C-sucrose breath test for the non-invasive assessment of environmental enteropathy in Zambian adults.

OBJECTIVES

Environmental enteropathy (EE) is a subclinical disorder highly prevalent in tropical and disadvantaged populations and is thought to play a role in growth faltering in children, poor responses to oral vaccines, and micronutrient deficiencies. This study aims to evaluate the potential of a non-invasive breath test based on stable isotopes for evaluation of impaired digestion and absorption of sucrose in EE.

METHODS

We optimized a C-sucrose breath test (C-SBT) in 19 young adults in Glasgow, United Kingdom. In a further experiment (in 18 adults) we validated the C-SBT using Reducose, an intestinal glucosidase inhibitor. We then compared the C-SBT to intestinal mucosal morphometry, immunostaining for sucrose-isomaltase (SI) expression, and SI activity in 24 Zambian adults with EE.

RESULTS

Fully labeled sucrose (0.3 mg/kg) provided clear breath enrichment signals over 2-3 h in both British and Zambian adults, more than fivefold higher than naturally enriched sucrose. Reducose dramatically impaired C-sucrose digestion, reducing 4 h CO breath recovery by > 50%. Duodenal biopsies in Zambian adults confirmed the presence of EE, and SI immunostaining was present in 16/24 adults. The kinetics of CO evolution were consistently faster in participants with detectable SI immunostaining. Although sucrase activity was strongly correlated with villus height ( = 0.72; < 0.05) after adjustment for age, sex and body mass index, there were no correlations between C-SBT and villus height or measured sucrase activity in pinch biopsies.

CONCLUSION

A C-SBT was developed which was easy to perform, generated clear enrichment of CO in breath samples, and clearly reports sucrase activity. Further work is needed to validate it and understand its applications in evaluating EE.