These minerals and other substances are used in medicine, historically or now, and play an important role in human and animal biology. For plant minerals, see agricultural minerals.
The human body needs several elements to survive. Four elements (carbon, hydrogen, nitrogen, and oxygen) are needed in large quantities but easily available in food and water. Seven elements are required in significant quantities (listed in order of importance):
Calcium builds bone and is incorporated into other tissues.
Phosphorus is necessary for bones and for the energy molecule ATP.
Potassium along with sodium regulates conductivity, particularly at the nerve endings. Both also regulate the energy molecule ATP.
Sulfur is incorporated into critical amino acids and therefore proteins.
Sodium and chlorine from salt are the electrolyte in blood.
Magnesium is found in bones.
The human body also needs certain elements in lesser quantities. These are the commonly-agreed-on minor nutrients:
Iron is the critical element in hemoglobin.
Cobalt is the key atom in vitamin B12. That vitamin is the only source of cobalt that the human body can absorb, obtained from eating animal products.
Copper is incorporated into several enzymes.
Zinc is required for several enzymes and is used in body chemistry generally.
Molybdenum is needed for trace reactions.
Iodine is taken up by the thyroid.
Bromine is needed for tissue development.
Selenium is used by antioxidant enzymes.
Finally, some elements are needed in such tiny amounts that deficiency diseases are never observed. The trace elements are not entirely agreed-upon, but they include the following two and possibly others:
The idea that a variety of foods is needed for good health is one that predates civilization. For example, salt (for sodium and chlorine) is required in substantial enough quantities that it is a primary taste sensation. A deficiency of any of these elements will trigger disease symptoms. The link between the disease and its treatment (more of a specific food) is not generally one that was known before modern medical studies.
Water occupies a unique position among substances necessary to life.
Elements are not the only nutrients that the human body needs. A vitamin is an organic molecule that is necessary in minor amounts, one that generally cannot be manufactured in the body. Plants and other animals must provide it.
As with dietary elements, lack of a vitamin will cause a disease, one that is generally more specific and obvious than those linked to element deficiencies. The most famous of these diseases and treatments is probably scurvy, which is caused by lack of Vitamin C (ascorbic acid). During the Age of Discovery (which started in the 15th century), sailors on long sea voyages became ill with scurvy, a disease that causes bleeding at the gums, lethargy, and more serious symptoms leading ultimately to death. Scottish doctor James Lind in 1747 discovered that citrus fruits are a prevention. He suggested that British ships carry limes and lemons, a policy that the Royal Navy adopted. Hency, British sailors became known as "limies".
Vitamins have been given letter designations in addition to their chemical names. The various "B" vitamins also have number subscripts. These are actually different chemicals and are referred to collectively as the "vitamin B complex". B vitamins occur together in unprocessed foods, such as whole grains. The known vitamins are as follows:
Vitamin A (retinol), found in liver and eggs; a deficiency causes night blindness.
Vitamin B1 (thiamine); a deficiency causes beriberi.
Vitamin B2 (riboflavin); the deficiency is called ariboflavinosis.
Vitamin B3 (niacin); a deficiency causes pellagra.
Vitamin B5 (pantothenic acid). A deficiency is uncommon.
Vitamin B6 (pyridoxine); a deficiency may cause anemia, hypertension, and other symptoms.
Vitamin B7 (biotin); a deficiency in infants can impair development.
Vitamin B9 (folic acid); a deficiency can cause anemia and birth defects.
Vitamin B12 (cobalamins), not found in plants; a deficiency can cause anemia, neuropathy, and other symptoms. This is the only source of cobalt for humans.
Vitamin C (ascorbic acid), found in citrus fruits; a deficiency causes scurvy.
Vitamin D (calciferol), manufactured in the skin by sunlight, and only available in dietary supplements; a deficiency causes rickets.
Vitamin E (tocopherol), found in plant oils; a deficiency causes neurological disorders.
Vitamin K (phylloquinone), found in green leaves, required for bone protein formation.
The missing B subscripts designate compounds once thought to be vitamins but now known not to be.
Vitamins are in some cases added to ("fortified") foods; for example, niacin may be added back to white rice, and vitamin D is often added to milk. Vitamins are also available in pill form.
Elements and simple substances used in medicine fall into a few categories.
Disinfectants are applied in and around wounds to kill bacteria and prevent infection. These are generally substances that are minorly toxic. Tincture of iodine is used this way. Alcohols are popular and cheap disinfectants, especially isopropyl alcohol (C3H7OH). In fact, although hand disinfecting stations have sprung up in public places around the developed world, only those that use alcohol have been shown to be effective.
Sedatives and anesthetics numb pain, induce sleep, or make a patient unconscious. Bromine was historically a sedative, but has fallen out of favor because of toxicity concerns. Ether gas (diethyl ether) was probably the first general anesthetic, but is now completely abandoned in favor of sophisticated chemical mixtures. Nitrous oxide (N2O, "laughing gas") has been used as a painkiller and weak anesthetic for over 150 years.
Oxygen is used in medicine. Obviously required for respiration, it is delivered in pure or nearly pure form to patients with breathing problems.
Activated charcoal is a very porous form of coal that is ingested as a treatment for poisoning. It has strong adsorption properties, but is not to be used on substances that react chemically with carbon.
Surgical instruments, implants, and dental fillings are made from inert metals such as tantalum and platinum.