Type of Paper: Paper in a Series on Maternal and Child Undernutrition
Purpose: To define the prevalence of maternal and childhood undernutrition and to discuss the disease burden of undernutrition. Specifically, the paper includes both new analyses and previously published results on the prevalence of, risk factors for, and the disease burden of undernutrition.
- Malnutrition can take the form of undernutrition or overnutrition (e.g., obesity). This paper focuses on undernutrition.
- Includes stunting, wasting, or micronutrient deficiencies (i.e., deficiency of a vitamin or mineral).
- Is prevalent in low-income and middle-income countries.
- Is an important determinant in child health.
- Is generally caused by inadequate dietary intake and disease.
- Underlying causes of inadequate intake and/or disease include poverty, food insecurity, inadequate care, unhealthy environments, and lack of health services.
- Poverty is a particularly important cause of undernutrition.
Prevalence of Childhood Undernutrition:
- Prevalence data are from 2005 and include children under the age of 5 years living in developing countries (low- and middle-income countries). The new WHO Child Growth Standards were used to define undernutrition for these prevalence rates.
- Underweight: 20% of children under the age of 5 in developing countries are underweight
- The highest prevalence rates were in south-central Asia (33%) and eastern Africa (26%).
- Wasting: 10% of children under the age of 5 globally are wasted.
- The highest prevalence is in south-central Asia (16%).
- 3.5% have severe wasting (weight-for-height less than -3 z-scores).
- Stunting: 32% of children under the age of 5 in developing countries are stunted.
- The highest prevalence rates were in eastern Africa (50%) and middle Africa (42%).
- The largest number of stunted children (74 million) live in south-central Asia.
- Stunting is most prevalent among the poorest regions within countries.
- Overlap between stunting and severe wasting:
- The prevalence of severe wasting is highest at younger ages and declines by the age of 24 months.
- The prevalence of stunting increases gradually until about 24 months of age after which the prevalence remains steady.
- Therefore, there is limited overlap in stunting and wasting.
- In younger children, the overlap between stunting and severe wasting was 0-20%; in older children, this overlap was 50-60%.
Risk Factors for Undernutrition:
- Child feeding practices:
- Suboptimum breastfeeding increases the risk for mortality and morbidity. Exclusive breastfeeding under 6 months of age has the lowest risk for mortality and morbidity. As the amount of breastfeeding decreases compared to other liquids and solids in the diet, the risk for mortality and morbidity increases.
- Inadequate quantity and quality of complementary foods after 6 months of age increases the risk for stunting during the first 2 years of life.
- Quality complementary feeding includes both energy dense foods and frequent feedings.
- Poor children are at risk for consuming low quality diets with lower intakes of animal source foods, increasing the risk for undernutrition.
- Infectious disease:
- Infectious diseases, such as malaria, respiratory illness, and diarrhea, increase the risk for stunting.
- Diarrhea has a particularly strong effect on stunting. The risk for stunting increases with the number of diarrhea episodes.
Health Consequences of Undernutrition:
- Short-term consequences of undernutrition include mortality, morbidity, and disability.
- Long-term consequences of undernutrition include effects on adult size, intellectual ability, economic productivity, reproductive performance, and metabolic and cardiovascular disease.
- The risk for mortality increases significantly with the degree of undernutrition, whether identified by underweight, wasting, or stunting.
- The effects of undernutrition on mortality and the burden of disease were estimated for the year 2004.
- Mortality refers to the number of deaths.
- The burden of disease refers to the gap between the current health of a population and an ideal situation where everyone in the population lives into old age in full health.
- DALYs (disability-adjusted life-years) are used to measure the burden of disease and are defined by years of healthy life lost (i.e., combined years of healthy life lost due to either premature death or years lived with a disability).
- Undernutrition, including stunting, severe wasting, and low birth weight, was responsible for:
- 2.1 million deaths (21% of all deaths) in children under the age of 5 years.
- 21% of global DALYs in children under 5 years.
- Undernutrition, identified by stunting, severe wasting, and low birth weight, is the largest risk factor for global deaths and burden of disease in children under 5 years.
- Suboptimum breastfeeding, particularly non-exclusive breastfeeding during the first 6 months of life, is responsible for 1.4 million deaths and 10% of the global burden of disease in children under 5 years of age.
- Deficiencies of the micronutrients vitamin A and zinc contribute to the global burden of disease more so than other micronutrients.
Black RE, Allen LH, Bhutta ZA, et al. Maternal and child undernutrition: global and regional exposures and health consequences. The Lancet. 2008;371(9608):243-260.