Seven Countries Study

The Seven Countries Study is the world's first multi-country epidemiological study. It examines the relationships between lifestyle, diet, coronary heart disease (CHD) and stroke in different populations from different regions of the world. The study was conceived by physiologist Ancel Keys in the 1950s.

The main hypothesis was that the rate of coronary disease in populations and individuals would vary in relation to their physical characteristics and lifestyle, particularly in fat composition of the diet and serum cholesterol levels.

​The countries are Finland, Greece, Italy, Japan, Netherlands, USA and former Yugoslavia. The study enrolled all men aged 40 to 59 years in 16 cohorts in those countries.

One of the conclusions from the study is that "the average saturated fat intake, average serum cholesterol level and 10-year CHD mortality rates in the 16 cohorts were strongly correlated."
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This conclusion is in strong contrast to the result in Zutphen, which was the cohort chosen in the Netherlands for the study.  The conclusion from Zutphen is that "saturated fat intake of individuals was not related to either serum cholesterol or CHD mortality."

The study also concludes that "large differences in absolute CHD risk were observed among the cohorts, with high absolute risks in northern Europe and the United States and low absolute risks in Mediterranean southern Europe and Japan."

And: "The similar relative risks and different absolute risks of CHD among the cohorts implies that at the same serum cholesterol level in high-risk cultures, elevated serum cholesterol levels need to be treated more intensely than in low-risk cultures to achieve target levels and potential prevention."

Criticism
​Some problems with The Seven Countries Study are:

• ​The study is based on the Lipid Hypothesis.
• The study did not enroll any women.
• The study disregarded the observations from Zutphen, which contradicted the Lipid Hypothesis.​

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References
 - Seven countries study: Official website.
​ - Wikipedia: Seven countries study.
​ - Raymond Reiser: "Saturated fat in the diet and serum cholesterol concentration: A critical examination of the literature"
​ - People.com: Dr. George Mann says low cholesterol diets are useless, but the "Heart Mafia" disagrees.
 - Tom Naughton: "Science for smart people".
​ - Dr. John Yudkin: "Diet and coronary thrombosis hypothesis and fact."