Cochrane corner: does the Mediterranean-style diet help in the prevention of cardiovascular disease?

There has been a longstanding interest in assessing the role of nutrition in human health. Diet is not merely the sum or combination of individual micronutrients and macronutrients. Indeed, the ancient Greek word ‘diaita’ means ‘way of living’, not just dietary needs, thus referring to the whole spectrum of life conditions: work, sleep, social environment and interactions, as well as daily activities. Over the last several decades, there has been increasing attention to investigate the potential benefits of whole dietary patterns in chronic disease prevention and management. Originating from Southern Europe, the traditional Mediterranean diet represents one of the most popular dietary patterns, with scientific investigations starting in the 1960s with the landmark Seven Countries study1 showing that populations in countries of the Mediterranean region, such as Greece and Italy, experienced lower cardiovascular mortality compared with northern European populations or the US population, likely as a result of different lifestyles including eating habits. Subsequently, a large body of observational data and meta-analyses of longitudinal prospective studies around the world have corroborated potential cardiometabolic benefits of the Mediterranean-style diet, with reduced rates of cardiovascular disease (CVD) and diabetes with increasing adherence to this dietary pattern. Experimental evidence also suggests potential mechanisms to explain the beneficial effect of the Mediterranean diet on cardiometabolic health. Key components of a Mediterranean dietary pattern are a high monounsaturated/saturated fat ratio (use of olive oil as main cooking ingredient and/or consumption of other traditional foods high in monounsaturated fats such as tree nuts) and a high intake of plant-based foods, including fruits, vegetables and legumes.2 Despite the consistent observational data, the trial evidence on the effectiveness of a Mediterranean-style diet in the prevention and management of major CVD is relatively limited or of questionable quality. This is a critical issue, as several scientific organisations …