Dietary minerals (also known as mineral nutrients) are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen present in common organic molecules. Examples of mineral elements include calcium, magnesium, potassium, sodium, zinc, and iodine. Most minerals that enter into the dietary physiology of organisms consist of simple chemical elements. Larger aggregates of minerals need to be broken down for absorption. Bacteria play an essential role in the weathering of primary minerals that results in the release of nutrients for their own nutrition and for the nutrition of others in the ecological food chain. Scientists are only recently starting to appreciate the magnitude and role that microorganisms have in the global cycling and formation of biological minerals. Plants absorb dissolved minerals in soils, which are subsequently picked up by the herbivores that eat them and so on, the minerals move up the food chain. Larger organisms may also consume soil (geophagia) and visit mineral licks to obtain limiting mineral nutrients they are unable to acquire through other components of their diet.
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Some sources state that sixteen chemical elements are required to support human biochemical processes by serving structural and functional roles as well as electrolytes:[1] As many as 26 elements are suggested to be used by mammals, as a result of studies of biochemical, special uptake, and metabolic handling studies.[2] However, many of these additional elements have no well-defined biochemical function known at present. Most of the known and suggested dietary elements are of relatively low atomic weight, and are reasonably common on land, or at least, common in the ocean (iodine, sodium):
Periodic table highlighting dietary elements
| H | He | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Li | Be | B | C | N | O | F | Ne | |||||||||||
| Na | Mg | Al | Si | P | S | Cl | Ar | |||||||||||
| K | Ca | Sc | Ti | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Ga | Ge | As | Se | Br | Kr | |
| Rb | Sr | Y | Zr | Nb | Mo | Tc | Ru | Rh | Pd | Ag | Cd | In | Sn | Sb | Te | I | Xe | |
| Cs | Ba | La | * | Hf | Ta | W | Re | Os | Ir | Pt | Au | Hg | Tl | Pb | Bi | Po | At | Rn |
| Fr | Ra | Ac | ** | Rf | Db | Sg | Bh | Hs | Mt | Ds | Rg | |||||||
| * | Ce | Pr | Nd | Pm | Sm | Eu | Gd | Tb | Dy | Ho | Er | Tm | Yb | Lu | ||||
| ** | Th | Pa | U | Np | Pu | Am | Cm | Bk | Cf | Es | Fm | Md | No | Lr | ||||
| The four organic basic elements | Quantity elements | Essential trace elements | Suggested function from biochemistry and handling but no identified biological function in humans |
The following play important roles in biological processes:
| Dietary element | RDA/AI | Description | Category | Insufficiency | Excess |
|---|---|---|---|---|---|
| Potassium | 4700 mg | Quantity | is a systemic electrolyte and is essential in coregulating ATP with sodium. Dietary sources include legumes, potato skin, tomatoes, and bananas. | hypokalemia | hyperkalemia |
| Chlorine | 2300 mg | Quantity | is 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 mg | Quantity | is a systemic electrolyte and is essential in coregulating ATP with potassium. Dietary sources include table salt (sodium chloride, the main source), sea vegetables, milk, and spinach. | hyponatremia | hypernatremia |
| Calcium | 1300 mg | Quantity | is needed for muscle, heart and digestive system health, builds bone, supports synthesis and function of blood cells. Dietary sources of calcium include dairy products, canned fish with bones (salmon, sardines), green leafy vegetables, nuts and seeds. | hypocalcaemia | hypercalcaemia |
| Phosphorus | 700 mg | Quantity | is a component of bones (see apatite), cells, in energy processing and many other functions.", is found in red meat, dairy foods, fish, poultry, bread, rice, oats. [3] [4] In biological contexts, usually seen as phosphate.[5] | hypophosphatemia | hyperphosphatemia |
| Magnesium | 420 mg | Quantity | is required for processing ATP and for bones. Dietary sources include nuts, soy beans, and cocoa mass. | hypomagnesemia, magnesium deficiency |
hypermagnesemia |
| Zinc | 11 mg | Trace | is pervasive and required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, and carbonic anhydrase. | zinc deficiency | zinc toxicity |
| Iron | 18 mg | Trace | is required for many proteins and enzymes, notably hemoglobin to prevent anemia. Dietary sources include red meat, leafy green vegetables, fish (tuna, salmon), eggs, dried fruits, beans, whole grains, and enriched grains. | anaemia | iron overload disorder |
| Manganese | 2.3 mg | Trace | is a cofactor in enzyme functions. | manganese deficiency | manganism |
| Copper
Main article: Copper in health
|
900 µg | Trace | is required component of many redox enzymes, including cytochrome c oxidase. | copper deficiency | copper toxicity |
| Iodine | 150 µg | Trace | is required not only for the synthesis of thyroid hormones, thyroxine and triiodothyronine and to prevent goiter, but also, probably as an antioxidant, for extrathyroidal organs as mammary and salivary glands and for gastric mucosa and immune system (thymus): | iodine deficiency | iodism |
