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BJ Sonko1,6, AM Prentice2, WA Coward3, PR Murgatroyd4 & GR Goldberg5
1University of Colorado Health Sciences Center, Department of ediatrics, Denver, Colorado, USA
2MRC International Nutrition Group, Public Health Nutrition Unit, London School of Hygiene and Tropical Medicine, London, UK
3MRC Human Nutrition Unit, Cambridge, UK
4University of Cambridge, Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge, UK
5British Nutrition Foundation, London, UK
Correspondence to: BJ Sonko, University of Colorado Health Sciences Center, Department of Pediatrics, Campus Box C232, 4200 E. Ninth Ave, Denver, CO 80262, USA.
Email: Bakary.Sonko@UCHSC.edu
Guarantor: Dr BJ Sonko & Dr AM Prentice.
Contributors: Dr Sonko co-conceived the idea for the study and co-developed it into a study project. He was involved in subject recruitment, data collection and data analysis. He produced the first draft and co-refined it into the final draft. Dr Prentice co-conceived the idea and co-developed it into a study project. He was involved in data collection as well as data analysis. He commented on the first draft and also helped intellectually in the refinement of the final draft. Dr Coward co-developed the idea into a study project. He was involved in the mass spectrometry data analysis of the study. He commented on the draft and was involved in the refinement of the final draft. Dr Murgatroyd was involved in data collection, particularly in the calorimeter component of the study. He commented on the first draft as well as being involved in the refinement of the final draft. Dr Goldberg was involved in subject recruitment, data collection, commented on the first draft and was involved in the refinement of the final draft. All the contributors participated intellectually in the development of the paper.
6Formerly of Dunn Nutrition Group, c/o MRC Laboratories, Fajara, Banjul, The Gambia. Supported by the Nestle Foundation, Switzerland
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Objective: To determine dose-dependent relationship between ingested fat and its oxidation in the immediate post-prandial period in humans. Design: Subjects were randomly selected for the study at the Dunn Clinical Nutrition Centre, Cambridge, UK. Subjects ingested naturally enriched 13C corn-oil doses (range 20–140 g) in a whole-body indirect calorimeter, and were studied for 8 h. Ingested fat oxidation was estimated from the subject's breath 13C enrichment and total carbon dioxide production. Total fat and carbohydrate oxidation were estimated from non-protein oxygen and carbon dioxide exchanges. Endogenous fat oxidation was estimated as the difference between total fat and ingested fat oxidation. Results: The amount of fat dose oxidized was nonlinearly related to the amount ingested. On average, 25.6 2.7% of the mean fat dose was oxidized. A significant (r=-0.72, P<0.001) inverse correlation was found between the amount of fat dose and the proportion oxidized. Endogenous carbohydrate oxidation was negatively and significantly correlated to fat dose oxidized (r=-0.61, P<0.01), but it was not correlated to endogenous fat oxidation. Conclusions: There was a nonlinear relationship between amount of fat dose and its quantity that was oxidized in the immediate post-prandial period. The inverse relationship between the size of the fat load and the proportion that was oxidized post-prandially implies increased dietary fat storage beyond about 50 g in a normal resting adult. This has important implications for 13CO2-based studies. Sponsorship: This study was funded by the Nestle Foundation, Switzerland and the British Medical Research Council, UK. European Journal of Clinical Nutrition (2001) 55, 10–18
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