β-oxidation of linoleate in obese men undergoing weight loss

Abstract

Background: In animals, the wholebody content and accumulation of linoleate can be measured and compared with its intake to determine linoleate β-oxidation. This method can also provide quantitative information about the β-oxidation of linoleate in humans. Objectives: The objectives of the study were to 1) use the wholebody fatty acid balance method to quantify wholebody 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 β-oxidation in obese humans. Design: 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 β-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. Wholebody loss of linoleate was 37 ± 18 mmol/d, or 28% of the level before weight loss. Combining the intake and wholebody loss of linoleate resulted in linoleate β-oxidation exceeding intake by 2.5-fold during the weight-loss period. Conclusions: All dietary linoleate is β-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.