Health Care

The Low Down on Minerals

Minerals play a vital role in maintaining good health and fitness. As with vitamins, the minerals we need on a daily basis can all be obtained from a well balanced diet, without the need for supplements. Recommended daily amounts (RDA) are based on the needs of an average adult. Athletes and strength trainers will have a higher requirement, but a well balanced, higher caloric intake should compensate for this.

There is usually no need for supplementation, but a general multi-mineral tablet or capsule can be taken to without ill-effect. The list of minerals can be broken down into two main categories based on the amount required: macro and micro (trace).

The following tables outline the functions of each essential mineral and summarize some of the main food sources. The table also provides information on the recommended daily allowance (RDA) or the guidelines for adequate intake (AI) for an average adult (AI values are marked with *).

The Macro Minerals

Mineral Adult RDA / AI* Food Sources Functions
Calcium 1,000* mg/d (ages 19 – 50), 1,200* mg/d (ages 51+) Milk, cheese, yogurt, corn tortillas, calcium-set tofu, Chinese cabbage, kale, broccoli. Essential role in blood clotting, Also important for muscle growth and contraction, nerve transmission and bone and tooth formation.
Chloride 500* mg/d Table salt (sodium chloride), kelp, rye flour. Helps to regulate the pressure that causes fluids to pass in and out of cell membranes.
Magnesium 400 mg/d (males aged 19 – 30), 420 mg/d (males aged 31 – 70), 310 mg/d (females aged 19 – 30), 320 mg/d (females aged 31 – 70) Green leafy vegetables, unpolished grains, nuts, meat, starches, milk. Cofactor for enzyme systems. Helps to metabolize carbohydrate and protein, assists with neuromuscular contractions and the regulation of body temperature.
Phosphorus 700 mg/d Milk, yogurt, ice cream, cheese, peas, meat, eggs, some cereals and breads. Important for maintenance of pH, storage and transfer of energy and nucleotide synthesis. Helps build strong bones and teeth. Assists in all phases of calcium metabolism. Also helps metabolism of carbohydrate, protein and fat; growth, repair and maintenance of cells, stimulation of muscle contraction and energy production.
Potassium 1,600* to 3,500* mg/d Bananas, potatoes, fruit, vegetables. Helps maintain fluid balance on each side of cell membrane; promotes growth, stimulates nerve impulses for muscular contractions; helps convert glucose to glycogen and synthesis of muscle protein from amino acids.
Sodium 2.4* mg/d Found in almost all foods. Helps maintain fluid balance on each side of cell membrane; keeps other blood minerals soluble and assists with muscular contractions and nerve transmission.

Sources: National Academy of Sciences. Institute of Medicine. Food and Nutrition Board / USDA

The Micro (Trace) Minerals

Mineral Adult RDA / AI* Food Sources Functions
Chromium 35* μg/d (males aged 19 – 50), 30* μg/d (males aged 51+), 25* μg/d (females aged 19 – 50), 20* μg/d (females aged 51+) Some cereals, meats, poultry, fish, brewer’s yeast, beer, vegetable oils. Helps to maintain normal blood glucose levels and metabolize fat. Helps insulin bind to cells.
Copper 900* μg/d Organ meats, seafood, nuts, seeds, wheat bran cereals, whole grain products, cocoa products, potatoes, tomato juice. Component of enzymes in iron metabolism, necessary for the formation of hemoglobin.
Fluoride 4* mg/d (males), 3* mg/d (females) Fluoridated water, tea, seafood, fluoridated dental products. Inhibits the initiation and progression of dental caries and stimulates new bone formation.
Iodine 150 μg/d Seafood, seaweed, iodized salt, processed foods, milk, mushrooms. Component of the thyroid hormones; and prevents goiter and cretinism. Essential for the oxidation rates of cells, energy production, growth and development and metabolism.
Iron 8 mg/d (males), 18 mg/d (females aged 19 – 50), 8 mg/d (females aged 51+) Fruits, leafy green vegetables, fortified bread and grain products such as cereal (nonheme iron sources), meat, liver, oysters and poultry (heme iron sources) Component of hemoglobin and numerous enzymes; prevents microcytic hypochromic anemia. Transports oxygen to cells for energy.
Manganese 2.3* mg/d (males), 1.8* mg/d (females) Nuts, legumes, tea, whole grains, leafy green vegetables. Involved in the formation of bone, as well as in enzymes involved in amino acid, cholesterol, and carbohydrate metabolism. Necessary for normal development of bones and connective tissues.
Molybdenum 45 μg/d Legumes, grain products, nuts, milk. Cofactor for enzymes involved in catabolism of sulfur amino acids, purines and pyridines. Assists with metabolism of fats.
Selenium 55 μg/d Organ meats, seafood, eggs, vegetables and fruit (depending on soil selenium content). Defense against oxidative stress and regulation of thyroid hormone action, and the reduction and oxidation status of vitamin C and other molecules. Works in conjunction with vitamin E to protect cells from destruction.
Zinc 11 mg/d (males), 8 mg/d (females) Fortified cereals, red meats, oysters and other seafood. Component of multiple enzymes and proteins; involved in the regulation of gene expression. Plays an important role in formation of protein in the body and assists in wound healing, blood formation, as well as general growth and maintenance of the tissues.

Sources: National Academy of Sciences. Institute of Medicine. Food and Nutrition Board / USDA