Minerals are inorganic chemical elements required by the human body for structural, regulatory, enzymatic, electrical and other physiological functions. Unlike vitamins, which are organic molecules, minerals are elements and cannot be destroyed by ordinary cooking in the same way that heat-sensitive vitamins can, although minerals can be lost when water containing dissolved minerals is discarded. Nutrition commonly distinguishes major minerals, required in comparatively larger amounts, from trace minerals, required in smaller quantities. Important functions include forming bone and teeth, maintaining fluid and electrolyte balance, enabling nerve transmission, supporting muscle contraction, carrying oxygen and serving as components or cofactors of enzymes and hormones. Minerals are obtained from food, water and, in some circumstances, supplements.
Mineral chemistry determines how minerals behave in food and in the body. Minerals can exist as ions, salts or components of organic molecules, and their absorption can depend on chemical form, food composition and physiological status. Calcium, magnesium, sodium and potassium participate substantially in electrolyte and structural functions, while iron, zinc, copper, selenium and iodine have specialised roles that can become critical even though required quantities are relatively small. Bioavailability is not necessarily proportional to the amount listed on a nutrition label. Chemical binding, intestinal conditions and interactions with other nutrients can increase or decrease absorption. The body also regulates absorption and excretion differently for different elements.
Minerals have particularly important roles in structural tissues and physiological signalling. Calcium and phosphate contribute to the mineral structure of bones and teeth, while calcium ions also participate in muscle contraction, neurotransmission and intracellular signalling. Sodium and potassium establish electrochemical gradients across cell membranes that are essential for nerve impulses and muscle function. Magnesium participates in hundreds of enzyme-dependent reactions and interacts closely with cellular energy metabolism. Iron is incorporated into haemoglobin and other proteins involved in oxygen transport and electron transfer. Iodine is required for synthesis of thyroid hormones. These functions illustrate why mineral deficiency can affect multiple organ systems.
Mineral balance is controlled through coordinated intestinal absorption, transport, storage and excretion. The kidneys are particularly important for regulating concentrations of several minerals and electrolytes in the blood. Hormonal systems can alter absorption and renal handling when the body senses changes in mineral status. Bone also serves as a major reservoir for certain elements, especially calcium and phosphate, allowing concentrations in extracellular fluid to be maintained within tightly regulated ranges. Regulation means that the amount consumed is not identical to the amount retained. A person may absorb only part of the mineral present in food, and the proportion retained can change according to physiological demand and nutritional status.
Interactions between minerals and other dietary components are nutritionally important. Phytate, found in many plant foods, can bind certain minerals and reduce their absorption, while fermentation, soaking, sprouting and other food-processing methods can alter phytate content and mineral availability. Vitamin C can enhance non-haem iron absorption, while certain dietary components can inhibit it. Calcium can interfere with absorption of some substances when consumed simultaneously in large quantities, and excessive intake of one mineral can sometimes disrupt the handling of another. These relationships mean that mineral nutrition cannot always be evaluated by examining each element independently. Overall dietary pattern, meal composition and physiological status matter.
Deficiency and excess are both possible. Iron deficiency can lead to iron-deficiency anaemia, iodine deficiency can impair thyroid hormone production and cause goitre, and inadequate calcium or vitamin D status can compromise bone health. Excessive sodium intake is associated with increased blood pressure in many people, while excessive exposure to certain trace elements can cause toxicity. Some minerals have relatively narrow ranges between adequate and excessive exposure, whereas others are more readily regulated. Deficiency may arise from inadequate intake, poor absorption, increased losses or increased requirements, while toxicity can arise from supplements, contaminated sources, occupational exposure or medical conditions affecting excretion.
Food composition and geography can influence mineral intake. Iodine availability in food can depend partly on soil and environmental conditions, which is one reason iodised salt has been used in many countries as a population-level intervention. Mineral content can also vary according to agricultural practices, soil composition, animal feed and food processing. Drinking water can contribute minerals such as calcium and magnesium. Unlike vitamins, minerals are elements and therefore are not destroyed by cooking, but they can move into cooking water and be discarded. Refining grains can remove mineral-rich outer layers, while fortification can restore or increase selected mineral concentrations.
Minerals are therefore a chemically diverse group of essential elements whose functions range from electrical signalling and enzyme activity to oxygen transport and skeletal structure. Their nutritional significance depends not only on absolute intake but also on chemical form, absorption, interactions, physiological regulation and excretion. The terms major and trace describe quantity requirements rather than importance; a trace mineral can be indispensable despite being needed in very small amounts. Accurate understanding also requires distinguishing nutritional minerals from contaminants that have no beneficial physiological role or become toxic at sufficient exposure. Mineral nutrition is consequently a balance between obtaining enough of each required element and avoiding excessive exposure.
