Dietary high oleic canola oil supplemented with DHA oil attenuates plasma PCSK9 levels in humans

Abstract

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a novel circulating protein, which plays an important role in regulation of cholesterol metabolism by promoting hepatic LDL receptor degradation. However, the action of dietary fat composition on PCSK9 levels remains unknown. A double‐blinded RCT, consisting of five 30‐d intervention periods, was conducted to investigate varying dietary oils on circulating PCSK9 levels in healthy humans. Treatments included 60 g/d of conventional canola oil (Canola), high oleic canola oil (CanoalOleic), high oleic canola/DHA oil blend (CanolaDHA), corn/safflower oil blend (CornSaff) and flax/safflower oil blend (FlaxSaff). PCSK9 levels using ELISA were assessed at the end of each phase. Lipid profiles (n=54) showed that CanolaDHA feeding resulted in the highest (p<0.05) serum total cholesterol (TC) and LDL‐C levels among all five treatments. CanolaDHA feeding also produced the lowest (p<0.05) plasma PCSK9 concentrations (204.5±9.6 ng/ml) compared to Canola (231.6±9.6 ng/ml) and CanolaOleic (230.2±9.6 ng/ml) diets. In CanolaDHA diet, PCSK9 levels correlated (r=0.35, p<0.01) with TC levels but not with LDL‐C levels. Results indicate that post‐diet response in PCSK9 may be altered with CanolaDHA diet. In conclusion, the elevated LDL‐C levels from a DHA oil treatment may not be deleterious as they are accompanied by a decline in PCSK9 levels. (Supported by the Canola Council of Canada and Growing Forward II program)