“Our study reports several novel findings that clarify our understanding of the metabolic and physiological responses associated with different dietary FA (fatty acid) classes,” wrote the authors in the British Journal of Nutrition.
Fatty acid ethanolamides (FAE), also referred to as nacylethanolamines, were identified in the 1970’s as lipid mediators derived from long chain fatty acids. They mediate biological activities such as activation of cannabinoid receptors, stimulation of fat oxidation and regulation of satiety.
Genetic variants may influence circulating FAE levels in humans, impacting obesity and metabolic disorders.
In the present study, researchers hypothesised that dietary oils with differing FA composition could lead to shifts in plasma FAE levels, and the gene-diet interaction may result in changes in body fat composition.
The study was conducted as part of the Canola Oil Multicenter Intervention Trial (COMIT) study, a dietary intervention in adults with abdominal obesity and at least one criterion for metabolic syndrome.
The research was backed in part by the Canola Council of Canada and the Flax Council of Canada.
130 participants completed the five phase intervention study. They were randomly assigned to receive 60 g per day of either conventional canola oil, high oleic canola oil, high oleic canola oil enriched with DHA (docosahexaenoic acid), flax/safflower oil blend or corn/safflower oil blend.
All oils were low in saturated fatty acids and the canola-based oils were rich in monounsaturated fatty acids whilst the safflower blends were rich in polyunsaturated fatty acids.
Each treatment phase was 30 days in duration and was separated by a four-week washout period. With the exception of the oils, the participants were served identical diets throughout the study period.
FA profile and FAE levels were analysed, subjects were genotyped for two selected SNP’s (single nucleotide polymorphisms) associated with FAE metabolism, and measures of body fat mass were obtained by dual-energy X-ray absorptiometry (DEXA) scanning.
Overall results showed that plasma FAE levels were modulated by dietary fatty acids and had a positive correlation to their individual precursor plasma FA levels.
No significant results for fat mass were observed apart from an increase in gynoid fat mass (fat around the hips and bottom) associated with elevated plasma docosahexaenoylethanolamide (DHEA) levels in response to Canola DHA intake.
The researchers found that polymorphism rs324420 in fatty acid amide hydrolase may modulate oleoylethanolamide (OEA) and DHEA which might influence body fat mass distribution.
OEA is of pharmaceutical interest because of its effects on the endocannabinoid system and appetite, and therefore has potential as an obesity treatment.
“This finding indicates that endogenous OEA from dietary OA (oleic acid) might play a role in reducing fat mass.
“Given the growing evidence for the importance of FAE in governing energy metabolism, the implications of these trial results could be substantial,” wrote the authors.
‘Underpinning the benefits of the Mediterranean diet’
Professor Peter Jones, one of the study's authors from the University of Manitoba and director at Richardson Centre for Functional Foods and Nutraceuticals, told Nutraingredients he was excited about the results he said had implications for the understanding of the health benefits of the Mediterranean diet.
“Olive oil, an important component of the Mediterranean diet, is rich in monounsaturated fat, which has recently been shown to be the precursor of an important regulatory substance called OEA.
"Increasing scientific evidence in animals demonstrates that OEA in organs and blood, formed from monounsaturated fats in the diet, results in suppression of appetite and enhancement of caloric expenditure. These data have led to speculation that consuming monounsaturated fat-rich diets results in the formation of OEA which in turn alters energy balance and causes body fat loss."
Jones said their findings “reinforce the existing notion that high monounsaturated fats drive weight loss through the OEA regulation system, providing a scientific underpinning for the benefits of the Mediterranean diet”.
Source: British Journal of Nutrition
Published online ahead of print, http://dx.doi.org/10.1017/S0007114515005425
“Interactions between dietary oil treatments and genetic variants modulate fatty acid ethanolamides in plasma and body weight composition”
Authors: S.Pu et al.