Effects of n-3 fatty acid supplements on cardiometabolic profiles in hypertensive patients with abdominal obesity in Inner Mongolia: a randomized controlled trial

Daily supplementation with n-3 fatty acid (FA) has been believed to be an adjunct or alternative to drug treatments to reduce blood pressure (BP) and triglyceride (TG) levels in western patients with high risk of cardiovascular disease. The BP-lowering effect of n-3 FA supplements among Chinese hypertensive patients has been reported in our previous 12-week, double-blind, randomized controlled trial (RCT), but the benefits on cardiometabolic profiles among obese Chinese populations are not well known. We therefore used the data from the previous RCT to investigate the effects of marine- and plant-derived n-3 FA supplements on cardiometabolic profiles in middle-aged and elderly Chinese hypertensive patients with abdominal obesity. In total, 108 eligible volunteers from Inner Mongolia, China were randomly assigned to three treatments for 12 weeks: fish oil (FO, n = 35, 2 g day⁻¹ eicosapentaenoic acid + docosahexaenoic acid), flaxseed oil (FLO, n = 39, 2.5 g day⁻¹ α-linolenic acid), and corn oil served as a control (CO, n = 34). BP, blood lipids, waist circumference (WC) and fasting glucose–insulin were measured at baseline and after 12-week intervention by using standard methods. Clustered cardiometabolic risk was expressed as a continuously distributed z-score calculated by standardizing and then summing WC, insulin, glucose, TG, HDL-cholesterol and BP values. The cardiometabolic risk scores were significantly lower in the FO group than in the CO group after the 12-week intervention (−0.41 ± 0.92 vs. 0.02 ± 0.95, p = 0.016), but not in the FLO group (−0.23 ± 1.02 vs. 0.02 ± 0.95, p = 0.109). For individual risk factors, compared with CO, FO significantly decreased LDL-cholesterol (−0.25 ± 0.78 mmol L⁻¹vs. −0.05 ± 0.65 mmol L⁻¹, p = 0.010), ApoB (−012 ± 0.28 mmol L⁻¹vs. −0.03 ± 0.23 mmol L⁻¹, p = 0.036), and WC (−1.58 ± 3.67 cm vs. −0.52 ± 3.27 cm, p = 0.031), whereas no significant difference was found between FLO and CO groups in LDL-cholesterol (p = 0.081), ApoB (p = 0.102) and WC (p = 0.093). The present findings suggest that marine n-3 FA intervention may improve the cardiometabolic traits in this Chinese hypertensive population comorbid with abdominal obesity.