Abstract
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-1 vs. -0.05 ± 0.65 mmol L-1, p = 0.010), ApoB (-012 ± 0.28 mmol L-1 vs. -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.
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Key Points
Almost half of hypertensive patients are overweight or obese in China, across all ages in men and women. Abdominal fat accumulations in patients with high blood pressure (BP) lead to an increased risk of cardiometabolic disorder, a cluster of metabolic abnormalities predictive of cardiovascular mortality. In previous research from this group, the supplementations with n-3 FA, both marine (fish oil, FO) and plant-based (flaxseed oil, FLO), caused a notable improvement in cardiometabolic traits in this Chinese hypertensive population comorbid with abdominal obesity. In the present RCT, patients treated with FO had a significantly decreased cardiometabolic risk score compared to those treated with corn oil (CO), but those treated with FLO did not. Fish oil derived n-3 FA resulted in marked improvements in LDL-C, Apo B and non-HDL-C as well as WC, but not in TG, HDL-C, and insulin sensitivity. Such findings may provide further evidence of its benefits in improving cardiometabolic traits in Chinese hypertensive patients with abdominal obesity. The observed reductions in Apo B levels by n-3 FA treatments probably resulted from a primary inhibition of VLDL synthesis, an enhanced direct clearance of VLDL remnants, or a combination of both these mechanisms. In this trial, the control diet perhaps contained more saturated fat than the fish oil diet during the supplements, thus LDL-C might have been lowered. Compared with other populations with known n-3 FA intake, baseline erythrocyte levels of EPA plus DHA in this study population (3.26%) were similar to that in North American population (<4%) with a western dietary pattern.