18 November 2013
Non-communicable diseases (NCDs), such as heart diseases and diabetes, are a growing threat to public health and economies worldwide. Unlike communicable diseases, the root cause of NCDs typically lies in long-term exposure to risk factors, such as unhealthy food and lack of physical activity. Behavioural and dietary habits often develop at an early age and continue in adulthood. Therefore, ensuring a healthy and active childhood may prevent the risk of NCDs in adult life and alleviate the resulting burden placed on health care systems.
Major changes occurring in the global diet, coupled with increased inactivity, have led to a sharp increase in the rates of obesity in children in the past few decades, especially in developing countries. Governments around the world are taking action to support preventive interventions programmes to ensure that children receive good nutrition, thus preventing potential NCDs in the future. Such programmes include promotion of exclusive breastfeeding, school breakfast or lunch programmes, nutrition awareness campaigns, food fortification and sports promotion. The IAEA, through its technical cooperation (TC) programme, works with its Member States to assess the efficiency and effectiveness of these intervention programmes to ensure that governments’ efforts are having the desired effect. In particular, the IAEA helps countries improve the techniques used to assess infant feeding practices, measure body composition and physical activity.
Nutrition programmes are typically evaluated by comparing before and after data, which is collected through several different procedures to assess body composition as an indicator of nutritional status. Commonly used body composition assessment techniques include the use of Body Mass Index (BMI) which is based on height and weight, skinfold thickness measurement, and bioelectrical impedance analysis. However, body composition expressed in terms of fat and fat free mass provides a far more accurate and reliable picture of nutritional status than BMI or skinfold thickness. Stable isotope techniques can be used to provide a much more accurate and precise depiction of body composition than conventional techniques, being able to measure changes in fat and fat free mass over a relatively short period of time.
Stable isotopes are safe and non-radioactive, and are naturally present in our bodies at very low concentrations. To measure body composition, an accurately weighed dose of stable isotope-labelled water, called deuterium oxide, is drunk. This mixes with the water already in the body to increase the isotopic concentration slightly above normal. Body water, in the form of saliva or urine, is sampled before and after drinking the isotope labelled water. The enrichment in body water, together with knowledge of the amount of labelled water consumed, allows the calculation of the amount of lean (fat-free) mass and fat mass.Total daily energy expenditure can be estimated using the doubly labelled water technique, which involves drinking a mixture of deuterium and oxygen-18 labelled water and monitoring the elimination of the isotopes from the body over a two week period. This information can then be used by policy makers to develop and evaluate effective nutritional intervention programmes that will contribute to reducing the risk of NCDs in adult life.
The IAEA, through the TC programme, helps countries build capacity in stable isotope techniques to improve their capability to monitor and evaluate nutrition and physical activity interventions designed to address the global problem of increasing childhood obesity. TC projects have been carried out in Latin America, Africa and Asia and the Pacific regions. So far, more than twelve projects have been implemented in all three regions. Capacity to use deuterium dilution techniques to assess body composition has been established in 17 countries in Latin America and the Caribbean, 23 in Africa and 6 in Asia and the Pacific region.
As a result of 15 years of technical cooperation with the IAEA on nutritional studies, many Latin American countries now include body composition in their national nutrition surveys. In addition, the Institute of Nutrition of Central America and Panama (INCAP) was established as a centre of excellence to carry out research, training, and capacity building for prevention and management of CVD and related risk factors to reduce the burden of CVD in Mesoamerica.
TC projects carried out in other regions are yielding similar results. Projects have contributed to developing and evaluating interventions to curb the dramatic increase in childhood obesity in the Middle East, building capacities in Asia and the Pacific region and informing the design and improvement of interventions aimed at prevention and control of obesity and related health risks in Africa.