Effect of high polyphenol extra virgin olive oil on markers of cardiovascular disease risk in healthy Australian adults (OLIVAUS): a protocol for a double-blind randomised, controlled, cross-over study

Background: Previous clinical studies have suggested that high polyphenol extra virgin olive oil (EVOO) provides a superior cardioprotective effect compared to low polyphenol olive oil. However, further studies are required to replicate these results in non-Mediterranean populations. Aim: To investigate the effect of high polyphenol EVOO versus low polyphenol olive oil with known polyphenol composition on markers of cardiovascular disease risk in a healthy non-Mediterranean cohort. Methods: In a double-blind randomised cross-over trial, the present study will examine the effect of high polyphenol EVOO versus low polyphenol olive oil in 50 healthy participants. Each intervention phase will be 3 weeks long with a 2-week washout period between each phase. Outcomes to be assessed include HDL cholesterol efflux, oxidised LDL, blood lipids, C-reactive protein, arterial stiffness, blood pressure and cognitive function. Dietary intake, physical activity levels and anthropometry will also be collected. Discussion: Because of the rigorous trial design, novel and clinically relevant outcomes, the use of a well-characterised EVOO, and, in contrast to the current literature, the non-Mediterranean study population, the present study will provide a significant contribution to the understanding of the clinical importance of polyphenol intake in the Australian sociocultural context.