Diet and Fat: A Severe Case of Mistaken Consensus

In 1988, surgeon general C. Everett Koop made a statement that changed the course of American’s diets for many years to come. He said that high-fat foods were causing coronary heart disease and other deadly problems in Americans, and these high-fat foods were just as dangerous to public health as cigarettes.

Koop said, in the report detailing his fat findings, “The depth of the science base underlying its findings is even more impressive than that for tobacco and health in 1964.”

As it turned out, Koop’s statement was wrong.

What led a respected surgeon general to make such a mistake? According to this New York Times article, it was a case of an “informational cascade.”

A cascade of information can easily lead to the wrong conclusion.

It works like this: Someone has a bit of wrong information, but they are confident about it so they spout it out. A second person who is unsure decides that the first person must be right, and chooses to go along with their theory. A third person who may have had a right answer, then changes his mind because he believes the two others must know more than him.

And on it goes as each person assumes the others can’t be wrong.

Who was the first person to start the cascade of misinformation about fatty foods? It was Ancel Keys, a diet researcher for whom military K-rations are named.

He believed that dietary fat was causing heart disease in Americans back in the 1950s, and he soon got others to jump on the bandwagon.

Even the American Heart Association, which concluded in 1957 that “the evidence that dietary fat correlates with heart disease does not stand up to critical examination,” changed its position in 1960.

Why? Because Keys was on the committee issuing a new report that a low-fat diet was advised for people at risk of heart disease.

Since then, the “fat is bad” theory continued to be accepted as nutritional wisdom, even though clinical trials found no connection.


  • The New York Times October 9, 2007
    Dr. Mercola's Comments:
    It is amazing, but not surprising, how quickly one person’s flawed opinion can turn into the nutritional mantra of an entire country.

    As a result of nutritionists buying into Ancel Keys' "lipid hypothesis” that dietary fat causes heart disease, Americans were soon encouraged to substitute vegetable-based fats for animal fats, and to avoid red meat completely.

    What you may not know is that when Keys published his analysis that claimed to prove the link between dietary fats and coronary heart disease, he selectively analyzed information from only six countries to prove his correlation, rather than comparing all the data available at the time -- from 22 countries.

    As a result of this "cherry-picked" data, government health organizations began bombarding the public with advice that has contributed to the diabetes and obesity epidemics going on today: eat a low-fat diet.

    Of course, as Americans cut out nutritious animal fats from their diets, they were left hungry. So they began eating more processed grains, more vegetable oils, and more high-fructose corn syrup, all of which are nutritional disasters.

    I do believe that many of you are beginning to realize the flawed thinking behind the “fat is bad” mentality. The Atkins Diet helped open many to the idea that fat is OK to eat, and readers of my newsletter have known all along that healthy fats are essential for your health. In 2002, The New York Times also ran Gary Taubes’ What If It's All Been a Big Fat Lie?, which cast further doubt on this flawed “truth.”

    This new New York Times article is a poignant reminder of how important it is to NOT get caught up in what everybody else is saying, and to instead think for yourself.

    Today, many of you have switched over to the nutrition plan I recommend in Take Control of Your Health. And I’ve received countless testimonials to the improved health that results when you eat right for your nutritional type, and include plenty of the right fats in your diet.

    Many of you still write in to say that even your doctors are surprised by your results, so clearly there is still a lot of education to be done, but the key is that YOU are listening to your body, not the flawed theory of a 1950s nutritional researcher.
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