The Mediterranean diet and mortality--olive oil and beyond.

The concept of the Mediterranean diet originated from the Seven Countries Study initiated by Ancel Keys in the 1950s. The study showed that, despite a high fat intake, the population of the island of Crete in Greece had very low rates of coronary heart disease and certain types of cancer and had a long life expectancy. The traditional dietary patterns typical of Crete, much of the rest of Greece, and southern Italy in the early 1960s were considered to be largely responsible for the good health observed in these regions. 1 The main characteristics of the Mediterranean diet (see Figure) include an abundance of plant food (fruits, vegetables, whole-grain cereals, nuts, and legumes); olive oil as the principal source of fat; fish and poultry consumed in low-to-moderate amounts; relatively low consumption of red meat; and moderate consumption of wine, normally with meals. Over the years, the Mediterranean diet has been promoted as a model for healthy eating. The diet, however, has been surrounded by as much myth as scientific evidence. There is no single “Mediterranean diet.” More than 15 countries border the Mediterranean Sea, and their dietary habits, the types of food produced, and their cultures vary considerably. Moreover, the differences that Keys observed in mortality from coronary disease among different populations could well be attributable to confounding by other lifestyle-related factors, such as physical activity. The first clinical-trial evidence in support of the health benefits of the Mediterranean diet came from the Lyon Diet Heart Study, 2 in which 605 patients who had had a myocardial infarction were randomly assigned to a “Mediterranean-style” diet or a control diet resembling the American Heart Association Step I diet. Patients in the Mediterranean-style–diet group were encouraged to consume more fruits, vegetables, and fish; to eat less red meat; and to replace butter and cream with margarine rich in a -linolenic acid (to mimic the n¡3 content of the traditional Cretan diet). After a mean follow-up of 27 months, the rate of coronary events was reduced by 73 percent, and total mortality was reduced by 70 percent in the intervention group. More recently, Singh et al. 3 tested an “Indo-Mediterranean diet” in 1000 patients in India with existing coronary disease or at high risk for coronary disease. As compared with the control diet, the intervention diet — characterized by increased intake of mustard or soybean oil, nuts, vegetables, fruits, and whole grains — reduced the rate of fatal myocardial infarction by one third and the rate of sudden death from cardiac causes by two thirds. In this issue of the Journal, Trichopoulou et al. (pages 2599–2608) report the results of a population-based study involving 22,043 apparently