Differential oxidation of individual dietary fatty acids in humans.
BACKGROUND
Dietary fatty acids that are more prone to oxidation than to storage may be less likely to lead to obesity.


OBJECTIVE
The aim of this study was to determine the effect of chain length, degree of unsaturation, and stereoisomeric effects of unsaturation on the oxidation of individual fatty acids in normal-weight men.


METHODS
Fatty acid oxidation was examined in men consuming a weight-maintenance diet containing 40% of energy as fat. After consuming the diet for 1 wk, subjects were fed fatty acids labeled with (13)C in the methyl or carboxyl position (10 mg/kg body wt). The fatty acids fed in random order were laurate, palmitate, stearate, oleate, elaidate (the trans isomer of oleate), linoleate, and linolenate blended in a hot liquid meal. Breath samples were collected for the next 9 h and the oxidation of each fatty acid was assessed by examining liberated (13)CO(2) in breath.


RESULTS
Cumulative oxidation over the 9-h test ranged from a high of 41% of the dose for laurate to a low of 13% of the dose for stearate. Of the 18-carbon fatty acids, linolenate was the most highly oxidized and linoleate appeared to be somewhat conserved. (13)C recovery in breath from the methyl-labeled fatty acids was approximately 30% less than that from the carboxyl-labeled fatty acids.


CONCLUSIONS
In summary, lauric acid is highly oxidized, whereas the polyunsaturated and monounsaturated fatty acids are fairly well oxidized. Oxidation of the long-chain, saturated fatty acids decreases with increasing carbon number.
DeLany
J P
JP
Pennington Biomedical Research Center, Baton Rouge, LA 70808-4124, USA. delanyjp@mhs.pbrc.edu
Windhauser
M M
MM
Champagne
C M
CM
Bray
G A
GA
D000328:Adult; D001944:Breath Tests; D002153:Calorimetry, Indirect; D002247:Carbon Isotopes; D004041:Dietary Fats / Q000378:metabolism*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007850:Lauric Acids / Q000378:metabolism; D016014:Linear Models; D019787:Linoleic Acid / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D019301:Oleic Acid / Q000378:metabolism; D009829:Oleic Acids; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D019308:Palmitic Acid / Q000378:metabolism; D010865:Pilot Projects; D015203:Reproducibility of Results; D013229:Stearic Acids / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000378:metabolism
D002247:Carbon Isotopes; D004041:Dietary Fats; D005227:Fatty Acids; D007850:Lauric Acids; D009829:Oleic Acids; D013229:Stearic Acids; D017962:alpha-Linolenic Acid; C030358:lauric acid; D019301:Oleic Acid; D019308:Palmitic Acid; C011459:elaidic acid; C031183:stearic acid; D019787:Linoleic Acid