The essential fatty acid pathway is a metabolic pathway that converts the essential fatty acids, alpha linolenic acid (ALA, C18:3 (n-3)) and linoleic acid (LA, C18:2 (n-6)) to a number of short-lived hormone like substances called eicosanoids. Eicosanoids are regulators of cell activity and in particular they can regulate the immune and inflammatory responses by cells. Disruption of the pathway may therefore lead to irregular cell activity and possible deleterious health consequences. Many metabolic pathways in the body, particularly those to do with macronutrient metabolism, are regulated allosterically by insulin. This relates to the storage function of insulin as the primary anabolic hormone. The regulation of the energy storage and macronutrient metabolising pathways by insulin is a necessary control mechanism and functions well to maintain correct metabolic regulation. However, chronic elevations in insulin levels can have a deleterious impact on metabolic regulation.
The ability of insulin to detrimentally affect the essential fatty acid pathway has been studied. For example in one study1, researchers investigated the association between diabetes and the delta-5 and delta-6 enzymes from the essential fatty acid pathway. The delta-6 desaturase enzyme is responsible for the first step in the metabolism of ALA and LA and is the rate limiting step in the pathway. The delta-5 desaturase enzyme is required further down the pathway and is not rate limiting. The study involved analysis of a cohort of nearly 30,000 middle aged subject with type 2 diabetes. The results of the study showed that delta-5 desaturase activity was inversely associated with type 2 diabetes risk, whereas delta-6 desaturase activity was positively associated with type 2 diabetes risk. Attenuation of the association between the activity of these enzymes and diabetes risk occured by controlling for fatty liver accumulation, suggests that the metabolic syndrome, and therefore insulin resistance, may have been a causative factor.
Dr Robert Barrington’s Nutritional Comments: These results support other data that shows that elevated levels of insulin are inhibitors of the essential fatty acid pathway. This inhibiting effects was one of the key point highlighted by Barry Sears in his original Zone Diet book. Controlling insulin levels through a reduction in insulin resistance and improvements in insulin sensitivity is a pivotal factor in the optimisation of the essential fatty acid pathway. Regulating this pathway appropriately is pivotal because it is the pathway that ultimately controls cellular inflammation. High insulin levels can therefore lead to inflammation through disruption of the essential fatty acid pathway, through inhibition of the activity of delta-6 desaturase, and this may be a primary driver for Western lifestyle diseases that centre on the development of inflammation and the generation of free radicals. Consuming low glycaemic index carbohydrates and reducing total carbohydrate intake may be beneficial in this regard.
RdB
