Abstract
Vegetarianism continues to increase globally due, in part, to perceived health benefits. Results from observational studies indicate that vegetarian dietary patterns are associated with favorable cardiometabolic risk factor profiles and lower risks of chronic diseases including obesity, diabetes mellitus type 2, cardiovascular disease, and cancer. Aside from avoidance of meat and the compensatory dietary alterations, vegetarians tend to practice lifestyle habits conducive to better health. Well-controlled intervention trials show minimal or no effects of lean meat intake on traditional markers for chronic disease risk, although biologically plausible mechanisms exist through which consumption of meat and other animal products could influence risks of cardiovascular disease and some cancers. Thus, at present, the degree to which favorable health outcomes associated with vegetarian diet patterns are attributable to avoidance of animal products per se is unclear. This issue has major public health implications because more than 95% of the US population are regular consumers of meat and other animal products. This review aims to summarize the evidence regarding vegetarian diet patterns and major chronic diseases, explore possible explanations for these relationships, and identify research gaps and opportunities to better define the health effects of vegetarian dietary patterns.