Introduction
Chronic low grade or metabolic inflammation is a central condition in the pathogenesis of obesity-induced
insulin resistance. Murine models provide evidence to support that adipose tissue
is a primary site where activation of adipokines and inflammatory cascades leads to resistance
to insulin action. Overexpression of the pro-inflammatory cytokine MCP-1 in adipose tissue
induces whole-body insulin resistance [1] whereas inhibiting the expression of MCP-1 or its
receptor CCR-2, protects mice from developing high-fat-diet–induced insulin resistance [2].
Mice overexpressing adiponectin are also protected from developing high-fat diet–induced
insulin resistance [3]. Adipose tissue functions as a major regulator of fatty acid metabolism
due to its high storage capacity for fatty acids as triacylglycerols, i.e. approximately 15–35% of
body weight. Eicosapentaenoic acid (EPA) (20:5n3) and docosahexaenoic acid (DHA) (22: 6n-
3) are essential ω-3 fatty acids (FAs) that enhance beta-oxidation and up-regulate mitochondrial
biogenesis [4]. They are primarily found in cold sea fish and fish oil [5]. EPA and DHA
decreased fasting insulin and HOMA-IR in rats and prevented the development of insulin
resistance associated with high-fat and high-sucrose feeding in rodents [6]. In humans, longterm
fish oil or a combination of EPA/DHA supplementation delayed the progression of
metabolic syndrome to type 2 diabetes and reduced insulin resistance in some but not all stud