Lipid metabolism, inflammation, oxidative stress and endothelial function play important roles in the pathogenesis of cardiovascular disease (CVD), which may be affected by an imbalance in the n-6/n-3 polyunsaturated fatty acid (PUFA) ratio. This study aimed to investigate the effects of the n-6/n-3 PUFA ratio on these cardiovascular risk factors in rats fed a high-fat diet using plant oils as the main n-3 PUFA source. The 1:1 and 5:1 ratio groups had significantly decreased serum levels of total cholesterol, low-density lipoprotein cholesterol, and proinflammatory cytokines compared with the 20:1 group (p < 0.05). Additionally, the 20:1 group had significantly increased serum levels of E-Selectin, von Willebrand factor (vWF), and numerous markers of oxidative stress compared with the other groups (p < 0.05). The 1:1 group had a significantly decreased lipid peroxide level compared with the other groups (p < 0.05). Serum levels of malondialdehyde, reactive oxygen species and vWF tended to increase with n-6/n-3 PUFA ratios increasing from 5:1 to 20:1. We demonstrated that low n-6/n-3 PUFA ratio (1:1 and 5:1) had a beneficial effect on cardiovascular risk factors by enhancing favorable lipid profiles, having anti-inflammatory and anti-oxidative stress effects, and improving endothelial function. A high n-6/n-3 PUFA ratio (20:1) had adverse effects. Our results indicated that low n-6/n-3 PUFA ratios exerted beneficial cardiovascular effects, suggesting that plant oils could be used as a source of n-3 fatty acids to prevent CVD. They also suggested that we should be aware of possible adverse effects from excessive n-3 PUFA.

This study investigated the effects of blended oils with different n-6/n-3 polyunsaturated fatty acid (PUFA) ratios on the metabolic disorders and hepatic steatosis in high-fat diet-fed rats. The 1:1 group had significantly lower serum low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol (HDL-C), and lipoprotein lipase (LPL) levels than those of the Lard group. The 5:1 group had significantly lower serum LDL-C, LPL, and adiponectin (ADP) than those in the Lard group. Serum LDL-C, angiotensin II (Ang II), endothelin-1, LPL and ADP levels in the 1:1 and 5:1 groups were significantly lower than those in the normal control group. The 5:1 group had significantly lower serum ADP, Ang II, LPL and resistin levels than those in the 20:1 group. The 20:1 group had significantly higher serum TC, LDL-C, HDL-C, nitric oxide (NO), 3-nitrotyrosine, free fatty acid and LPL levels than those in the 1:1 ratio group. Blended oils with a low n-6/n-3 PUFA ratio improved metabolic disorders and hepatic steatosis by regulating lipid metabolism, adipokines, endothelial cell function, and liver lipid metabolism. Conversely, a high n-6/n-3 PUFA ratio had adverse effects on metabolic profiles in high-fat diet-fed rats.