In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, most are not.^[1][2][3] Minerals are one of the four groups of essential nutrients, the others of which are vitamins, essential fatty acids, and essential amino acids.^[4] The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium.^[2] The remaining elements are called "trace elements". The generally accepted trace elements are iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, and selenium;^[5] there is some evidence that there may be more.

Four elements comprise 96% of the human body by weight: carbon, hydrogen, oxygen, and nitrogen) (CHON). These elements are usually not included in lists of nutrient minerals. They are sometimes referred to as macrominerals. The minor minerals (also called trace elements) compose the remainder and are usually the focus of discussions of minerals in the diet.

Plants obtain minerals from soil.^[6] Plants are ingested by animals, thus moving minerals up the food chain. Larger organisms may also consume soil (geophagia) or use mineral resources, such as salt licks, to obtain minerals.

Finally, although mineral and elements are in many ways synonymous, minerals are only bioavailable to the extent that they can be absorbed. To be absorbed, minerals either must be soluble or readily extractable by the consuming organism. For example, molybdenum is an essential mineral, but metallic molybdenum has no nutritional benefit. Many molybdates are sources of molybdenum.

Nineteen chemical elements are known to be required to support human biochemical processes by serving structural and functional roles, and there is evidence for around ten more.^[1][7]

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.^[2] Phosphorus occurs in amounts of about 2/3 of calcium, and makes up about 1% of a person's body weight.^[8] 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.

Some diversity of opinion exist about the essential nature of various ultratrace elements in humans (and other mammals), even based on the same data. For example, whether chromium is essential in humans is debated. No Cr-containing biochemical has been purified. The United States and Japan designate chromium as an essential nutrient,^[9][10] but the European Food Safety Authority (EFSA), representing the European Union, reviewed the question in 2014 and does not agree.^[11]

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. They also tend to have soluble compounds at physiological pH ranges: elements without such soluble compounds tend to be either non-essential (Al) or, at best, may only be needed in traces (Si).^[1]

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).^{[citation needed]}

The dietary focus on chemical elements derives from an interest in supporting the biochemical reactions of metabolism with the required elemental components.^[34] 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 list of minerals required for plants is similar to that for animals. Both use very similar enzymes, although differences exist. For example, legumes host molybdenum-containing nitrogenase, but animals do not. Many animals rely on hemoglobin (Fe) for oxygen transport, but plants do not. Fertilizers are often tailored to address mineral deficiencies in particular soils. Examples include molybdenum deficiency, manganese deficiency, zinc deficiency, and so on.

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.^[5] 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.^[34] 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.^[5] In particular, trace arsenic seems to have a positive effect on some organisms, but so does lead, showcasing the uncertainty behind whether some trace elements are truly essential.^[1] Strontium is tolerated and is a component of some drugs,^[37] but it is not essential, only beneficial.^[1] Non-essential elements can sometimes appear in the body when they are chemically similar to essential elements (e.g. Rb⁺ and Cs⁺ replacing Na⁺), so that essentiality is not the same thing as uptake by a biological system.^[1]

Diverse ions are used by animals and microorganisms for the process of mineralizing structures, called biomineralization, used to construct bones, seashells, eggshells,^[53] exoskeletons and mollusc shells.^{[54][citation needed]}

Minerals can be bioengineered by bacteria which act on metals to catalyze mineral dissolution and precipitation.^[55] Mineral nutrients are recycled by bacteria distributed throughout soils, oceans, freshwater, groundwater, and glacier meltwater systems worldwide.^[55][56] Bacteria absorb dissolved organic matter containing minerals as they scavenge phytoplankton blooms.^[56] Mineral nutrients cycle through this marine food chain, from bacteria and phytoplankton to flagellates and zooplankton, which are then eaten by other marine life.^[55][56] 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.^[57][58]

• Food composition
• Human nutrition
• Micronutrient
• Mineral deficiency