Is there dietary macronutrient malabsorption in children with environmental enteropathy?

Assessing the digestive and absorptive capacity of the gastro-intestinal tract (GIT) using minimally- or non-invasive methods, particularly in children, has been difficult owing to the complex physiology and variability in functional measurements. However, measuring GIT function is increasingly important with the emerging relevance of childhood environmental enteropathy (EE) as a mediating factor in linear growth faltering, severe acute malnutrition, poor oral vaccine uptake and impaired cognition. In EE, sub-optimal nutrient digestion and absorption (malabsorption) forms the critical link to the conditions mentioned above. The present narrative review discusses probable mechanisms that can cause malabsorption of macronutrients, along with mechanistic and experimental evidence, in children (if not, in adults) with EE. The strengths and limitations of the human experimental studies are examined in relation to a battery of existing and potential tests that are used to measure malabsorption. From the available studies conducted in children, lactose and fat malabsorption are more likely to occur in EE. Breath tests (non-invasive) measuring carbohydrate (¹³C-starch/sucrose/lactose), fat (¹³C-mixed triglyceride) and dipeptide (benzoyl-L-tyrosyl-L-1-¹³C-alanine) malabsorption with modifications to the existing protocols seem suitable for use in children with EE. Future research should focus on understanding the degree of macronutrient malabsorption using these tests, in different settings, and link them to functional outcomes (such as growth, muscle strength, cognition).