Introduction
Obesity is one of the most important inflammatory diseases and its prevalence is increasing across the world (1). Obesity and overweight are associated with increased risk of several chronic disorders, and certain types of cancers (2).
It has been found that expression and secretion of adiponectin within the adipose tissue decreases in obese individuals (7). Adiponectin is the most prevalent adipokine which has beneficial effects on metabolism, fatty acids catabolism, low density lipoprotein cholesterol (LDL-C) oxidation, insulin sensitivity and suppression of inflammation (5, 6). Moreover, leptin has a energy balance regulation role, various hormonal functions as well as highly correlated to body fat mass(8).
Flaxseed or linseed (Linum usitatissimum L. seed) known as a functional food contains healthy components such as alpha linolenic acid (ALA), lignans, dietary fibers and a variety of antioxidants and phytoestrogens (12, 13).
Flaxseed lignans has numerous health benefits. For instance, it can regulate expression and secretion of adipokines such as adiponectin and leptin (14-17). It has been shown that ALA has anti-inflammatory, antithrombotic and anti-arrhythmic effects (16, 18, 19). ALA can deposit in adipose tissue where it may affect adipose tissue function and adipokine secretion (7). Besides ALA, flaxseed is a rich source of phytoestrogens (lignan) with potential benefits including cardio-protective and endocrine regulation effects (20, 21). These components are proposed to modify blood lipids levels mainly through regulating the gene expression of enzymes involved in the fatty acids metabolism (22-24). Previous studies in experimental models found an attenuating effect of flaxseed supplementation on serum lipids abnormalities and adiponectin and leptin secretion (25-28). However, the findings from clinical trials are conflicting(29, 30).
Therefore, in order to find the beneficial effects of whole flaxseed supplementation as an adjunct therapy to balanced diet on serum adipokines, body weight, Waist Circumference (WC) and lipid levels, we conducted the present trial on overweight or obese women.