Mineral (nutrient)

In the study of nutrition, a mineral is defined as a chemical element. Minerals are one of the four essential nutrient groups. The other three groups are vitamins, essential fatty acids, and essential amino acids. While many chemical elements exist, only a specific set is essential for supporting human biochemical processes. These elements serve vital structural and functional roles within our bodies.

Minerals move through the environment via a specific biological chain. It begins when plants obtain minerals from the soil. Animals then ingest these plants, which moves the minerals up the food chain. Some larger organisms even practice geophagia, which is the consumption of soil. Others might use mineral resources like salt licks to meet their needs. For a mineral to be useful, it must be bioavailable. This means it must be soluble or easily extractable so the organism can absorb it. For example, molybdenum is essential, but metallic molybdenum provides no nutritional benefit. Instead, humans must consume molybdates found in foods like legumes.

Scientists categorize minerals based on the quantity the body requires. The five major minerals include calcium, phosphorus, potassium, sodium, and magnesium. Calcium is the most abundant mineral in an adult. It makes up about 1.5% of body weight, ranging from 920 to 1200 grams. Most of this calcium is stored in bones and teeth. Phosphorus is also a major component, making up about 1% of body weight. It is found in bones, cells, and molecules like DNA and ATP. Together, these major minerals and others like potassium and sodium form the bulk of our mineral needs.

Beyond the major minerals, the body requires trace elements. These are needed in much smaller amounts to facilitate specific functions. The generally accepted trace elements include iron, chlorine, cobalt, copper, zinc, manganese, molybdenum, iodine, selenium, and bromine. There are also about 18 ultratrace minerals. These comprise only about 0.15% of the body, totaling roughly 100 grams for an average person. While most minerals are common on land, some like sodium and iodine are also found in the ocean.

Each mineral performs a distinct biochemical job. Iron is required for proteins like hemoglobin, which prevents anemia. Zinc is a component of many enzymes, such as carbonic anhydrase, which helps with exhalation. Iodine is necessary for the synthesis of thyroid hormones. Magnesium is required for processing ATP, which is how cells manage energy. Even cobalt plays a role, though it is only available to animals after bacteria process it. These elements act as co-factors, meaning they help enzymes perform their chemical tasks.

Historical and scientific debate sometimes surrounds these elements. For instance, scientists disagree on whether chromium is an essential nutrient. The United States and Japan classify it as essential. However, the European Food Safety Authority did not agree after a 2014 review. This is because no chromium-containing biochemical has been purified yet. This demonstrates that defining "essential" requires finding a specific, testable function within a biomolecule. Some elements, like silicon, may only be needed in traces or not at all.

Maintaining the correct balance is a matter of strict limits. Health authorities set a Recommended Dietary Allowance (RDA) and an Upper Limit (UL). The UL is the maximum amount considered safe to consume. For example, the US sets the UL for calcium for adults over 70 at 2,000 mg. If you exceed these limits, it can be dangerous. Interestingly, magnesium is an anomaly. The UL for magnesium is 350 mg, which is lower than the recommended daily intake for men. This specific limit applies to taking magnesium as a supplement, as it can cause diarrhea if taken all at once.

Minerals are deeply connected to the broader systems of life on Earth. Plants and animals use very similar enzymes to process these elements. For example, legumes host a specific enzyme called nitrogenase that contains molybdenum. Humans do not have this. Similarly, many animals use iron in hemoglobin to transport oxygen, but plants do not rely on this method. Understanding these chemical requirements allows us to improve agriculture through tailored fertilizers. It also helps us design better diets and supplements to support human metabolism.