The Effects of Red Meat Intake on Cardiometabolic Disease Outcomes in Adults

  To improve cardiometabolic health, omnivores are often recommended to simultaneously adopt a healthy dietary pattern with an emphasis on increasing intakes of plant-based proteins and decreasing intakes of red and processed meats. However, the totality of observational and experimental results inconsistently supports relations between red meat intake and risks of cardiometabolic diseases such as cardiovascular disease and type 2 diabetes mellitus. Red meat is often not clearly or consistently defined within nutrition and health research and is consumed within healthy and unhealthy dietary patterns. These issues contribute to the conflicting findings. Observational data, which assess red meat (both unprocessed and processed) within an unrestricted Western-style dietary pattern, typically support positive associations with cardiometabolic disease incidence and mortality outcomes. Whereas experimental randomized controlled trial data consistently show that consuming healthy dietary patterns with or without the inclusion of lean unprocessed red meat, improve cardiometabolic disease risk factors. These discordant findings have left laymen, researchers,and policymakers alike to question whether a high intake of red meat is causally related to cardiometabolic disease outcomes. The results of the single blinded crossover randomized controlled feeding trial (Study 1, Chapter 3) support that consuming a U.S.-style healthy dietary pattern that included two 3oz servings/day of lean unprocessed beef did not adversely affect cardiometabolic disease risk factors. Based on observational and experimental research, the umbrella systematic review described in Chapter4, led to the inference that red and processed meats are not causally related with cardiovascular disease. However, relations between processed meat and mixed unprocessed and processed meat and type 2 diabetes were inferred to be potentially causal. Overall, the results described in this dissertation support that lean and unprocessed red meats consumed within healthy dietary patterns do not adversely affect cardiometabolic health