The scale of the malnutrition problem
Malnutrition encompasses undernutrition, micronutrient deficiencies and overweight/obesity (6). Suboptimal food intake over time and/or infectious diseases in children can result in stunted growth, while acute reduction in food intake and/or severe infectious diseases lead to wasting.
Around 155 million children below five years of age (23 %) are stunted, whereas 52 million (7.7 %) are wasted (7). The global prevalence of stunting was 33 % ten years ago, and has thus decreased substantially (7). However, most of this progress has taken place in South America and Southeast Asia. Especially in Sub-Saharan Africa and South Asia, levels of stunting and wasting continue to be very high. Gains in reducing undernutrition have been reversed in some countries by man-made and natural disasters. Climate change will lead to lower crop yields and food insecurity in vulnerable areas, and this is expected to cause increases in hunger and undernutrition (8).
Concurrently, worldwide rates of obesity are rising (9), caused by energy-dense, nutrient-poor diets and reduced physical activity. The consequence is a rapid rise in cardiovascular diseases, diabetes, and some cancers (10). These diseases are among the leading causes of death globally, and increasing rapidly in low- and middle-income countries (9). Unhealthy diets constitute the largest risk factor responsible for the global burden of disease (11).
The Lancet series not only described the scale and severity of the malnutrition problem, but also recommended evidence-based strategies to prevent and treat malnutrition (12–14). These strategies reflect the complex web of causes of malnutrition at different levels of society (individual, household, community and policy level). The Lancet series, and other more recent reports, emphasise the importance of integrating and promoting nutritional considerations and goals across sectors such as health, food production, water and sanitation, social protection and education (14).
The root causes of malnutrition are poverty, discrimination and inequalities. Malnutrition has a strong social gradient, whereby poor and marginalised groups typically experience the highest rates. Children are by far the most vulnerable to malnutrition, with their high nutritional needs and dependence on others for receiving food. Adolescent girls and pregnant and lactating women are also vulnerable to malnutrition.
At the second International Conference of Nutrition in 2014, the world’s leaders described the main nutritional challenges and reached agreement on how to solve them (15, 16). As a follow-up to the conference, the UN Decade of Action on Nutrition was declared in 2016 (17).