Ancel Keys

Ancel Benjamin Keys (January 26, 1904 – November 20, 2004) was an American scientist who studied the influence of diet on health. In particular, he hypothesised that different kinds of dietary fat had different effects on health.

He examined the epidemiology of cardiovascular disease (CVD) and was responsible for two famous diets: K-rations formulated as balanced meals for combat soldiers in World War II and the Mediterranean diet, which, with his wife Margaret, he popularized. Science, diet, and health were central themes in his professional and private lives.

Early life

Keys attended the University of California, Berkeley, where he received a B.A. in economics and political science (1925), an M.S. in biology (1929), and is a '30 University of California, San Diego Alumus receiving a Ph.D. in oceanography and biology from the Scripps Institution of Oceanography. He earned a second Ph.D. in physiology at Cambridge in 1938. In 1936, he became a professor at the University of Minnesota, where he established the Laboratory of Physiological Hygiene. Keys directed the laboratory from 1939 until his retirement in 1975. After that he moved to Pioppi, a small village of fishermen in southern Italy where he lived until 2003 studying food habits of the locals, leading to the foundation of health evidence for the Mediterranean Diet.

Professional

During World War II, Keys studied starvation and sustenance diets using 32 conscientious objectors from Civilian Public Service as test subjects in the Minnesota Starvation Experiment, and eventually producing his two-volume Biology of Human Starvation (1950). His interest in diet and CVD was prompted, in part, by seemingly counterintuitive data: American business executives, presumably among the best-fed persons, had high rates of heart disease, while in post-war Europe, CVD rates had decreased sharply in the wake of reduced food supplies. Keys postulated a correlation between cholesterol levels and CVD and initiated a study of Minnesota businessmen (the first prospective study of CVD), culminating in what came to be known as the Seven Countries Study. These studies found strong associations between the CVD rate of a population and average serum cholesterol and per capita intake of saturated fatty acids. Then, as now, critics have rightfully pointed out that this "strong association" becomes weaker when data from other countries are added to the mix and there have been allegations that Keys "cherry picked" the data to support his hypothesis.

From the early 1950s, Keys actively promoted his findings to an increasingly health-conscious public. The resulting "cholesterol controversy" revealed sharp divisions in post-war scientific culture over whether the statisticians' "strong associations" could provide scientific certainty. In its simplest form, the debate over cholesterol, dietary saturated fat and CVD pitted "interventionists" against those calling for further studies—preferably clinical or laboratory studies. The role of cholesterol in CVD was confirmed in the 1990s, when huge studies with powerful cholesterol-lowering drugs showed definitively that lowering LDL cholesterol indeed reduced the risk of cardiovascular disease. (Law MR, Wald NJ, Rudnicka AR. Quantifying effect of statins on low density lipoprotein cholesterol, ischaemic heart disease, and stroke: systematic review and meta-analysis. BMJ. 2003 Jun 28;326(7404):1423. www.bmj.com/cgi/content/full/326/7404/1423). The significance of dietary saturated fat intake for cholesterol and CVD remains an area of heated debate.

However, already in the 1960s Keys was able to convince a sizable part of the US public that replacing saturated by unsaturated fat would reduce blood cholesterol and the incidence of coronary heart disease. The resulting changes in the composition of food fats led to a doubling of the proportion of the unsaturated fatty acid, linoleic acid, in the body fat of Americans between 1960 and 1975 (Katan MB, Beynen AC. Linoleic acid consumption and coronary heart disease in U.S.A. and U.K. Lancet. 1981 Aug 15;2(8242):371). Rates of coronary heart disease in the US began to fall from 1968 onwards, and about half of the decline was ascribed to changes in lifestyle including diet (Goldman L, Cook EF. The decline in ischemic heart disease mortality rates. An analysis of the comparative effects of medical interventions and changes in lifestyle. Ann Intern Med. 1984 Dec;101(6):825-36).

Keys had concluded that saturated fats as found in milk and meat have adverse effects opposite to the beneficial effects of the unsaturated fats found in vegetable oils. These same unsaturated fats and oils are however, found in meats and to a larger extent than Dr. Keys ever gave these foods credit for in any of his work. This message was obscured for a 20-year period starting around 1985, when all dietary fats were considered unhealthy. This was driven largely by the hypothesis that all dietary fats cause obesity and cancer (Prentice RL, Sheppard L. Dietary fat and cancer: consistency of the epidemiologic data, and disease prevention that may follow from a practical reduction in fat consumption. Cancer Causes Control. 1990 Jul;1(1):81-97). The tide turned in the late 1990s because the link between fat and cancer could not be substantiated, and because low-fat diets were found to be ineffective against the obesity epidemic which was engulfing the US in spite of reductions fat intake (Katan MB, Grundy SM, Willett WC. Should a low-fat, high-carbohydrate diet be recommended for everyone? Beyond low-fat diets. N Engl J Med. 1997 Aug 21;337(8):563-6; discussion 566-7).

With the advent of ever-more powerful cholesterol lowering drugs, high cholesterol has ceased to be a major cause of premature heart disease in affluent countries. Its place has been taken by obesity and the subsequent type 2 diabetes, problems for which the diets developed by Keys offer no solution, though he appreciated the connection between obesity and cardiovascular disease (Circulation 1952:5; 115-118).

Keys also popularized the use of the body mass index (BMI) as a measure of body fat, following a 1972 paper.

Keys was always considered an interventionist. He generally shunned food fads and vigorously promoted the benefits of the "reasonably low-fat diets," he contrasted with "the North American habit for making the stomach the garbage disposal unit for a long list of harmful foods."[1] Keys' studies and recommendations have had a substantial impact on changes in the U.S. diet that may have caused a downward trend in CVD.[2]. Several recent studies have vindicated Keys' thesis that unsaturated oils are more effective at improving markers of CVD than high-carbohydrate low-fat foods. Because of his influence in dietary science, Keys was featured on the cover of the January 13, 1961 issue of Time magazine.

Ancel Keys died on November 20, 2004, two months before his 101st birthday. A year earlier, he had left Pioppi, his beloved village in Italy where he had spent 28 years of his life.

Criticism

Ancel Keys was criticised by Uffe Ravnskov amongst others for falsifying his conclusions by selecting data. Ravnskov examined the data that Keys used and found no correlation to back up Keys findings. He concluded that Keys had deliberately excluded from his dataset any countries which did not support his hypothesis.

Gary Taubes criticised Keys for the same reason in his book "Good Calories, Bad Calories".

References

•  This article incorporates public domain material from Morbidity and Mortality Weekly Report. Centers for Disease Control and Prevention.

External links

• Blackburn, Henry. "Ancel Keys". University of Minnesota. Retrieved 2007-04-15.