MEASUREMENT OF WHOLE-BODY ACETATE TURNOVER IN HEALTHY-SUBJECTS WITH STABLE ISOTOPES

Colonic fermentation of dietary fibres produces short-chain fatty acids (e.g. acetate, propionate). Measurements of whole body acetate turnover was used in order to estimate the production of colonic short-chain fatty acids in human subjects. However, higher flux rates for acetate have been reported in human studies with stable isotopes as compared to radioactive tracers. The reasons for this discrepancy are unclear. In this study, the stable isotope (1-C-13)acetate was used and a method was developed to measure its enrichment in plasma. Variations between and within assays were less than 5%. The standard curve was linear from 0.5% to 10% enrichment. When this tracer was infused for 160 min in six healthy volunteers, acetate turnover was found to be 7.5 +/- 1 mu mol kg(-1) min(-1), which is similar to data reported with radioactive tracers. We assumed that the higher flux rate previously observed with stable isotope tracers was related to differences in the physiological status of the subjects involved in these studies.