Ancel Keys, the Mediterranean Diet, and the Seven Countries Study: A Review

The identification of the "Mediterranean Diet" (MD) by Prof. Ancel Keys is described here, alongside its confirmation through the epidemiological study known as "The Seven Countries Study of Cardiovascular Diseases" (SCS). Prof. Keys' intuition on the possible dietary determinants of coronary heart disease (CHD) was derived from several pilot studies conducted in various countries. His impression was that the healthy diet was eaten along the Mediterranean shores of Italy, former Yugoslavia, and Greece, characterized by a large intake of bread, cereals, vegetables, fruit, and olive oil, with a small intake of meat, milk, dairy, and sugar products. The SCS was conducted across 16 cohorts of middle-aged men in seven countries (USA, Finland, the Netherlands, Italy, former Yugoslavia, Greece, and Japan), with assessments of usual eating habits, repeated medical examinations, and long-term follow-up. Analyses by Keys on the data from the first 15 years of follow-up indicated that low intake of saturated fatty acids (SAFA), usually derived from animal foods, was associated with the lower occurrence of and mortality from CHD, confirming the idea that a diet such as the Mediterranean Diet could be healthy. Further analyses by collaborators of the SCS, over a longer follow-up period, included the use of food groups and dietary scores of different types, confirming that cohorts with a Mediterranean Diet had a lower risk and death rate from CHD, whereas the reverse occurred in populations consuming an unhealthy diet.