Ancel Keys did not manipulate his data

Popular commentators frequently accuse Keys of manipulating data in his 1953 paper, Atherosclerosis, A Problem in Newer Public Health. ¹

This study is popularly referred as the “Six-Countries Study”. A number of popular commentators think this is the Seven Countries Study — they count England and Wales as two countries.

This paper was presented in Amsterdam in 1952 and in January 1953 in New York.

On page 4 of this paper, Keys lists 16 countries (which includes France, The Netherlands, Switzerland, and Sweden) and compared their all-cause death rates to the United States. United States compared unfavourably to all countries and Keys believed that what was possible for other countries “should be possible for Americans.” The mortality data was for the years 1947– 1949.

The only countries that have a higher all-cause mortality rate for males are South Africa for 50-54 years old and Portugal for 40-44 year old which have mortality rates of 102% and 139% of the US mortality rate respectively. The increase in Portugal’s mortality rate is attributed to tuberculosis and violence.

On page 17 of this 22-page paper, Keys graphed the mortality rate for degenerative heart disease and fat intake for six countries that he stated had “fully comparable dietary and vital statistics data.” The food data was obtained from FAO for the year 1949.

This graph causes a great deal of consternation in the popular press. The claim is made that Keys “cherry-picked” his data, which is stating that he was dishonest.

The entire paper needs to be viewed as a whole – not one page of a minor discussion paper. This paper was meant to be a starting point for determining why the cardiovascular diseases mortality rate were much worse in the USA than other 16 countries listed.

Yerushalmy and Hilleboe criticized this paper in the publication Fat in the Diet and Mortality from Heart Disease, ² claiming that Keys only choose 6 countries (Japan, Italy, England & Wales, Australia, Canada, U.S.) that supported his hypothesis instead of using the World Health Organization data from the 22 countries that was available. The data for the 22 countries that Yerushalmy and Hilleboe listed were for the years 1951-1953, a period which is after the publication of Keys’s paper.

Keys states:

At the time of Keys’s paper, (1953), the categories for heart disease were:

B-26 category was further divided into 3 sub-categories.

Yerushalmy and Hilleboe examined the following categories to determine if they were more appropriate.

Yerushalmy and Hilleboe did NOT examine B-26 (420) and B-26 (422) which Keys utilised and which they hypothesised was the most appropriate.

The calories used was calculated from the national food balance data by the F.A.O. (1949).

The death rates were from official sources for each country that had comparable statistical data. Keys states why he excluded data from some counties.

Even if data from all the 22 countries are included, it still shows:

This observation is clearly stated in Yerushalmy and Hilleboe’s paper. Yerushalmy and Hilleboe were criticising the methodology and the classifications and sub-classifications of heart disease that were used. They were not criticising the lack of correlation.

Using the data supplied by Yerushalmy and Hilleboe for all of the 22 countries, it shows the following Pearson’s correlation coefficients with category B-26 of heart disease. Yerushalmy and Hilleboe used rank correlations – not linear correlations.

As a generalization, 90% indicates a very strong correlation, 70-90% a strong correlation and 50-70% a moderate correlation. The claim that there is no correlation (even with all the countries included) is simply false.

Taubes, Teicholz and other popular commentators ignore the fact that Yerushalmy and Hilleboe found the greatest correlation with the percentage of animal protein and heart disease. Once again, that is simply being dishonest. (Note the difference is insignificant – and saturated fat and animal protein are often found in the same food.)

In the book The Big Fat Surprise: why butter, meat, and cheese belong in a healthy diet, Nina Teicholz claims that, ³

Keys was opposed to dietary guidelines. He advocated “our” version of the Mediterranean Diet that was based on the diets of Greece, southern Italy and the Mediterranean regions of Spain and France in the 1960s.

Below are extracts from Teicholz’s book as she tries to justify her argument that Keys manipulated his results. The data that Teicholz has added is shown in red text. It is clear that it is from a completely different set of data to that supplied by Keys. Teicholz has added data for Great Britain for the years 1951-1953 whilst Keys used data for England and Wales for the year 1949 supplied by the Food and Agriculture Organization of the United Nations. The 22 countries that is frequently cited comes from Yerushalmy and Hilleboe.

Henry Blackburn, Keys’s long-time colleague in Minnesota singles out Teicholz for a special mention.

If you go back to the original Food and Agriculture Organization document for the year 1949, you will discover that there were actually 36 countries available. Perhaps we should be asking why Yerushalmy and Hilleboe only included 22 countries. No – not really, it is irrelevant.

Teicholz has changed the date in the heading from Males aged 50-59, 1951-1953 to 1950 so it fits with her chronology of Keys’s deception. That can be only described as being dishonest. Clearly this data was not available to Keys as he first presented his talk in Amsterdam in 1952.

The graph shows an exponential correlation between the death rate and fat calories as a % of total calories. The coefficient of determination (R^2) is 0.48, which is a moderate correlation. Other dietary components show a greater correlation.

The Six-Countries Study was a minor discussion paper that was ignored until Gary Taubes discovered it to criticise Keys in the book, Good Calories, Bad Calories in 2007. ⁷

In 1951, Keys was working at Oxford when the Food and Agriculture Organization asked him to chair their first conference on nutrition in Rome. Keys states, “The conferees talked only about nutritional deficiencies”. When he asked about the new epidemic of coronary heart disease, Gino Bergami, Professor of Physiology at the University of Naples, said “coronary heart disease was no problem in Naples”.

