Effect of butter compared with tallow consumption on postprandial oxidation of myristic and palmitic acids

To assess the influence of dietary fat composition on rates of oxidation of dietary myristic (MA) and palmitic (PA) acids, eight healthy males consumed prepared solid-food diets for 11 d with 40% of total energy as fat. Fifty-five percent of the energy obtained in the form of fat was provided as butter or beef tallow. On days 8 and 11 of each diet cycle, 20 mg/kg body wt of either [[1.sup.-13] C]MA or [[1.sup.-13]C]PA was ingested with breakfast. Hourly breath samples were collected over 9 h thereafter and [sup.13][CO.sub.2] enrichments were determined by using isotope-ratio mass spectrometry. The percentage of [sup.13]C]MA appearing in breath carbon dioxide over 9 h was more than twofold that of PA (P