Effect of Substituting Plant Protein for Animal-Protein on Cardiometabolic Risk: A Series of Systematic Reviews and Meta-Analyses of Controlled Feeding Trials to Provide Evidence-Based Guidance for Nutrition Guidelines Development

Vegetarian diets have been associated with a reduced risk of preventable diseases such as type 2 diabetes and cardiovascular disease. These effects may be mediated through direct or indirect pathways. Although the high intakes of nuts, legumes, dietary fibre, whole grains, and unsaturated plant oils have each individually been associated with lower risk of type 2 diabetes and cardiovascular disease, so too has the displacement of red meats, processed meats, and saturated animal fats. One of the most important considerations in moving from animal-based diets to more plant-based diets is the replacement of animal proteins (e.g. meat, fish, dairy, eggs) with vegetable proteins (e.g. legumes, nuts, and seeds). It is unclear whether this particular replacement alone results in advantages for metabolic and cardiovascular health. To improve evidence-based guidance for dietary guidelines and health claims development, we propose to conduct a series of systematic reviews and meta-analyses of the effect of plant-based protein in exchange for animal protein on blood lipids, glycemic control, blood pressure, body weight, uric acid, markers of non-alcoholic fatty liver disease (NAFLD), and kidney function and injury. The systematic review process allows the combining of the results from many small studies in order to arrive at a pooled estimate, similar to a weighted average, of the true effect. The investigators will be able to explore whether the effects of replacing animal-based protein for plant-based protein hold true across different sexes, age groups, and background disease states and whether the effect depends on the protein source, dose, or background diet. The findings of this proposed knowledge synthesis will help improve the health of Canadians through informing recommendations for the general public, as well as those at risk of heart disease and diabetes.