Dietary minerals are chemical elements required by living organisms. They can be either bulk minerals (required in relatively large amounts) or trace minerals (required only in very small amounts).
These can be naturally occurring in food or added in elemental or mineral form, such as calcium carbonate or sodium chloride. Some of these additives come from natural sources such as ground oyster shells. Sometimes minerals are added to the diet separately from food, as vitamin and mineral supplements and in dirt eating, called pica or geophagy.
Appropriate intake levels of each dietary mineral must be sustained to maintain physical health. Excessive intake of a dietary mineral may either lead to illness directly or indirectly because of the competitive nature between mineral levels in the body. For example, large doses of zinc are not really harmful unto themselves, but will lead to a harmful copper deficiency (unless compensated for, as in the Age-Related Eye Disease Study).
Soils in different geographic areas contain varying quantities of minerals.
In human nutrition, the most important dietary minerals include (in alphabetical order):
Secondary dietary minerals. Standards of evidence vary for different elements, and not all have been definitively established as essential to human nutrition. Elements for which convincing scientific evidence is lacking are marked as suspect. This category includes:
Other elements essential to life include calcium, carbon, hydrogen, nitrogen, oxygen, phosphorus, sodium and sulfur. These are not generally considered trace elements, as they are needed in larger quantities. Iron and potassium are needed in larger quantities than the other listed minerals and are sometimes considered trace elements, and sometimes not. Sodium is needed in large quantities, but the mineral is found so commonly in food, it is not generally necessary to take additional supplements. Various other elements found in food supplies may vary from holding no known nutritional value (such as silver) to being toxic (such as mercury).