Estruch R et al. (2006) Effects of a Mediterranean-style diet on cardiovascular risk factors: a randomized trial. Ann Intern Med 145: 1–11

Accumulating evidence suggests that adherence to a Mediterranean-style diet, a diet low in saturated fat and high in monounsaturated fat and dietary fiber, reduces the risk of cardiovascular disease. To examine the short-term effects of Mediterranean dietary habits on intermediate markers of cardiovascular risk, a multicenter trial was carried out in Spain.

The investigators allocated 772 adults, at high risk of cardiovascular disease, to either a low-fat diet or one of two Mediterranean-style diets. Those assigned to a Mediterranean-style diet were given either 1l of virgin olive oil per week or 30g of nuts per day. Both Mediterranean diet groups received personalized dietary advice, while those allocated to the low-fat diet were given a leaflet listing dietary recommendations. Changes in cardiovascular risk markers from baseline levels were examined at a 3-month follow-up visit.

Compared with participants in the low-fat diet group, those following a Mediterranean-style diet showed a decrease in systolic blood pressure, lower fasting blood glucose levels, and a reduction in the plasma concentration of several inflammatory biomarkers at follow-up. Those in the Mediterranean diet groups had an improved lipid profile after 3 months; lipid profile did not change in the low-fat diet group. The nut-supplemented Mediterranean diet had a triglyceride-lowering effect. Nondiabetic individuals following the Mediterranean-style diets recorded lower fasting insulin levels and reduced insulin resistance compared with similar participants in the low-fat diet group.

The authors suggest that the cardiovascular benefits of Mediterranean dietary habits might be related to changes in lipid profiles, and to reductions in blood pressure, inflammatory status and insulin resistance.