Micronutrients

Micronutrients are essential nutrients required by the human body in small amounts for growth, development, and health. They include vitamins and minerals, which support a wide range of physiological processes but are needed far less than macronutrients such as carbohydrates, proteins, and fats.

Vitamins are organic compounds required in small amounts and are either fat-soluble (A, D, E, K) or water-soluble (C and the B vitamins). Minerals are inorganic elements and are categorized as major minerals (needed in relatively larger amounts, such as calcium, potassium, and magnesium) and trace minerals (needed in smaller amounts, such as iron, zinc, iodine, selenium, copper, and manganese). Daily requirements are typically expressed in micrograms or milligrams for vitamins and milligrams or micrograms for minerals, often defined by dietary reference intakes.

Roles of micronutrients include energy metabolism, DNA synthesis, antioxidant defense, immune function, bone health, fluid and electrolyte balance, and neurotransmitter function. Examples: iron for oxygen transport, iodine for thyroid hormone production, calcium and vitamin D for bone health, and vitamins A, C, and E for vision and antioxidant protection; folate for DNA synthesis; vitamin B12 for nervous system function.

Sources and bioavailability vary. A varied diet of fruits, vegetables, grains, dairy, meat, fish, eggs, and legumes commonly provides micronutrients; fortified foods can help fill gaps. Interactions affect absorption (for example, vitamin C can enhance non-heme iron absorption; phytates can inhibit zinc and iron uptake). Some micronutrients can accumulate with high intake, particularly fat-soluble vitamins, whereas most water-soluble vitamins are excreted more readily.

Assessment and safety guidance rely on dietary reference intakes, including RDAs or AIs, EARs, and ULs to prevent deficiency and toxicity. Deficiency and excess can lead to diseases such as iron-deficiency anemia, scurvy, goiter, or bone disorders.