Micronutrients are essential to sustain life and for optimalphysiological function. Widespread global micronutrientdeficiencies (MNDs) exist, with pregnant women and theirchildren under 5 years at the highest risk. Iron, iodine, folate,vitamin A, and zinc deficiencies are the most widespreadMNDs, and all these MNDs are common contributors to poorgrowth, intellectual impairments, perinatal complications,and increased risk of morbidity and mortality. Iron deficiencyis the most common MND worldwide and leads to microcyticanemia, decreased capacity for work, as well as impairedimmune and endocrine function. Iodine deficiencydisorder is also widespread and results in goiter, mental retardation,or reduced cognitive function. Adequate zinc isnecessary for optimal immune function, and deficiency is associatedwith an increased incidence of diarrhea and acuterespiratory infections, major causes of death in those <5years of age. Folic acid taken in early pregnancy can preventneural tube defects. Folate is essential for DNA synthesis andrepair, and deficiency results in macrocytic anemia. VitaminA deficiency is the leading cause of blindness worldwide andalso impairs immune function and cell differentiation. Single MNDs rarely occur alone; often, multiple MNDs coexist. Thelong-term consequences of MNDs are not only seen at theindividual level but also have deleterious impacts on theeconomic development and human capital at the countrylevel. Perhaps of greatest concern is the cycle of MNDs thatpersists over generations and the intergenerational consequencesof MNDs that we are only beginning to understand.Prevention of MNDs is critical and traditionally has been accomplishedthrough supplementation, fortification, andfood-based approaches including diversification. It is widelyaccepted that intervention in the first 1,000 days is critical tobreak the cycle of malnutrition; however, a coordinated, sustainablecommitment to scaling up nutrition at the globallevel is still needed. Understanding the epidemiology ofMNDs is critical to understand what intervention strategieswill work best under different conditions.