Inverse Associations of Overall and Abdominal Obesity with Plasma N-3 Polyunsaturated Fatty Acids in Iranian Adults

Introduction: Obesity is a common health problem, which leads to diseases such as hypertension, cardiovascular diseases, hyperlipidemia, diabetes, gout, gall bladder and liver diseases, cancer, and depression. The prevalence of obesity has risen significantly across the world, especially in the Asia-Pacific region.Omega-3 is a polyunsaturated fatty acids with several beneficial effects on diseases such as diabetes, hypertension, rheumatoid arthritis, bipolar disorder, and asthma. The present study aimed to assess the levels of omega-3 fatty acids in subjects with various body mass indices (normal weight, overweight, and obese) and waist circumference (no risk, high-risk, and extremely high-risk). Methods: This cross-sectional study was conducted on 151 subjects, including 58 men and 93 women (age range: 18-65 years), who were randomly selected from the patients attending the nutrition clinics in Mashhad, Iran at 2014. The participants were divided into three groups based on the body mass index (BMI; normal weight, overweight, and obese) and waist circumference (WC; no risk, high-risk, and extremely high-risk). Plasma levels of omega-3 fatty acids were determined in the blood sample collected from the participants using the gas chromatography apparatus equipped with a flame ionization detector (GC-FID). The study protocol was approved by the Ethics Committee of Mashhad University of Medical Sciences (MUMS), and written informed consent was obtained from all the participants. Results: Alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) had inverse associations with overall obesity (P<0.001, P<0.001, and P<0.001, respectively) and abdominal obesity (P=0.02, P=0.005, and P<0.001, respectively). Moreover, ALA, EPA, and DHA were inversely correlated with BMI (P<0.001, P<0.001, P<0.001, respectively) and WC (P=0.001, P<0.001, P<0.001, respectively). The differences in the levels of ALA and DHA were not statistically significant between men and women, while women had significantly higher levels of EPA compared to men (P=0.02). Conclusion: According to the results, plasma omega-3 polyunsaturated free fatty acids were inversely associated with the anthropometric indices of obesity, including BMI and WC. It is recommended that further investigations be conducted to identify the possible mechanisms linking the levels of plasma omega-3 fatty acids with overall and abdominal obesity.