Undernutrition: the global scenario
Stunted linear growth has become the main indicator of childhood undernutrition, because of its prevalence in nearly all low or middle income countries, and its important consequences for health and development. According to 2011 global estimates of the United Nations (UN) more than 165 million children under 5 years (26%) were stunted (HAZ=height-for-age Z score > -2), 100 million children (16%) were underweight (WAZ=weight-for-age Z score > -2) and around 52 million (8%) were wasted (WHZ=weight-for-height Z score > -2).1 Figure 1 shows those countries where 90% of the world’s stunted children with the highest burden live.
Malnutrition is a global problem, with Africa and South-East and Central Asia most affected by the burden of undernutrition.
Infants, young children and pregnant and lactating women are the most vulnerable groups because of their relatively high nutritional requirements for growth and development.
Figure 1: The 34 countries with the highest burden of undernutrition1.
Global prevalence data on malnutrition have predominantly been collected and harmonized on children under five years of age. Prevalence data of malnutrition in school-aged children and in adolescent and pregnant women have been less frequently assessed. The nutritional status of school-aged children in low- and middle-income countries was reviewed in 2010.1 Available data show that malnutrition clearly is an issue in school-aged children across developing countries and countries in transition. The average prevalence of stunting was between 20% and 30% in all regions except Latin America. The median prevalence of underweight was 17%, with the highest mean prevalence in South-East Asia (39%) and the lowest in Latin America (8%). Thinness prevalence was around 35% in both Africa and South-East Asia.2
Worldwide, more than 2 billion people in the world suffer from micronutrient deficiencies with iron, vitamin A and iodine deficiency being most common. Together, these affect at least one third of the world’s population. Iron deficiency is the most prevalent of the three, with just over 2 billion people being anemic. Just under 2 billion have inadequate iodine status and 254 million preschool children are vitamin A deficient.3 In addition to these three micronutrients, zinc deficiency also has a large disease burden, but data on zinc status are limited.4 Table 1 shows estimates of the prevalence vitamin A, iodine, iron and zinc deficiency in children, pregnant women and all age groups, globally and per region.4
Folate, calcium and vitamin D deficiencies are also known to be prevalent with serious consequences for (fetal) growth and development.3,4 Several studies show that vitamin D deficiency is a global public health concern in all age groups.5,6
Overweight and obesity: the paradigm shifts
Both developed as well as, increasingly, developing countries struggle with the burden of overnutrition. Worldwide, the prevalence of overweight and obesity combined rose by 27.5% for adults and 47.1% for children between 1980 and 2013. This means that in 2013 over 2 billion people worldwide suffered from obesity or overweight. Since 1980, the prevalence of overweight and obesity in children and adolescents has increased in developed as well as developing countries. In developed countries from 16.9% to 23.8% in boys and 16.2% to 22.6% in girls, in developing countries from 8.1% to 12.9% for boys and 8.4% to 13.4% in girls.7
- The Lancet Nutrition Interventions Review Group, Executive Summary of The Lancet Maternal and Child Nutrition Series. 2013.
- C. Best, et al., The nutritional status of school-aged children: Why should we care? Food Nutr Bull, 2010. 31: p. 400-417.
- World Health Organization, Guidelines on food fortification with micronutrients. 2006.
- R.E. Black et al., Maternal and child undernutrition and overweight in low-income and middle-income countries. Lancet, 2013. 382(9890): p. 427–51.
- N.M. van Schoor NM and P. Lips, Worldwide vitamin D status. Best Pract Res Clin Endocrinol Metab., 2011. 25(4): p. 671-80.
- C. Palacios and L. Gonzalez, Is vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol. , 2013. S0960-0760(13): p. 00233-1.
- M. Ng et al., Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013. Lancet, 2014.