Environmental Enteropathy (EE) is a global disorder which contributes to poor child growth, micronutrient deficiencies, and impaired responses to oral vaccines. There is evidence that EE is associated with malabsorption of zinc, but the effects on other intestinal functions are unknown. The principal function of the intestine is to digest and absorb nutrients from the luminal stream, and several biochemical processes are essential to this dominant function. These processes include digestion of proteins into amino acids and dipeptides, digestion of complex carbohydrates into monosaccharides, emulsification and digestion of lipids. Nutrients, including these macronutrients together with micronutrients such as elements and vitamins, are absorbed by epithelial cells using a very complex array of several hundred transporters. A considerable amount of research was carried out on nutrient digestion and absorption in the 1960s and 1970s, but much less has been done recently. Recent elucidation of the importance of EE in global health and nutrition has highlighted the lack of information on digestion and absorption in the world literature, and there is almost no information on the impairments of digestion and absorption related to EE in adults and children in low and middle income countries.

A clinical study of the ¹³C sucrose breath test (¹³C-SBT) and the ¹³C mixed chain triglyceride test (¹³C-MCTT), was conducted by Paul Kelly and colleagues (collaborating team). The results of the SBT show useful correlation between ¹³CO₂ in breath and three measures of intestinal dysfunction: villus height and surface area, mucosal sucrose-isomaltase expression by immunostaining, and sucrose activity measured ex vivo in biopsies. However, this test only measures mucosal disaccharidase activity. We now want to go on and find tests for other aspects of mucosal digestive/absorptive function.

The significance of this study is that impairments of digestive and absorptive function can be overcome, by using enzymatic supplements, by using specially modified feeds, and/or by providing additional specific nutrients to overcome absorptive defects. While we are developing these tests in adults, the longer term objective is to adapt them for use in children with growth faltering, and to define nutritional modifications which these children may need.