Micronutrient deficiency is defined as the sustained insufficient supply of vitamins and minerals needed for growth and development, as well as to maintain optimal health.

[4][5][6][7] The most commonly analyzed micronutrient deficiencies, and therefore the most prevalent, include[8] iodine, iron,[2] zinc,[2] calcium, selenium, fluorine, and vitamins A, B6,[9] B12,[10] B9 (folate)[2] and D,[8] with large variations between countries and populations.

Nonetheless, it has been well established that micronutrient deficiencies are major contributors to impaired growth and neurodevelopment, perinatal complications and increased risk of morbidity and mortality.

Early childhood micronutrient deficiency leads to stunted growth and impaired cognitive development, which in turn can translate into reduced work capacity, productivity and overall well-being during adulthood.

Micronutrients are distinguished from macronutrients (nitrogen, phosphorus, sulfur, potassium, calcium and magnesium) by the relatively low quantities needed by the plant.