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In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight (oxygen, hydrogen, carbon, and nitrogen), are usually not included in lists of major nutrient minerals (nitrogen is considered a "mineral" for plants, as it often is included in fertilizers). These four elements compose about 96% of the weight of the human body, and major minerals (macrominerals) and minor minerals (also called trace elements) compose the remainder.
Nutrient minerals, being elements, cannot be synthesized biochemically by living organisms. Plants get minerals from soil. Most of the minerals in a human diet come from eating plants and animals or from drinking water. As a group, minerals are one of the four groups of essential nutrients, the others of which are vitamins, essential fatty acids, and essential amino acids. The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. All of the remaining elements in a human body are called "trace elements". The trace elements that have a specific biochemical function in the human body are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium.
Most chemical elements that are ingested by organisms are in the form of simple compounds. Plants absorb dissolved elements in soils, which are subsequently ingested by the herbivores and omnivores that eat them, and the elements move up the food chain. Larger organisms may also consume soil (geophagia) or use mineral resources, such as salt licks, to obtain limited minerals unavailable through other dietary sources.
Bacteria and fungi play an essential role in the weathering of primary elements that results in the release of nutrients for their own nutrition and for the nutrition of other species in the ecological food chain. One element, cobalt, is available for use by animals only after having been processed into complex molecules (e.g., vitamin B12) by bacteria. Minerals are used by animals and microorganisms for the process of mineralizing structures, called biomineralization, used to construct bones, seashells, eggshells, exoskeletons and mollusc shells.
Essential chemical elements for humans
Oxygen, hydrogen, carbon and nitrogen are the most abundant elements in the body by weight and make up about 96% of the weight of a human body. Calcium makes up 920 to 1200 grams of adult body weight, with 99% of it contained in bones and teeth. This is about 1.5% of body weight. Phosphorus occurs in amounts of about 2/3 of calcium, and makes up about 1% of a person's body weight. The other major minerals (potassium, sodium, chlorine, sulfur and magnesium) make up only about 0.85% of the weight of the body. Together these eleven chemical elements (H, C, N, O, Ca, P, K, Na, Cl, S, Mg) make up 99.85% of the body. The remaining ~18 ultratrace minerals comprise just 0.15% of the body, or about one hundred grams in total for the average person. Total fractions in this paragraph are amounts based on summing percentages from the article on chemical composition of the human body
Different opinions exist about the essential nature of various ultratrace elements in humans (and other mammals), even based on the same data. For example, there is no scientific consensus on whether chromium is an essential trace element in humans. The United States and Japan designate chromium as an essential nutrient, but the European Food Safety Authority (EFSA), representing the European Union, reviewed the question in 2014 and does not agree.
Most of the known and suggested mineral nutrients are of relatively low atomic weight, and are reasonably common on land, or for sodium and iodine, in the ocean:
|Nutritional elements in the periodic table|
Essential trace elements
Deemed essential trace element by U.S., not by European Union
Suggested function from deprivation effects or active metabolic handling, but no clearly-identified biochemical function in humans
Limited circumstantial evidence for trace benefits or biological action in mammals
No evidence for biological action in mammals, but essential in some lower organisms.
(In the case of lanthanum, the definition of an essential nutrient as being indispensable and irreplaceable is not completely applicable due to the extreme similarity of the lanthanides. The stable early lanthanides up to Sm are known to stimulate the growth of various lanthanide-using organisms.)