In 1952, Keys and his wife Margaret visited Naples. Margaret measured serum cholesterol concentrations and found them to be very low except among members of the Rotary Club. Heart attacks were rare except amongst the rich whose diet included daily servings of meat. He obtained similar results in studies in Madrid.

Keys and his wife Margaret wrote three books extolling the virtues of the Mediterranean diet: Eat Well and Stay Well (1959), The Benevolent Bean (1967); and How to eat well and stay well the Mediterranean Way (1975). ^{8 9 10}

Popular commentators frequently confuse the “Six-Countries Study” with the Seven Countries Study.

Below are two commentaries by self-styled health experts.

Both are completely confused.

Ede states that the Seven Countries Study was published in 1970 but claims that when Yerushalmy and Hilleboe examined the data that they found no correlation between fat and heart disease. Yerushalmy and Hilleboe found correlation with “% fat in diet and heart disease“, “% saturated fat in diet and heart disease mortality” and an even greater correlation with “% animal protein in diet and heart disease mortality“.

Yerushalmy and Hilleboe’s paper was published in 1957. The data that Yerushalmy and Hilleboe refers to was not available until 1956 – a long time after Keys published his “minor discussion paper” in 1952 and 1953.

The “Internationally Recognized Wellness Expert” makes similar nonsensical claims, being confused with dates and the studies that he has “examined in detail“.

Dr. Henry Blackburn is a professor emeritus and researcher in the Division of Epidemiology and Community Health in the School of Public Health at the University of Minnesota. He succeeded Ancel Keys as director of the Laboratory of Physiological Hygiene and was the project officer of the Seven Countries Study in its early years.

He wrote the following on the 18th Jul 2014 in the Minesotta Star Tribnue.

In the most bizarre accusation of all, several writers are laying the blame on Keys for our modern epidemics of obesity and diabetes. It all started in the 1950s, they say, with Keys’ undue influence on the American Heart Association and the later U.S. government dietary guidelines. The idea that one person could hold such sway for years over these notoriously skeptical bodies strains credulity. It was the strength of the evidence, plus a pragmatic decision how best to reduce saturated-fat consumption, not Keys’ “force of will,” that inspired the dietary policies.

In the meantime, social and cultural changes already underway truly did set the nation on the path to obesity. Restaurants increased portion sizes and people consumed more calories. Suburbs were built without sidewalks, and schools installed pop machines and served fast food.

The food industry, already expert at marketing high-fat packaged foods, saw a new marketing opportunity and developed companion product lines in which fats were replaced by sugar and other simple carbohydrates or substitutes — something Keys never advised nor supported.

Industry and advertisers, not Keys, led shoppers to believe that these “reduced-fat” foods were the healthier choices.

In addition to finding — and exploiting for profit — a common villain in Keys, these writers use a number of devices to promote what Nina Teicholz, author of “The Big Fat Surprise,” advocates as a return to “tallow and lard.” Innuendo, distortions and accusations may be good for media attention and book sales, but they can do real damage — not only to the reputation of a pioneering researcher, but to public understanding of the scientific method and the evolving science of nutrition. It’s time to end the war on Ancel Key. ¹¹

A biography of Ancel and Margaret Keys, Genius and Partnership Ancel and Margaret Keys and the Discovery of The Mediterranean Diet has been written by Joseph Dixon. ¹²

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Last updated on Friday 12 June 2026 at 11:34 by administrators

1. Keys, A. (1953) Atherosclerosis: a problem in newer public health. Journal of Mt Sinai Hospital. July-Aug; 20 (2), 118–139.
2. Yerushalmy, J. & Hilleboe, H. E. (1957) Fat in the Diet and Mortality from Heart Disease. New York State Journal of Medicine. 57 (14), 2343–2354.
3. Teicholz, N. (2014) The Big Fat Surprise: why butter, meat, and cheese belong in a healthy diet – Revised. Revised Edition. Scribe.
4. Keys, Ancel, and Margaret Keys. 1975. How to Eat Well and Stay Well the Mediterranean Way. Doubleday, Garden City, NY. p4
5. Keys, Ancel. (1995) Mediterranean Diet and Public Health : Personal Reflections. American Journal of Clinical Nutrition 61 (6):1321S–1323S.
6. Blackburn, H. (2014) In defense of U research: The Ancel Keys legacy – Star Tribune (Accessed 2 February 2018).
7. Taubes, G. (2007) Good Calories, Bad Calories. New York: Random House.
8. Keys, A. & Keys, M. (1959) Eat Well and Stay Well. Doubleday, Garden City, NY.
9. Keys, A. & Keys, M. (1967) The Benevolent Bean. New York: Doubleday, Garden City, NY.
10. Keys, A. & Keys, M. (1975) How to eat well and stay well the Mediterranean way. Doubleday, Garden City, NY.
11. Blackburn, H. (2014) In defense of U research: The Ancel Keys legacy – Star Tribune [online]. Available from: http://www.startribune.com/in-defense-of-u-research-the-ancel-keys-legacy/267581481/ (Accessed 2 February 2018).
12. Dixon, J. L. (2015) Genius and Partnership Ancel and Margaret Keys and the Discovery of The Mediterranean Diet. New Brunswick, NJ: Joseph L. Dixon Publishing.