthesis of ATP
Transmission of nerve impulses Activation of metabolic enzymes Constituent of bones, muscles, and red blood cells Necessary for healthy muscles and nerves |
Deficiency
Normally unknown Mental, emotional, and muscle disorders |
| Sulfur (S) | Eggs
Poultry Fish |
Maintenance of protein structure
For building hair, nails, and all body tissues Constituent of all body cells |
Unknown |
| Iron (Fe+) | Muscle meats
Poultry Shellfish Liver Legumes Dried fruits Whole-grain or enriched breads and cereals Dark green and leafy vegetables |
Transports oxygen and carbon dioxide
Component of hemoglobin and myoglobin Component of cellular enzymes essential for energy production
|
Deficiency
Iron deficiency anemia characterized by weakness, dizziness, loss of weight, and pallor Toxicity Hemochromatosis (genetic) Can be fatal to children May contribute to heart disease Injure liver |
| Iodine (I-) | Iodized salt
Seafood |
Regulation of basal metabolic rate
|
Deficiency
Goiter Cretinism Myxedema |
| Zinc (Zn+) | Seafood, especially oysters
Eggs Milk Legumes |
Formation of collagen
Component of insulin Component of many vital enzymes Wound healing Taste acuity Essential for growth Immune reactions |
Deficiency
Dwarfism, hypogonadism, anemia Loss of appetite Skin changes Impaired wound healing Decreased taste acuity |
| Selenium (Se-) | Seafood
Kidney Liver Muscle meats Grains |
Constituent of most body tissue
Needed for fat metabolism Antioxidant functions |
Deficiency
Unclear, but related to Keshan disease Muscle weakness Toxicity Vomiting Loss of hair and nails Skin lesions |
| Copper (Cu+) | Liver
Shellfish, oysters Legumes Nuts Whole grains |
Essential for formation of hemoglobin and red blood cells
Component of enzymes Wound healing Needed metabolically for the release of energy |
Deficiency
Anemia Bone disease Disturbed growth and metabolism Toxicity Vomiting; diarrhea Wilson’s disease (genetic)
|
| Manganese (Mn+) | Whole grains
Nuts Fruits Tea |
Component of enzymes
Bone formation Metabolic processes |
Deficiency
Unknown Toxicity Possible brain disease |
| Fluoride (F-) | Fluoridated water
Seafood |
Increases resistance to tooth decay
Component of bones and teeth |
Deficiency
Tooth decay Possibly osteoporosis Toxicity Discoloration of teeth (mottling) |
| Chromium (Cr) | Meat
Vegetable oil Whole-grain cereal and nuts Yeast |
Associated with glucose and lipid metabolism | Deficiency
Possibly disturbances of glucose metabolism |
| Molybdenum (Mo) | Dark green, leafy vegetables
Liver Cereal Legumes |
Enzyme functioning
Metabolism |
Deficiency
Unknown Toxicity Inhibition of copper absorption |
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