Influence of the C-13-enrichment of the habitual diet on a (CO2)-C-13 breath test used as an index of liver glycogen oxidation: A validation study inWestern Europe and Africa

A diet containing naturally C-13-enriched carbohydrate combined with a (CO2 )-C-13 breath-test analysis can be used to monitor liver glycogen oxidation in persons used to a diet low in C-13, e.g., the Western European diet. In this study, we evaluated this test principle further by changing the way w e label the glycogen pool. The C-13 enrichment of exhaled CO2 was studied i n two groups, one in Europe and one in Africa. The European group (n = 12) was accustomed to a diet low in C-13, and they went on a C-13-enriched stud y diet to identify liver glycogen. The African group (n = 6) was accustomed to a diet naturally high in C-13, and they went on a diet low in C-13. The basal C-13 abundance in exhaled CO2 was higher in the African group (1.087 9 At%; atmospheric 1.1 atom percent) than in the European group (1.0821 At% ). During the study period, the parameters for Liver glycogen oxidation-the (CO2)-C-13 enrichment plateau, the plateau duration, and the return to bas eline time-did not differ between groups. The abundance of (CO2)-C-13 in ex haled CO2 over time in the two groups was similar but inverse. This study c onfirms the use of a (CO2)-C-13 breath test to monitor liver glycogen oxida tion and demonstrates how to use such a test in persons accustomed to a die t high in C-13. (C) Elsevier Science Inc. 2000.