Retrospective #3: Ancel Keys and the Lipid Hypothesis

Ancel Keys, a prominent University of Minnesota physiologist who was keenly interested in diet and nutrition, was attending a medical conference in Rome in 1951 where he learned that “heart disease was rare in some Mediterranean populations who consumed a lower fat diet.” He noted, too, that “the Japanese had low fat diets and low rates of heart disease. He hypothesized from these observations that fat was the cause of heart disease.”¹ These observations and associations about dietary fat have since come to be known as the Lipid Hypothesis.

Just two years later, Keys, now convinced that dietary fat was the cause of heart disease, published his “Six Country Analysis” (1953), an epidemiological study. Years later, with his hypothesis now firmly entrenched, he published an updated version (Harvard University Press, 1980) as the “Seven Countries Study.” In this study Keys points out an association between dietary fat and mortality from heart disease. Critics pointed out then, and with increasing traction today, that Keys had data for 22 countries, but selected data from just 6 (later 7). As an example, Keys excluded France, a country with a high fat diet and low rates of heart disease. His detractors then and now claim that Keys had selected only data to support his hypothesis, and that that was bad science. Further, his was a retrospective analysis, not a prospective study, and thus did not prove causality. This distinction is an important and fundamental precept of scientific investigation, but one that is often overlooked by the media and lay public.

Meanwhile, the American Heart Association (AHA), founded in 1924 by cardiologists, had “re-invented” itself in 1948 as a fundraising organization. In 1956 their TV fundraiser on all three networks (that was all there was at the time) urged Americans to reduce their intake of total fat, saturated fat, and cholesterol. Then, when President Eisenhower had his first heart attack in 1958, the AHA recommended Americans eat “heart-healthy” margarine, corn oil, breakfast cereals and skim milk, a diet that the President (and millions of us) unhappily complied with.

Today, most “health-conscious” Americans still largely follow this diet, perhaps with the exception of margarine, which was basically a partially hydrogenated vegetable oil made with trans fats. We are now told, and I certainly agree, that trans fats are really bad for us.  But, we still (many of us) largely avoid eggs, butter, marbled beef and other fatty cuts of meat, and high-cholesterol-containing foods like liver and shrimp (and eggs, butter and cream!).

Meanwhile, by 1961 Ancel Keys was on the Board of the AHA, the AHA had adopted Keys’s low-fat diet, and Ancel Keys made the cover of Time Magazine under the banner “Diet and Health.” Fat became public health enemy #1.

That same year the famous Framingham Heart Study, another epidemiological study of 5209 people begun in 1949, noted that men under 50 with elevated serum (blood) cholesterol were at greater risk of heart disease. However, these men were also more likely to smoke, be overweight, not exercise, and, although not noted, have high blood sugar. These first three observations became the famous “risk factors” that, to this day, are the mantra of the the public health establishment, the medical community, and the media who trumpet it. Little noted was the finding that for men over 50 there was no association between elevated serum cholesterol and heart disease.

There were, of course, opposing voices in the medical community, including senior researchers at Rockefeller and Yale and the U. of Pennsylvania. They and others pointed out that elevated triglycerides (and low HDL) were associated with increased risk of heart disease and that low-fat, high-carbohydrate diets caused elevated triglycerides, but their findings were disregarded and their voices ignored. By 1972 the federal government’s WIC program only allowed skim or low-fat milk for kids over age 2. The die was cast. We had started down the road of government Dictocrats intervening in what we eat. Still more ominous interventions were to come. Stay tuned.

¹ The Timeline History of Heart Disease in this and succeeding columns draws heavily from a piece by the same title published by Diet Heart Publishing  at http://dietheartpublishing.com.