The Mediterranean Diet - II
The study that indicates that indeed the Mediterranean diet does have a protective effect was published in Lancet, v 360, p1455 (2002). In this study, 1000 patients who had angina pectoris, myocardial infarction or other coronary artery disease risk factors, were randomly assigned to one of two diets. Half of them were assigned to a diet rich in fruit, vegetables, whole grains, walnuts and almonds ("intervention diet"); the other half were assigned to the National Cholesterol Education Program "prudent diet".
The patients on the intervention diet had their total cholesterol to HDL ratio decrease from 4.9 to 4.2. We recall from another section that this ratio correlates with a reduced CHD risk. In fact, the intervention diet reduces the total nuber of cardiac events by 0.51 (0.31 to 0.71 Margin of Error), compared to the "prudent diet". We might conclude that "prudent diet" is less prudent than the intervention diet!
Another direct measurement of the effect of a Mediterranean diet was determined in a study published in Circulation (v 99, p 779, 1999) that assigned one of two diets at random to patients who had a first heart attack (myocardial infarction). One diet was a Mediterranean-style diet, and the other - a "prudent" western-style diet. The study finds that the Mediterranean diet results in a risk reduction of 0.53 (Margin of Error between 0.38 to 0.74), even though the cholesterol levels and blood pressure are almost identical between the two groups.
A very recent reference (New England Journal of Medicine, Feb 25 2013) lends even more credence to the large effect of the Mediterranean diet. They measured heart attacks, stroke or death from cardiovascular causes. Three diets were tested: 1) A Mediterranean diet with supplemented extra-virgin olive oil, 2) the Mediterranean diet supplemented with mixed nuts, and 3) a control diet, where the only intervention was advice to reduce fat consumption. Diets 1) and 2) resulted in a risk reduction of 30%, similar the the risk reduction that can be achieved with statins! The margin of error is still large - 4% to 48% in the 95% confidence level margin. However, this is one more study that adds to the growing volume of evidence in favor of the Mediterranean diet.