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The oxidation of fatty acids and other substrates in healthy men fed butterfat versus beef tallow MacDougall, Diane E.


To assess the influence of dietary fat composition on postprandial oxidation of dietary myristic acid (MA), palmitic acid (PA) and other substrates, healthy males (n=8) consumed prepared solid food diets containing 22% of energy as butter or tallow. Using a randomized cross-over design, subjects were prefed 11 day test diets which were identical in nutrient content except for the specific fat treatment. The diets provided 40%, 45%, and 15% of energy as fat, carbohydrate and protein, respectively, and were fed at a level equivalent to calculated energy requirements. On day 8 and day 11 of each diet cycle, a randomly assigned bolus of [1-¹³C]MA or [1-¹³C]PA (20 mg/kg body weight) was ingested with the breakfast meal. Hourly breath samples were collected for 9 hours thereafter and ¹³C0₂ enrichment was determined using isotope ratio mass spectrometry. Continuous respiratory gas exchange was also monitored and carbohydrate oxidation, fat oxidation and energy expenditure were determined. Treatment fat did not influence the fractional oxidation of dietary [1-¹³C]MA (% dose/9 hours; x±SEM; 7.1±1.0% and 8.6±0.9% after the butter and tallow meal, respectively) or [1-¹³C]PA (3.3±0.7% and 3.0±0.9% after the butter and tallow meal, respectively) (P

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