Module 3: Micronutrient Deficiencies

In addition to the essential macronutrients (carbohydrates, fats, and proteins) for survival, vitamins and minerals – also known as micronutrients – contribute to good health and are necessary for proper growth and development. Dietary diversity helps individuals receive a nutritionally-balanced intake of necessary vitamins and minerals. Yet, many poor households around the world face food insecurity resulting in micronutrient deficiencies that lead to serious health consequences.(1) While a variety of factors contribute to micronutrient deficiencies, women and children are the most vulnerable. 

The most visible forms of childhood malnutrition are stunting and wasting. Yet, when it comes to vitamin deficiencies, the manifestations of disease may be much less visible. The term “hidden hunger” is used to describe “chronic micronutrient deficiencies” as they exist in children who are not classified as malnourished according to measurements of stunting or wasting.(2) Clinical manifestations of vitamin and mineral deficiencies usually only begin to show when the condition is severe and has already led to serious health burdens. Without proper technology, human resources, or laboratory facilities, it is difficult to assess true population deficiencies, and it is usually determined based on the prevalence of resulting illness.(3)          

Associated Health Complications

Micronutrient deficiencies cause significant health complications, deficiency-related disorders, and increase the risk of mortality and burden of disease. For instance, vitamin A is important for proper immune function. Deficiencies in vitamin A increase the risk of childhood infections, such as pneumonia and diarrheal disease, and increase the risk of child mortality. Currently, vitamin A deficiency affects 30% of children under-five with the highest rates in sub-Saharan Africa (48%) and South Asia (44%).(4) Vitamin A deficiency is the leading cause of preventable blindness in children and also increases the risk of death from common childhood illnesses such as diarrhea and measles.(5) In pregnant women, vitamin A deficiency causes night blindness and may increase the risk of maternal mortality.(6) In 1991, 39% of children in low- and middle-income countries were vitamin A deficient and by 2013 that number had decreased to 29% due in significant part to WHO recommended supplementation with tablets twice per year.(7)

Iron deficiency mainly affects children and women of reproductive age. More than half of all children living in developing countries between 6 months and 2 years of age are deficient in iron, and about 40% of young women have iron deficiency anemia.(8) Symptoms include fatigue, nausea, developmental impairment, and a weakened immune system. During pregnancy, iron deficiency can be harmful to both mother and child, resulting in birth complications, increased risk of maternal mortality (contributing to about 20% of deaths), and impaired physical and mental development.(9) The manifestations of iron deficiency are subtle but can have heavy consequences. 

Iodine deficiency is especially harmful during pregnancy, since iodine is critical for fetal development. If mothers do not have adequate iodine intake, babies may develop a form of mental retardation called cretinism.(10) The clinical manifestation of iodine deficiency is goiter, a swelling of the thyroid gland.(11) Social and economic consequences of deficiency also include decreased average intellectual quotient among populations.(12) The primary strategy among both developed and developing countries to address iodine deficiency is the fortification of salt with iodine, and this has proven successful at reducing health problems related to deficiency. 
Another essential micronutrient during pregnancy is folic acid. Deficiency in folic acid creates risk of severe neural tube defects such as spina bifida and anencephaly in newborns. Supplementation during pregnancy can help prevent birth defects and anemia, as folic acid improves iron absorption in the body. 

Current Interventions

The World Bank identifies the management of micronutrient deficiencies as related to vitamins and minerals as:

“…one of the most extraordinary development-related scientific advances of recent years. Probably no other technology available today offers as large an opportunity to improve lives and accelerate development at such low cost and in such a short time.”(13) 

Micronutrient interventions such as supplementation and fortification strategies have demonstrated high cost-effectiveness.(14) It has been estimated that micronutrient interventions can reduce lost DALYs due to underweight by 17%, mortality by 12%, and stunting by 17%.(15) A cohort study assessing the effect of nutrition interventions showed that existing interventions have the potential to reduce the burden of child undernutrition by 25% in the 36 countries that are most affected.(16) Of current interventions, breastfeeding strategies and supplementation or fortification with vitamin A and zinc have the greatest potential in reducing the burden of child morbidity and mortality if implemented universally. Supporting the need for increased global awareness towards malnutrition and the issue of “hidden hunger,” the 2008 Copenhagen Consensus even prioritized malnutrition as one of the top health challenges, with micronutrient supplementation, fortification, and community-based nutrition promotion presented among the top solutions.(17)

Footnotes

(1) Black, R.E., Allen, L.H., Bhutta, Z.A, Caulfield, L.E., de Onis, M., Ezzati, M. et al. (2008). Maternal and child undernutrition: global and regional exposures and health consequences. The Lancet, 371: 243-260.

(2) Burchi, F., Fanzo, J. & Frison, E. (2011). The role of food and nutrition system approaches in tackling hidden hunger. International Journal of Environmental Research and Public Health, 8(2): 358-373. 

(3) Bhutta, Z.A., Ahmed, T., Black, R.E., Cousens, S., Dewey, K., Giugliani, E., et al. (2008). What works? Interventions for maternal and child undernutrition and survival. The Lancet, 371:417-440.  

(4) UNICEF (2017). Vitamin A deficiency. https://data.unicef.org/topic/nutrition/vitamin-a-deficiency/.

(5) Ibid.

(6) World Health Organization. Micronutrient deficiencies. http://www.who.int/nutrition/topics/vad/en/.

(7) Stevens, G. A., Bennett, J. E., Hennocq, Q., Lu, Y., De-Regil, L. M., Rogers, L., ... & Oehrle, S. P. (2015). Trends and mortality effects of vitamin A deficiency in children in 138 low-income and middle-income countries between 1991 and 2013: a pooled analysis of population-based surveys. The Lancet Global Health, 3(9), e528-e536.

(8) The Micronutrient Initiative. (2004) Vitamin and Mineral Deficiency: a global progress report. 

(9) WHO (2011). Micronutrient Deficiencies.

(10) Ibid.

(11) Ibid.  

(12) Centers for Disease Control and Prevention. (2018). Micronutrient Facts. https://www.cdc.gov/immpact/micronutrients/index.html.

(13) The World Bank. (1995). Enriching Lives: overcoming vitamin and micronutrient malnutrition in developing countries. 

(14) Ibid. 

(15) Bhutta, Z.A., Ahmed, T., Black, R.E., Cousens, S., Dewey, K., Giugliani, E., et al. (2008). What works? Interventions for maternal and child undernutrition and survival. The Lancet, 371:417-440.  

(16) Ibid.  

(17) Copenhagen Consensus 2008 (2008).