Mediterranean diet
The Mediterranean diet is included among dietary patterns that may reduce the risk of cardiovascular diseases. A 2013 Cochrane review found limited evidence that a Mediterranean diet favorably affects cardiovascular risk factors. A 2013 meta-analysis compared Mediterranean, vegan, vegetarian, low-glycemic index, low-carbohydrate, high-fiber, and high-protein diets with control diets. The research concluded that Mediterranean, low-carbohydrate, low-glycemic index, and high-protein diets are effective in improving markers of risk for cardiovascular disease and diabetes, while there was limited evidence for an effect of vegetarian diets on glycemic control and lipid levels unrelated to weight loss. However, reviews of early 2016 have been more cautious: concerns were raised about the quality of previous systematic reviews examining the impact of a Mediterranean diet on cardiovascular risk factors, further standardized research has been found to be necessary, and the evidence for the possible prevention of vascular disease by the Mediterranean diet was "limited and highly variable". Reviews in 2016-17 reached similar conclusions about the ability of a Mediterranean diet to improve cardiovascular risk factors, such as lowering the risk for hypertension and other cardiovascular diseases.