Roles in biological processes
|Dietary element||RDA/AI Male/Female (US) [mg]||UL (US and EU) [mg]||Category||High nutrient density
|Terms for deficiency/excess|
|Potassium||4700||NE; NE||A systemic electrolyte and is essential in coregulating ATP with sodium||Sweet potato, tomato, potato, beans, lentils, dairy products, seafood, banana, prune, carrot, orange||hypokalemia / hyperkalemia|
|Chlorine||2300||3600; NE||Needed for production of hydrochloric acid in the stomach and in cellular pump functions||Table salt (sodium chloride) is the main dietary source.||hypochloremia / hyperchloremia|
|Sodium||1500||2300; NE||A systemic electrolyte and is essential in coregulating ATP with potassium||Table salt (sodium chloride, the main source), sea vegetables, milk, and spinach.||hyponatremia / hypernatremia|
|Calcium||1000||2500; 2500||Needed for muscle, heart and digestive system health, builds bone (see hydroxyapatite), supports synthesis and function of blood cells, helps in blood clotting||Dairy products, eggs, canned fish with bones (salmon, sardines), green leafy vegetables, nuts, seeds, tofu, thyme, oregano, dill, cinnamon.||hypocalcaemia / hypercalcaemia|
|Phosphorus||700||4000; 4000||A component of bones (see hydroxyapatite), cells, in energy processing, in DNA and ATP (as phosphate) and many other functions||Red meat, dairy foods, fish, poultry, bread, rice, oats. In biological contexts, usually seen as phosphate||hypophosphatemia / hyperphosphatemia|
|Magnesium||420/320||350; 250||Required for processing ATP and for bones||Spinach, legumes, nuts, seeds, whole grains, peanut butter, avocado||hypomagnesemia (magnesium deficiency) / hypermagnesemia|
|Iron||8/18||45; NE||Required for many proteins and enzymes, notably hemoglobin to prevent anemia||Meat, seafood, nuts, beans, dark chocolate||iron deficiency / iron overload disorder|
|Zinc||11/8||40; 25||Required for several classes of enzymes such as matrix metalloproteinases, liver alcohol dehydrogenase, carbonic anhydrase and zinc finger proteins||Oysters*, red meat, poultry, nuts, whole grains, dairy products||zinc deficiency / zinc toxicity|
|Manganese||2.3/1.8||11; NE||Required co-factor for superoxide dismutase||Grains, legumes, seeds, nuts, leafy vegetables, tea, coffee||manganese deficiency / manganism|
|Copper||0.9||10; 5||Required co-factor for cytochrome c oxidase||Liver, seafood, oysters, nuts, seeds; some: whole grains, legumes||copper deficiency / copper toxicity|
|Iodine||0.150||1.1; 0.6||Required for the synthesis of thyroid hormones||Seaweed (kelp or kombu)*, grains, eggs, iodized salt||iodine deficiency (goiter) / iodism (hyperthyroidism)|
|Chromium||0.035/0.025||NE; NE||Involved in glucose and lipid metabolism, although its mechanisms of action in the body and the amounts needed for optimal health are not well-defined||Broccoli, grape juice (especially red), meat, whole grain products||chromium deficiency / chromium toxicity|
|Molybdenum||0.045||2; 0.6||Required for the functioning of xanthine oxidase, aldehyde oxidase, and sulfite oxidase||Legumes, whole grains, nuts||molybdenum deficiency / molybdenum toxicity|
|Selenium||0.055||0.4; 0.3||Essential to activity of antioxidant enzymes like glutathione peroxidase||Brazil nuts, seafoods, organ meats, meats, grains, dairy products, eggs||selenium deficiency / selenosis|
|Cobalt||none||NE; NE||Required in the synthesis of vitamin B12, but because bacteria are required to synthesize the vitamin, it is usually considered part of vitamin B12 which comes from eating animals and animal-sourced foods (eggs...)||cobalt deficiency / cobalt poisoning|
* One serving of seaweed exceeds the US UL of 1100 μg but not the 3000 μg UL set by Japan.
Blood concentrations of minerals
Minerals are present in a healthy human being's blood at certain mass and molar concentrations. The figure below presents the concentrations of each of the chemical elements discussed in this article, from center-right to the right. Depending on the concentrations, some are in upper part of the picture, while others are in the lower part. The figure includes the relative values of other constituents of blood such as hormones. In the figure, minerals are color highlighted in purple.
Dietitians may recommend that minerals are best supplied by ingesting specific foods rich with the chemical element(s) of interest. The elements may be naturally present in the food (e.g., calcium in dairy milk) or added to the food (e.g., orange juice fortified with calcium; iodized salt fortified with iodine). Dietary supplements can be formulated to contain several different chemical elements (as compounds), a combination of vitamins and/or other chemical compounds, or a single element (as a compound or mixture of compounds), such as calcium (calcium carbonate, calcium citrate) or magnesium (magnesium oxide), or iron (ferrous sulfate, iron bis-glycinate).
The dietary focus on chemical elements derives from an interest in supporting the biochemical reactions of metabolism with the required elemental components. Appropriate intake levels of certain chemical elements have been demonstrated to be required to maintain optimal health. Diet can meet all the body's chemical element requirements, although supplements can be used when some recommendations are not adequately met by the diet. An example would be a diet low in dairy products, and hence not meeting the recommendation for calcium.
