Nutrition

Micronutrients are subdivided according to the quantities needed in the human diet. If more than 100 milligrams (mg) per day of an element is needed, it is classed as a mineral. The seven essential minerals are calcium, magnesium, phosphorus, sodium, potassium, sulfur, and chlorine. Substances that are essential but needed in amounts of less than 100 mg per day are called trace elements. These are iron, copper, iodine, manganese, zinc, molybdenum, selenium, and chromium. There are likely others (such as boron) that are yet to be identified.

Calcium and phosphorus are both used structurally to form bones and teeth. Lesser known but vital functions of calcium include its uses as an enzyme activator and as a regulator of nerve and muscle activity. Phosphorous is also a component of nucleotide molecules that are structural components of the nucleic acids, DNA and RNA, and of the energy transfer molecules such as ATP, NAD, and FAD.

Magnesium is found in bones too, but, more importantly, it is needed in adequate amounts to work with calcium in regulating nerve and muscle activity. In fact, an early symptom of magnesium shortage can be irregular heart action. Sodium is necessary for the proper functioning of the nerves and muscles. Sodium is more concentrated in the fluids outside of the cells than the intraocular fluids. Sodium is more often consumed in excess because it is easy to enhance the flavors of foods by adding table salt (sodium chloride). Potassium ions are most concentrated in the fluid inside cells. There is evidence that high blood pressure can be prevented or controlled by increasing one's intake of potassium. Chloride functions as an electrolyte balance for the sodium and other positive ions in cell and tissue fluids and is necessary for the salivary enzyme ptyalin to help digest starch. Sulfur is a component of three amino acids and is part of the enzyme molecules active in the oxidation of fatty acids.

These minerals must be in their ionic form so as to be soluble and absorbable. Many minerals are often chelated, that is, attached to a larger organic particle such as an amino acid, or anions such as gluconate, lactate, or citrate to be properly observed. Some trace elements function in cooperation with an enzyme or a vitamin molecule to bring about physiological responses.

More and more, people are choosing foods for their vitamin or mineral content, because the foods provide specific nutrients that may otherwise be missing. Adding daily supplements of vitamins C, E, and A (or its precursor beta carotene) to diets may promote good health and fight disease.