Magnetic Resonance Imaging-Portfolio Diet Study #7

Overview

Presently in Canada, 29% of deaths are due to cardiovascular disease (CVD), costing $20.9 billion annually. The investigators have, therefore, brought together an unique network of investigators at different stages in their careers with a range of disciplines (nutrition, cardiology, diabetes, imaging, physics, clinical trials, statistics, laboratory medicine, primary care, genetics, psychology, knowledge translation (KT), and epidemiology) and with international recognition , experience and connections, to undertake a multi-centre study which will test the ability of the dietary Portfolio PLUS approach over 3 years to reduce the progression of plaque build-up in the carotid artery as assessed by Magnetic Resonance Imaging (MRI) in individuals with hypercholesterolemia. The dietary portfolio of cholesterol-lowering foods (viscous fibres, soy protein, plant sterol and nuts) which has been proven in many of their studies to be an effective cholesterol-lowering diet will be further enhanced by increased levels of monounsaturated fats (MUFA) and low glycemic index foods. Will this enhanced dietary strategy (dietary Portfolio PLUS ) reduce the progression of carotid atheromatous lesions, LDL-C and blood pressure while reducing the number of hyperlipidemic individuals requiring statins?

As Western populations age and as body weight increases, the need for dietary strategies to reduce Coronary Heart Disease (CHD) risk continues. The investigators are now in a position to put together a dietary approach which will be a significant advance over current dietary advice for CHD risk reduction. The investigators believe this study using imaging and functional techniques is now needed to 1) demonstrate an improvement in estimated CHD risk based on anatomical changes rather than serum risk factors. 2) encourage popular uptake and clinical use of this combination dietary strategy and 3) stimulate a larger longer term trial with CHD events. Participants for this study will be recruited in 4 academic centres across Canada (Quebec, Toronto, Winnipeg and Vancouver). They will be in the low or moderate risk category based on the current Canadian Cardiovascular Society's (CCS) Guidelines 2012 and would normally be considered for initial treatment with lifestyle only. All participants will first be screened by ultrasound for the presence of plaque in the carotid arteries and will then be randomized to one of the 2 treatment arms: Portfolio Plus diet (test) or modified DASH diet (control), both given as routine clinical advice with follow up visits at 3-month intervals for 6 months and then twice yearly for the remainder of the 3 year trial. Prior to starting either diet, participants will undergo screening ultrasound examination of both right and left carotids to enable selection of those individuals whose intima-media thickness would be 5-30% below the cut point considered by the Mannheim Consensus as relevant arterial thickening to ensure a relatively low risk group, yet with some measurable arterial thickening. The main outcome will be MRI assessment of maximum vessel wall volume. This assessment will be repeated at year 3. It will be emphasized at the outset that both the dietary portfolio and the DASH-like diets have been associated with benefits in terms of cholesterol reduction to provide equal encouragement for those randomized to the test and control groups. Portfolio and DASH-like dietary advice will consist of half hour individual sessions with the dietitian at baseline, 3, and 6 months and then at 6-month intervals. Prior to starting each diet, instruction will be given on achieving the dietary goals. At follow-up visits, the participants' completed 7-day diet records will be discussed and the original advice reinforced. Every effort will be made to obtain study blood samples and carotid imaging data from all subjects at the designated times regardless of adherence to the dietary aspects of the study protocol. All subjects will be included in the intention-to-treat analysis.