Micronutrients are essential dietary elements required by organisms in varying quantities to regulate physiological functions of cells and organs.^[1][2] Micronutrients support the health of organisms throughout life.^[3][4][5]

In varying amounts supplied through the diet, micronutrients include such compounds as vitamins and dietary minerals.^[3][6] For human nutrition, micronutrient requirements are in amounts generally less than 100 milligrams per day whereas, macronutrients are required in gram quantities daily.^[6] A multiple micronutrient powder of at least iron, zinc, and vitamin A was added to the World Health Organization's List of Essential Medicines in 2019.^[7] Deficiencies in micronutrient intake commonly result in malnutrition.^[3][8]

Inadequate intake of essential nutrients predisposes humans to various chronic diseases with some 50% of American adults having one or more preventable disease.^[3] In the United States, foods poor in micronutrient content and high in food energy make up some 27% of daily calorie intake.^[3] One US national survey (National Health and Nutrition Examination Survey 2003-2006) found that persons with high sugar intake consumed fewer micronutrients especially vitamins A, C,E and magnesium.^[3]

A 1994 report by the World Bank estimated that micronutrient malnutrition costs developing economies at least 5 percent of gross domestic product.^[9] The Asian Development Bank has summarized the benefits of eliminating micronutrient deficiencies as follows:

Along with a growing understanding of the extent and impact of micronutrient malnutrition, several interventions have demonstrated the feasibility and benefits of correction and prevention. Distributing inexpensive capsules, diversifying to include more micronutrient-rich foods, or fortifying commonly consumed foods can make an enormous difference. Correcting iodine, vitamin A and iron deficiencies can improve the population-wide intelligence quotient by 10–15 points, reduce maternal deaths by one-fourth, decrease infant and child mortality by 40 percent and increase people's work capacity by almost half. The elimination of these deficiencies will reduce health care and education costs, improve work capacity and productivity, and accelerate equitable economic growth and national development. Improved nutrition is essential to sustain economic growth. Micronutrient deficiency elimination is as cost-effective as the best public health interventions and fortification is the most cost-effective strategy.^[10]

Salt iodization is a major strategy for addressing iodine deficiency which is a major cause of mental health problems. In 1990, less than 20 percent of households in developing countries were consuming iodized salt.^[11] By 1994, international partnerships had formed in a global campaign for Universal Salt Iodization. By 2008, it was estimated that 72 percent of households in developing countries were consuming iodized salt,^[12] and the number of countries in which iodine deficiency disorders were a public health concern reduced by more than half from 110 to 47 countries.^[11]

Vitamin A deficiency is a major factor in causing blindness worldwide particularly among children.^[13] Global vitamin A supplementation efforts have targeted 103 priority countries. In 1999, 16 percent of children in these countries received two annual doses of vitamin A. By 2007, the rate increased to 62 percent.^[14]

Fortification of staple foods with vitamin A has uncertain benefits in reducing the risk of subclinical vitamin A deficiency.^[15]

Fortification of staple foods may improve serum zinc levels in the population. Other effects such as improving zinc deficiency, children's growth, cognition, work capacity of adults or blood indicators are unknown.^[16] Experiments show that soil and foliar application of zinc fertilizer can effectively reduce the phytate zinc ratio in grain. People who eat bread prepared from zinc-enriched wheat show a significant increase in serum zinc suggesting that the zinc fertilizer strategy is a promising approach to address zinc deficiencies in humans.

Plants tend not to use vitamins, although minerals are required.^[8][17]

Some seven trace elements are essential to plant growth although often in trace quantities.^{[citation needed]}

• Boron is believed to be involved in carbohydrate transport in plants; it also assists in metabolic regulation. Boron deficiency will often result in bud dieback.
• Chloride is necessary for osmosis and ionic balance; it also plays a role in photosynthesis.
• Copper, iron, manganese, molybdenum and zinc are cofactors essential for the functioning of many enzymes.^[19] For plants, deficiency in these elements often results in inefficient production of chlorophyll manifested in chlorosis.

• List of micronutrients
• Human nutrition
• Macronutrient (ecology)
• Dietary mineral (redirects to Mineral (nutrient))
• Silicon § Human nutrition
• Manganese deficiency (medicine)