Beta-oxidation of linoleate in obese men undergoing weight loss.
BACKGROUND
In animals, the whole-body content and accumulation of linoleate can be measured and compared with its intake to determine linoleate beta-oxidation. This method can also provide quantitative information about the beta-oxidation of linoleate in humans.


OBJECTIVE
The objectives of the study were to 1) use the wholebody fatty acid balance method to quantify whole-body concentrations of linoleate in humans, 2) estimate the distribution of linoleate between adipose and lean tissue, and 3) assess the effect of weight loss on linoleate stores and beta-oxidation in obese humans.


METHODS
Nine healthy obese men underwent supervised weight loss for 112 d (16 wk). Magnetic resonance imaging data and fatty acid profiles from fat biopsies were both used to determine linoleate stores in adipose and lean tissue and in the whole body. Linoleate beta-oxidation was calculated as intake - (accumulation + excretion).


RESULTS
Mean weight loss was 13 kg and linoleate intake was 24 +/- 6 mmol/d over the study period. Whole-body loss of linoleate was 37 +/- 18 mmol/d, or 28% of the level before weight loss. Combining the intake and whole-body loss of linoleate resulted in linoleate beta-oxidation exceeding intake by 2.5-fold during the weight-loss period.


CONCLUSIONS
All dietary linoleate is beta-oxidized and at least an equivalent amount of linoleate is lost from the body during moderate weight loss in obese men. The method studied permits the assessment of long-term changes in linoleate homeostasis in obese humans and may be useful in determining the risk of linoleate deficiency in other conditions.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Canada. s.cunnane@utoronto.ca
S C
SC
Cunnane
R
R
Ross
J L
JL
Bannister
D J
DJ
Jenkins
D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D001835:Body Weight / Q000187:drug effects; D002788:Cholesterol Esters / Q000032:analysis; D002149:Energy Intake; D015444:Exercise; D005231:Fatty Acids, Unsaturated / Q000032:analysis*; D006706:Homeostasis; D006801:Humans; D019787:Linoleic Acid / Q000008:administration & dosage / Q000172:deficiency / Q000378:metabolism* / Q000493:pharmacokinetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism*; D010084:Oxidation-Reduction; D014018:Tissue Distribution; D015431:Weight Loss / Q000187:drug effects
D002788:Cholesterol Esters; D005231:Fatty Acids, Unsaturated; D019787:Linoleic Acid