Effect ofn-3 PUFA supplementation at different EPA:DHA ratios on the spontaneously hypertensive obese rat model of the metabolic syndrome

Abstract

The increasing incidence of the metabolic syndrome (MetS), a combination of risk factors before the onset of CVD and type 2 diabetes, encourages studies on the role of functional food components such as long-chain n-3 PUFA as preventive agents. In the present study, we explore the effect of EPA and DHA supplementation in different proportions on spontaneously hypertensive obese (SHROB) rats, a model for the MetS in a prediabetic state with mild oxidative stress. SHROB rats were randomised into four groups (n 7), each supplemented with EPA/DHA at ratios of 1:1, 2:1 and 1:2, or soyabean oil as the control for 13 weeks. The results showed that in all the proportions tested, EPA/DHA supplementation significantly lowered total and LDL-cholesterol concentrations, compared with those of the control group. EPA/DHA supplementation at the ratios of 1:1 and 2:1 significantly decreased inflammation (C-reactive protein levels) and lowered oxidative stress (decreased excretion of urinary isoprostanes), mainly at the ratio of 1:2. The activity of antioxidant enzymes increased in erythrocytes, abdominal fat and kidneys, with magnitudes depending on the EPA:DHA ratio. PUFA mixtures from fish affected different MetS markers of CVD risk factors in SHROB rats, depending on the ratios of EPA/DHA supplementation. The activation of endogenous defence systems may be related to the reduction of inflammation and oxidative stress.

Protective role of n6/n3 PUFA supplementation with varying DHA/EPA ratios against atherosclerosis in mice

“…In our study, the lowest serum TC and LDL-C concentrations were observed in the DHA/EPA 2:1 group and the highest serum HDL-C concentration was observed in the DHA/EPA 1:1 group, which appeared to differ from the existing report that using more or equal amounts of EPA is better than using an excess of DHA for the control of dyslipidemia in metabolic syndromes [19]. Our findings implied that a higher DHA/EPA ratio is better for reducing serum "bad cholesterol" levels.…”

“…However, another report demonstrated that the levels of plasma CRP were significantly decreased by EPA/DHA supplementation at 1:1 and 2:1 ratios, but not at 1:2 ratio [19]. In this study, there was no significant difference in the levels of pro-and/or anti-inflammatory factors in serum and aortic tissues between the DHA/EPA groups, which again highlights the importance of the n6/n3 PUFA ratio.…”

“…Additionally, TC, TG, LDL-C, and HDL-C levels were not statistically significantly different among DHA/EPA groups (1:1, 2:1, and 1:2) in female Wistar rats [21], and the TC concentration was lower in the 2:1 and 1:2 groups compared to the 1:1 group in spontaneously hypertensive obese rats [19]. In our study, the lowest serum TC and LDL-C concentrations were observed in the DHA/EPA 2:1 group and the highest serum HDL-C concentration was observed in the DHA/EPA 1:1 group, which appeared to differ from the existing report that using more or equal amounts of EPA is better than using an excess of DHA for the control of dyslipidemia in metabolic syndromes [19].…”

“…But recently, the increasing evidence focused on the proportions of DHA and EPA on chronic disease in rat models [19][20][21][22], which implied that both n6/n3 ratios and DHA/EPA ratios should be considered simultaneously.…”

Researches on the Pharmacological Effects of Eicosapentaenoic Acid

“…As the decades passed, n-3 PUFAs have been developed as dietary supplements, and it is now widely accepted that n-3PUFAs are incorporated as structural components into cell membrane phospholipids in the blood and tissues, and they mediate an array of biological effects [2,3].…”