Intake of herring oil, but not of anchovy oil, resulted in a lower serum cholesterol concentration in male Zucker Diabetic Sprague Dawley rats

Patients with type 2 diabetes have increased risks for dyslipidaemia and subsequently for developing vascular complications. A recent meta-analysis found that cetoleic acid (C22:1n-11) rich fish oils resulted in lower cholesterol concentration in rodents. The aim was to investigate the effect of consuming fish oils with or without cetoleic acid on serum cholesterol concentration in diabetic rats and to elucidate any effects on cholesterol metabolism. Eighteen male Zucker Diabetic Sprague Dawley rats were fed diets containing herring oil (HERO) or anchovy oil (ANCO) or a control diet with soyabean oil for 5 weeks. The HERO diet contained 0·70 % cetoleic acid, with no cetoleic acid in the ANCO diet. The HERO and ANCO diets contained 0·35 and 0·37 wt% EPA + DHA, respectively. Data were analysed using one-way ANOVA. The serum total cholesterol concentration was 14 % lower in the HERO group compared with ANCO and Control groups (<i>P</i> = 0·023). The HERO group had a higher faecal excretion of bile acids (<i>P</i> = 0·0036), but the cholesterol production in the liver, the hepatic secretion of VLDL and the liver's capacity to take up cholesterol were similar to controls. The ANCO diet did not affect the serum cholesterol concentration, but the hepatic cholesterol biosynthesis, the clearance of lipoprotein cholesterol and the excretion of bile acids in faeces were higher than in the Control group. To conclude, consumption of herring oil, but not of anchovy oil, led to a lower cholesterol concentration in a type 2 diabetes rat model.