Ancel Keys was a scientist who influenced the whole world for a whole generation about cholesterol and fat. And he was wrong.
As a influential and highly respected subject matter expert on weight and health in the 1950s, Ancel Keys hypothesized that the saturated fats in eggs and meat highly affects the amount and type of cholesterol (lipids)in the body. These raised levels of cholesterol lead inexorably to higher incidence of heart attacks and strokes. On top of that, these fats make you fat. Or, stated another way, Eggs = death.
If I hadn’t been in the egg industry, I might have never heard of Ancel Keys. Learning about him though has left me fascinated. Maybe there is something titillating in the mid-century, technocratic arrogance in the assertion of his will. Perhaps there is a moral to be learned about the traps of consensus and the folly of human wisdom. There are certainly aspects of the Ancel Keys’ story that resonate in the work Kahneman and Tversky on the way the human mind processes information. And, in the interest of self-awareness, I must admit that he had the role of a kind of evil adversary, denigrating and negating some of my favorite foods. Thanks to him, for 40 years or longer, eggs and meat were dietary pariah, a dangerous or unhealthy foods.
There is now a broader appreciation and understanding of the role of fats in the diet and fats and cholesterol in the body. Generally speaking, certain types of fats, ‘good fats,’ are now better recognized as having a healthy role. Additionally, the understanding of the mechanics of the body in transforming dietary fat to cholesterol has been radically revised and the previous models which cast the saturated fat as a contributor to higher levels of dangerous low density lipo-proteins (LDL) have been thrown out. And yet it remains so entrenched that most people still believe the simple proposition that consuming fats is invariably bad for you and many dietary guidelines still tell you to avoid fats indiscriminately.
How did we get there? Ancel Keys. If he looks like the mad scientist in a horror film, well, he had tendencies. He did military research during WWI to see how long a person could go without eating and the minimum calories soldiers could function on. Out of that research came the K ration, named after him and the bane of a generation of soldiers.
Keys believed that there was a relationship between fat consumption, hypercholesterolemia (increased serum cholesterol) and CVD (coronary vascular disease). This was based on some very preliminary studies from the 1920s so after the Korean War he undertook what became known as the Seven Countries study.
Keys conducted a lengthy study of diet, lifestyle and heart disease in the populations of industrialized countries. Keys showed that in seven countries, the US included, there was a correlation between a high consumption of dietary fat and CVD. Compellingly, the data seemed to demonstrate that as nations become wealthier and began to consume more meat and eggs, heart disease and strokes increased.
His theory came to be known as the lipid hypothesis and became very widely accepted in the medical and nutrition disciplines after the mid-1960s. Health officials in the government accepted the theory and in trying to improve public health, developed policies and education that moved people away from fats. Beef, pork and poultry became increasingly lean and cuts of meat were change to avoid fat. This was harder for eggs. Because of this and the many uses of eggs as an ingredient, the public was directed to minimize or avoid eggs altogether.
The first food pyramid came out of this consensus and, in order to make for the lost calories from protein sources, there was much more emphasis put on carbohydrates in the form of grains and cereals. By the 1980s, the food pyramid recommended the consumption up to 12 servings of grains a day. You can see why people started to be shaped like grazing animals
Much of this was enacted without further confirmation; major studies undertaken to confirm the theory were inconclusive and to some extent contradictory. But the lack of confirmation didn’t matter because the lipid hypothesis showed some very promising initial results. During the 60s and 70s, incidence in heart attacks and strokes in the US did drop and fairly significantly. It leveled off thereafter but cemented the consensus. The only large scale study using a low fat diet to show success (reduction of CVD) involved the use of statins (drugs like Lipitor) so the promotion of the lipid hypothesis became attractive to drug companies producing statins.
Yet, as people moved away from fat, the incidence of obesity and diabetes exploded. Most experts attribute this to the over consumption of carbohydrates. There is some doubt that, in the absence of drugs like statins and the trend away from smoking, the overall incidence of heart attacks and strokes would have changed all that much. In fact, the initial success of the reduction of CVD in the US is also strongly correlated with the policies, education and prohibitions against smoking.
So how did it go so wrong? Ancel Keys lied. Well, he fudged data, which is pretty much the same as lying. He left off the countries, 15 out 22, that contradicted his theory. It turns out there was a relatively weak correlation between high fat diets and CVD. A better correlative was wealth which led to more sedentary lifestyles and, at least during the 50s, more smoking (watch Mad Men). But Ancel, like the mad scientist in the movie when his experiment goes horribly wrong, stuck to his theory and never fessed up to the cooking the books.
Part of the problem was the nature of consensus. Given acceptance of a theory that holds together well, even one based on bad data, it’s hard to change people’s minds, let alone whole industries. Research shows that when people have a strongly held conviction, data that makes contradicts their view point actually makes them stronger in their opinion and to reject the data and/or the source of the new information. A lot of the data refuting the Keys research has been out there for a while; it just took a lot of time to break down resistance.
Part of the problem was that there were many interests benefiting from the consensus: Doctors and scientists who were advocates of the high carb, low fat diets, pharmaceutical companies promoting statins, agribusiness, the USDA and any number of authors and experts who staked their reputations on the promotion of the lipid hypothesis.
But ultimately it comes down science: the scientific method will ultimately improve our knowledge but the process is by nature deliberate. It just took a while, and improvements in technology, to get to the point where enough experts could stand up with data and say ‘No, the consensus is wrong.’ Now we know better. But I wonder how much this episode contributed to today’s skepticism regarding medical expertise.
If you enjoyed this little story, please stay tuned. He will shortly have a discussion Jim Painter, PhD in nutrition who will shed even more light on these topics.
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