Recently, a number of writers identifying themselves as "health-science journalists" have been calling on Americans to "end the war on fat" as they promote a high-fat, low-carbohydrate diet ("Chocolate milk in the schools and other products of expert opinion," June 22). What's puzzling is that they draw attention to their arguments by using personal attacks on one of Minnesota's premier scientists, Ancel Keys.

Keys was a University of Minnesota physiologist who spent most of his career conducting wide-ranging studies on the relationship of lifestyle — especially the foods we eat — to heart disease. He worked at the university from the late 1930s until his death at age 100 in 2004, and he carried out classic experiments of diet effects on blood-cholesterol levels in the laboratory and of diet associations with heart attacks among cultures with contrasting traditional eating patterns. "Contrasting" is the operative word here.

Keys' most influential work is the Seven Countries Study. Begun in 1958 and still in progress, it compares diet, risk factors, and rates of heart attack and stroke among regions of Greece, Italy, the former Yugoslavia, the Netherlands, Finland, the United States and Japan. Some recent (nonscientist) interpreters of the study have accused Keys of "cherry-picking" the countries with "preconceived" ideas about what he would find. Demonstrating a lack of understanding of how scientists approach new questions, they suggest he should have chosen specific other countries or should have chosen his sites "randomly." Any savvy scientist at an early phase of questioning knows to look first not randomly but across wide variations of the cause under consideration, in this case diet.

Keys chose the study areas because of their apparent differences in traditional diet, between the extremes of the rice- and vegetable-based diets of Japanese farmers and fishermen and the fatty meat, cheese and butter lunches of Finnish loggers. Another criterion was the availability of collaborators who understood the cultures and could provide logistical support and access to communities.

After years of observations among these regions, Keys and colleagues found major, five- to tenfold differences in heart-attack rates in relation to diet, an association compatible with the hypothesis that diet influences heart-attack risk and one congruent with their findings in feeding experiments back home. They also showed that the lowest heart-attack rates and longest survival occurred in both Japan, with its low-fat diet, and Greece, where the diet was relatively high in fat, mostly from olive oil. Their common factor was not the amount of fat people ate but the type of fat, with both areas consuming very little saturated fat.

The critics also accuse Keys of suppressing evidence collected during the studies in Crete. They claim that he rejected the results of hundreds of individual diet questionnaires and that his characterization of the diet was inaccurate because it was based on a survey that took place during Lent. Both charges are false and misleading.

Keys determined early that occasional questionnaires about foods we eat were unreliable, useful only for detecting significant departures from a population's typical eating habits. Although individual questionnaires were recorded, the study did not rely on them for the regional comparisons. Instead, Keys collected actual foods eaten for a full week among randomly selected families and chemically analyzed their nutrient content in the standardized laboratory in Minnesota. Repeat food collections were scheduled in different seasons during different years to provide a valid estimate of the nutrients consumed by an entire population. Events such as religious holidays and crop failures have an effect on what people eat at a given time and are part of the bigger picture of a community's eating pattern. Avoiding variations in eating at different parts of the yearly cycle would have been the real "cherry-picking."

The eating pattern that came out of these international comparisons is being referred to by critics as "low-fat" or "extreme low-fat," even though it includes leaner meats and lower-fat dairy foods as well as many types of vegetable oils. In fact, only Keys' saturated-fat recommendation — less than 10 percent of calories — might be considered "low." In the popular cookbooks written with his wife, Margaret, Keys called the pattern "eating well" and, later, "eating well the Mediterranean way."

In the most bizarre accusation of all, several writers are laying the blame on Keys for our modern epidemics of obesity and diabetes. It all started in the 1950s, they say, with Keys' undue influence on the American Heart Association and the later U.S. government dietary guidelines. The idea that one person could hold such sway for years over these notoriously skeptical bodies strains credulity. It was the strength of the evidence, plus a pragmatic decision how best to reduce saturated-fat consumption, not Keys' "force of will," that inspired the dietary policies.

In the meantime, social and cultural changes already underway truly did set the nation on the path to obesity. Restaurants increased portion sizes and people consumed more calories. Suburbs were built without sidewalks, and schools installed pop machines and served fast food. The food industry, already expert at marketing high-fat packaged foods, saw a new marketing opportunity and developed companion product lines in which fats were replaced by sugar and other simple carbohydrates or substitutes — something Keys never advised nor supported. Industry and advertisers, not Keys, led shoppers to believe that these "reduced-fat" foods were the healthier choices.

In addition to finding — and exploiting for profit — a common villain in Keys, these writers use a number of devices to promote what Nina Teicholz, author of "The Big Fat Surprise," advocates as a return to "tallow and lard." Innuendo, distortions and accusations may be good for media attention and book sales, but they can do real damage — not only to the reputation of a pioneering researcher, but to public understanding of the scientific method and the evolving science of nutrition. It's time to end the war on Ancel Keys.

Dr. Henry Blackburn is a professor emeritus and researcher in the Division of Epidemiology and Community Health in the School of Public Health at the University of Minnesota. He succeeded Ancel Keys as director of the Laboratory of Physiological Hygiene and was the project officer of the Seven Countries Study in its early years.