The gap between recommended daily intake and what are considered safe upper limits (ULs) can be small. For example, for calcium the U.S. Food and Drug Administration set the recommended intake for adults over 70 years at 1,200 mg/day and the UL at 2,000 mg/day. The European Union also sets recommended amounts and upper limits, which are not always in accord with the U.S. Likewise, Japan, which sets the UL for iodine at 3000 μg versus 1100 for the U.S. and 600 for the EU. In the table above, magnesium appears to be an anomaly as the recommended intake for adult men is 420 mg/day (women 350 mg/day) while the UL is lower than the recommended, at 350 mg. The reason is that the UL is specific to consuming more than 350 mg of magnesium all at once, in the form of a dietary supplement, as this may cause diarrhea. Magnesium-rich foods do not cause this problem.
Elements considered possibly essential for humans but not confirmed
Many ultratrace elements have been suggested as essential, but such claims have usually not been confirmed. Definitive evidence for efficacy comes from the characterization of a biomolecule containing the element with an identifiable and testable function. One problem with identifying efficacy is that some elements are innocuous at low concentrations and are pervasive (examples: silicon and nickel in solid and dust), so proof of efficacy is lacking because deficiencies are difficult to reproduce. Ultratrace elements of some minerals such as silicon and boron are known to have a role but the exact biochemical nature is unknown, and others such as arsenic are suspected to have a role in health, but with weaker evidence.
|Bromine||Possibly important to basement membrane architecture and tissue development, as a needed catalyst to make collagen IV.||bromism|
|Arsenic||Essential in rat, hamster, goat and chicken models, but no research has been done in humans.||arsenic poisoning|
|Nickel||Nickel is an essential component of several enzymes, including urease and hydrogenase. Although not required by humans, some are thought to be required by gut bacteria, such as urease required by some varieties of Bifidobacterium. In humans, nickel may be a cofactor or structural component of certain metalloenzymes involved in hydrolysis, redox reactions and gene expression. Nickel deficiency depressed growth in goats, pigs, and sheep, and diminished circulating thyroid hormone concentration in rats.||Nickel toxicity|
|Fluorine||Fluorine (as fluoride) is not considered an essential element because humans do not require it for growth or to sustain life. Research indicates that the primary dental benefit from fluoride occurs at the surface from topical exposure. Of the minerals in this table, fluoride is the only one for which the U.S. Institute of Medicine has established an Adequate Intake.||Fluoride poisoning|
|Boron||Boron is an essential plant nutrient, required primarily for maintaining the integrity of cell walls. Boron has been shown to be essential to complete the life cycle in representatives of all kingdoms of life. In animals, supplemental boron has been shown to reduce calcium excretion and activate vitamin D.||No acute effects (LD50 of boric acid is 2.5 grams per kilogram body weight)
Chronic effects of long term high dose boron exposure are not fully elucidated
|Lithium||Based on plasma lithium concentrations, biological activity and epidemiological observations, there is evidence, not conclusive, that lithium is an essential nutrient.||Lithium toxicity|
|Strontium||Strontium has been found to be involved in the utilization of calcium in the body. It has promoting action on calcium uptake into bone at moderate dietary strontium levels, but a rachitogenic (rickets-producing) action at higher dietary levels.||Certain forms of Rickets|
|Other||Silicon and vanadium have established, albeit specialized, biochemical roles as structural or functional cofactors in other organisms, and are possibly, even probably, used by mammals (including humans). By contrast, tungsten, the early lanthanides, and cadmium have specialized biochemical uses in certain lower organisms, but these elements appear not to be utilized by mammals. Other elements considered to be possibly essential include aluminium, germanium, lead, rubidium, and tin.||Multiple|
Minerals can be bioengineered by bacteria which act on metals to catalyze mineral dissolution and precipitation. Mineral nutrients are recycled by bacteria distributed throughout soils, oceans, freshwater, groundwater, and glacier meltwater systems worldwide. Bacteria absorb dissolved organic matter containing minerals as they scavenge phytoplankton blooms. Mineral nutrients cycle through this marine food chain, from bacteria and phytoplankton to flagellates and zooplankton, which are then eaten by other marine life. In terrestrial ecosystems, fungi have similar roles as bacteria, mobilizing minerals from matter inaccessible by other organisms, then transporting the acquired nutrients to local ecosystems.
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