| Selenium | 55 µg | Trace | a cofactor essential to activity of antioxidant enzymes like glutathione peroxidase. | selenium deficiency | selenosis |
| Molybdenum | 45 µg | Trace | the oxidases xanthine oxidase, aldehyde oxidase, and sulfite oxidase[6] | molybdenum deficiency |
Dietitians may recommend that dietary elements 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, 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 (as carbonate, citrate, etc.) or magnesium (as oxide, etc.), chromium (usually as picolinate) or iron (as bis-glycinate). [7]
The dietary focus on chemical elements derives from an interest in supporting the biochemical reactions of metabolism with the required elemental components.[8] 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 requirements (e.g., calcium, which is found mainly in dairy products) are not adequately met by the diet, or when chronic or acute deficiencies arise from pathology, injury, etc. Research has supported that altering inorganic mineral compounds (carbonates, oxides, etc.) by reacting them with organic ligands (amino acids, organic acids, etc.) improves the bioavailability of the supplemented mineral.[9]
Many 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.[8]
| Element | Description | Excess |
|---|---|---|
| Sulfur | Relatively large quantities of sulfur are required, but there is no RDA,[10] as the sulfur is obtained from and used for amino acids, and therefore should be adequate in any diet containing enough protein. | (primarily associated with compounds) |
| Cobalt | Cobalt is required in the synthesis of vitamin B12, but because bacteria are required to synthesize the vitamin, it is usually considered part of vitamin B12 deficiency rather than its own dietary element deficiency. | Cobalt poisoning |
| Nickel | There have been occasional studies asserting the essentiality of nickel,[11] but it currently has no RDA. | Nickel toxicity |
| Chromium | Chromium has been described as nonessential to mammals,[12][13] with some role in sugar metabolism in humans. Despite a market for the supplement chromium picolinate, definitive biochemical evidence for a physiological function is lacking.[14] | Chromium toxicity |
| Fluorine | Fluorine (as Fluoride) is not generally considered an essential mineral element because humans do not require it for growth or to sustain life. However, if one considers the prevention of dental caries an important criterion in determining essentiality, then fluoride might well be considered an essential trace element. However, recent research indicates that the primary action of fluoride occurs topically (at the surface).[15][16] | Fluoride poisoning |
| Boron | Boron has been found to be essential for the utilization of vitamin D and calcium in the body.[17] | |
| 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.[18] | Rachitogenic |
| Other | Arsenic, 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, bromine, and cadmium have specialized biochemical uses in certain lower organisms, but these elements appear not to be utilized by humans.[19] | Multiple |
Recent studies have shown a tight linkage between living organisms and minerals on this planet. This has let to the redefinition of minerals as "an element or compound, amorphous or crystalline, formed through 'biogeochemical' processes. The addition of `bio' reflects a greater appreciation, although an incomplete understanding, of the processes of mineral formation by living forms."[20]:621 Biologists and geologists have only recently started to appreciate the magnitude of mineral biogeoengineering. Bacteria have contributed to the formation of minerals for billions of years and critically define the biogeochemical mineral cycles on this planet. Microorganisms can precipitate metals from solution contributing to the formation of ore deposits in addition to their ability to catalyze mineral dissolution, to respire, precipitate, and form minerals.[21][22][23]
Most minerals are inorganic in nature. Mineral nutrients refers to the smaller class of minerals that are metabolized for growth, development, and vitality of living organisms.[24][25][20] Mineral nutrients are recycled by bacteria that are freely suspended in the vast water columns of the worlds oceans. They absorb dissolved organic matter containing mineral nutrients as they scavenge through the dying individuals that fall out of large phytoplankton blooms. Flagellates are effective bacteriovores and are also commonly found in the marine water column. The flagellates are preyed upon by zooplankton while the phytoplankton concentrates on the larger particulate matter that is suspended in the water column as they are consumed by larger zooplankton, with fish as the top predator. Mineral nutrients cycle through this marine food chain, from bacteria and phytoplankton to flagellates and zooplankton who are then eaten by fish. The bacteria are important in this chain because only they have the physiological ability to absorb the dissolved mineral nutrients from the sea. These recycling principals from marine environments apply to many soil and freshwater ecosystems as well.[26][27]
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