Shockingly, malnutrition remains a dominant cause of mortality, morbidity and lost potential in today’s children. In 2017, more than 1 in 5 children did not achieve their growth potential and were at risk of the associated long-term deficits in cognitive development. Stunting affects almost 40% of children in South Asia and the number of stunted children in Africa is rising. More than 1 in 14 of the world’s children are wasted. Forty-five percent of all deaths in under-fives are attributable to undernutrition. Meanwhile, overweight affects 1 in 20 of the world’s children. One in four overweight children live in Asia and numbers are expected to increase. Management of severe acute malnutrition (SAM) is a huge challenge in low resource healthcare settings and mortality rates remain high. Current interventions to prevent malnutrition have limited impact. More effective prevention and treatment of malnutrition is needed urgently.

Definitions

The two main manifestations of undernutrition based on anthropometry, the measurement of body size and proportions in humans, are shown in Figure 1. Compared with a child of the same age with normal anthropometric indices, impaired linear growth over a protracted period (“chronic malnutrition”) in the child on the right has caused stunting with low height-for-age but weight-for-height remains in the normal range. Acute malnutrition has resulted in wasting in the child in the middle with low weight-for-height and but normal height-for-age. Most countries have endorsed the WHO 2006 child growth standards which compare a child’s size to average values derived from healthy children using standard deviation or z-scores. A z-score below -3 for the median reference value (e.g. for height-for-age or weightfor-height) signifies severe undernutrition whilst a z-score between -3 and -2 signifies moderate undernutrition. Accurate measurement of weight and height is difficult. For community surveys of acute malnutrition, WHO recommends measurement of mid-upper arm circumference (MUAC) which is easier to measure and interpret. MUAC is similar in boys and girls and is relatively constant from 6 months to 5 years avoiding the requirement to calculate exact age. MUAC 115mm to less than 125mm signifies moderate and less than 115mm severe wasting. Severe acute malnutrition (SAM) is also diagnosed in children with nutritional oedema (pitting oedema of both feet). Finally, although recent data are scarce, deficiencies of one or more key micronutrients such as iron, iodine, zinc and vitamin A likely affect 1 in 3 of the world’s population and are often referred to as “hidden hunger”.