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.
Cunnane
S C
SC
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Canada. s.cunnane@utoronto.ca
Ross
R
R
Bannister
J L
JL
Jenkins
D J
DJ
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