A large proportion of the population in low- and middle-income countries lives in an environment characterized by poor water, sanitation and hygiene conditions, which contribute to growth retardation in children. This is due to adverse modification of intestinal processes, which leads to improper absorption of the nutrients necessary for growth and other functions. This disturbance, originally referred to as environmental enteropathy, is now widely called environmental enteric dysfunction (EED) to reflect its multifaceted manifestations and effects.
A new IAEA-coordinated research project, approved in November 2016, is expected to provide a non-invasive, stable-isotope-based tool for diagnosis of EED in order to understand more clearly how this specific gut-related dysfunction affects the growth and health of children over longer periods of time in low- and middle-income countries. Nine countries from both developed and low- and middle-income settings have received IAEA grants to participate in this project, as technical experts in the case of developed countries and as research implementers in the case of low- and middle-income countries.
“It is of paramount importance to develop accurate, field-based, non-invasive methods to diagnose the condition,” said Victor Owino, a nutrition scientist at the IAEA. Nuclear-based stable isotope techniques offer the advantage that they can be used to assess multiple aspects of EED. (See What is environmental enteric dysfunction?)
The project is studying the effect of EED on child growth and health in specific populations, using a stable isotope technique — the carbon-13 (13C) sucrose breath test. This method has previously been used to assess non-EED-specific intestinal function. The assessment was based on the utilization of naturally 13C-enriched sucrose (from maize).
Since maize and sugarcane are widely consumed in low- and middle-income countries and already contain a lot of 13C sucrose, natural enrichment may not be adequate. Therefore, the project will develop and test the usability of a more highly enriched 13C sucrose breath test.
The carbon-13 sucrose breath test is based on the simple principle that, in the intestine, sucrose is broken down by a brush border enzyme called sucrase into glucose and fructose. When these are oxidized for use by the body, carbon-13 dioxide (13CO2) and water are produced. In abnormal circumstances, as in EED, sucrase enzyme activity and therefore 13CO2 production may be reduced. In contrast, in normal circumstances, a strong and early release of 13CO2 in the breath following an oral dose of 13C sucrose indicates a healthy gut function.
