Validation of deuterium-labeled fatty acids for the measurement of dietary fat oxidation during physical activity

Measurement of C-13-labeled fatty acid oxidation is hindered by the need for acetate correction, measurement of the rate of CO2 production in a controlled environment, and frequent collection of breath samples. The use of deuterium-labeled fatty acids may overcome these limitations. Herein, d(31)-palmitate was validated against [1-C-13]palmitate during exercise. Thirteen subjects with body mass index of 22.9 +/- 3 kg/m(2) and body fat of 19.6 +/- 11% were subjected to 2 or 4 h of exercise at 25% maximum volume oxygen consumption (VO2max). The d(31)-palmitate and [1-C-13] palmitate were given orally in a liquid meal at breakfast. The d(3)-acetate and [1-C-13]acetate were given during another visit for acetate sequestration correction. Recovery of d(31)-palmitate in urine at 9 h after dose was compared with [1-C-13] palmitate recovery in breath. Cumulative recovery of d(31)-palmitate was 10.6 +/- 3% and that of [1-C-13]palmitate was 5.6 +/- 2%. The d(3)-acetate and [1-C-13]acetate recoveries were 85 +/- 4% and 54 +/- 4%, respectively. When [1-C-13]acetate recovery was used to correct C-13 data, the average recovery differences were 0.4 +/- 3%. Uncorrected d(31)-palmitate and acetate-corrected [1-C-13]palmitate were well correlated (y = 0.96x + 0; P < 0.0001) when used to measure fatty acid oxidation during exercise. Thus, d(31)-palmitate can be used in outpatient settings as it eliminates the need for acetate correction and frequent sampling.-Raman, A., S. Blanc, A. Adams, and D. A. Schoeller. Validation of deuterium-labeled fatty acids for the measurement of dietary fat oxidation during physical activity.