The enduring curse of Ancel Keys
Who is Ancel Keys? If you ever wondered why we think eggs and shell fish are harmful, why low-fat foods sell so well, why we have become a society obsessed with cholesterol levels, why statins are among the most profitable drugs peddled by our pharmaceutical companies, you just have to look at the work of Ancel Keys. In 1953, after examining data on dietary intake in 22 countries, he published the Seven Countries Study that linked high fat/high cholesterol diets to increased coronary artery disease (CAD). The fact that he eliminated 15 countries from his final paper (countries in which his thesis may well have been contradicted), that his dietary information was imprecise, and that his use of relative risk exaggerated the impact of fat intake on heart disease are not even the most distressing problems with his work. More salient, his study, as is true of all of the studies that link high cholesterol levels and high fat diets to CAD (including the Framingham Heart Study and MRFIT), did not comment on whether low fat diets and reduced cholesterol levels help people live longer and better. The fact is, when all of these studies have been reexamined, the answer is NO. People do not live longer or better when they eat low fat diets and have low cholesterol levels. Often they substitute fat with carbohydrates. Often they neglect to eat “good” fats. And virtually always their cholesterol level is not related to how much fat/cholesterol they eat, is not predictive of their CAD risk, and certainly does not correlate to quality or length of life. In fact, a recent study examining thousands of people presenting to the hospital with heart attacks found that as many had low cholesterol as high cholesterol. Cholesterol and fat intake seems to make no significant impact on health. Cholesterol levels seem to have no correlation to health outcomes. Cardiologists and scientists can break down cholesterol into as many components as they can measure, and it still does not predict who will have heart disease. And yet we continue measuring and fixing cholesterol levels, as we continue to preach the wisdom of low fat diets. Why?
For years, drug companies have devised chemicals to lower cholesterol levels. All were successful in their primary mission: cholesterol levels did drop. But, despite early studies using relative risk and faulty design to prove otherwise, none of the studies actually showed a decrease in CAD or death rate. Most of the drugs had significant side effects, and few are used today. Then came statins, and it seemed we found the wonder drug. Studies showed even more dramatic relative risk drops in the risk of heart attack and CAD death in people who took statins; the always unpublished absolute benefits were far more modest, and the impact on overall death rate were even more negligible. It seemed that the benefit was most prominent in people with pre-existing heart disease, and that the benefit had nothing to do with a person’s cholesterol level. Yes, cholesterol had nothing to do with the positive impact of statins! People with low and high cholesterol improved equally, demonstrating conclusively that the benefit of statins are related to something other than cholesterol, likey their anti-inflammatory impact on blood vessels. Now some clinical guidelines suggest statin use only for people with pre-existing vascular disease or those at high risk without any regard to the cholesterol level. These guidelines do not even suggest measuring cholesterol since it is an irrelevant marker of disease. Statins are not without risk. They destroy muscle, and in the elderly this can lead to weakness and falls. They interfere with several important enzymes in our body, the impact of which is unknown. Their long term effects may be far better or worse than we know. To many elderly patients of mine, even those with heart disease, their minimal benefit is clearly overshadowed by their many possible adverse effects. But trying telling a patient or his cardiologist that. They don’t buy it. They continue to measure cholesterol, and they insist that we must use statins to improve the number. Such an approach, despite the science that disputes its wisdom, is the current standard of care.
We are a cholesterol obsessed society. Medicare’s quality indicators implore us to measure and treat cholesterol in a variety of conditions. My patients incessantly request that I check cholesterol levels. Everyone seems to want to be on a statin, to keep measuring levels, and to make sure those levels are “fixed.” And low fat diets are still a fad with loyal followers. Many of my patients still think eggs are bad for them. The truth is, they are very healthy, and the yolk may be the best part. Sadly, Ancel Keys planted a seed that does not seem to want to go away. Cholesterol is yet another number that has reached a feverish pitch in our collective minds, despite its insignficance. It can be measured and it can be fixed. But by doing that, we well be doing much more harm than good. Thank you very much Ancel Keys!