Background: Bilberries from Sweden, rich in polyphenols, have shown cholesterol-lowering effects in small studies, and the cholesterol-lowering properties of oats, with abundant beta-glucans and potentially bioactive phytochemicals, are well established. Both may provide cardiometabolic benefits for patients with manifest chronic cardiometabolic disease, such as type 2 diabets mellitus (T2DM) and myocardial infarction (MI). However, large studies of adequate statistical power and appropriate duration are needed to confirm clinically relevant treatment effects. No previous study has evaluated the potential additive or synergistic effects of bilberry combined with oats on cardiometabolic risk factors.

Design: This is a double-blind, randomized, placebo-controlled clinical trial. Our primary objective is to assess cardioprotective effects of diet supplementation with dried bilberry and with bioprocessed oat bran, with a secondary explorative objective of assessing their combination, compared with a neutral isocaloric reference supplement, for patients diagnosed with T2DM and/or MI. Patients will be randomized 1:1:1:1 to a three-month intervention. The primary endpoint is the difference in LDL cholesterol change between the intervention groups after three months. The major secondary endpoint is exercise capacity at three months. Other secondary endpoints include plasma concentrations of biochemical markers of inflammation, glycaemia, and gut microbiota composition after three months. Implications: Secondary prevention after cardiometabolic disease, including T2DM and MI, has improved during the last decades but diabetes complications, readmissions and cadiovascular related deaths following these conditions remain large health care challenges. Controlling hyperlipidemia, hyperglycaemia, hypertension and inflammation is critical to preventing (new) cardiovascular events, but novel pharmacological treatments for these conditions are expensive and associated with negative side effects. If bilberry and/or oat, in addition to standard medical therapy, can lower LDL cholesterol and inflammation more than standard therapy alone, this could be a cost-effective and safe dietary strategy for secondary prevention in high-risk patients or risk prevention in subjects with T2DM.