In the United States, however, Keys’s hypothesis ruled. Keys himself went after Yudkin in a letter that he first distributed widely to investigators in 1970, before it was published in the journal Atherosclerosis. Keys called Yudkin’s arguments for the role of sugar in heart disease “tendentious” and his evidence “flimsy indeed” he treated Yudkin as a figure of ridicule. What made Keys’s critique so ironic, though, is that virtually every argument that he invoked to criticize Yudkin’s hypothesis had been used in the past as criticism of his own. Most were equally valid for both, and spoke to the flaws in the epidemiologic evidence—the use of international cause-of-death statistics and food-consumption data or dietary-recall surveys to draw conclusions about cause and effect—rather than to the actual validity of the hypotheses. Keys’s case against Yudkin eventually came to rest almost entirely on his invocation of the Seven Countries Study as support for his hypothesis. In fact, the Seven Countries Study had been one of the very few studies that had measured sugar consumption in its populations, and sugar indeed turned out to predict heart-disease rates as well as saturated fat did.

By the early 1970s, Keys’s dietary-fat hypothesis of heart disease, despite the ambiguity of the evidence, was already being taught in textbooks and in medical schools as most likely true. After Yudkin retired in 1971, his hypothesis effectively retired with him. His university replaced him with Stewart Truswell, a South African nutritionist who was among the earliest to insist publicly that Keys’s fat theory of heart disease was assuredly correct and that it was time to move on to modifying the diets of the public at large accordingly. Truswell believed it was more important for the prevention of heart disease to convince the public to eat more onions, for their reported ability to alter the “tendency to thrombosis,” than to eat less sugar.

Yudkin spent his first year of retirement writing a book on his sugar theory, published in 1972 and entitled Pure, White and Deadly in England and Sweet and Dangerous in the American edition. It did not serve to move the medical-research community closer to embracing either Yudkin or his theory. By the late 1970s, to study the potentially deleterious effects of sugar in the diet, says Sheldon Reiser—who did just that at the U.S. Department of Agriculture’s Carbohydrate Nutrition Laboratory in Beltsville, Maryland—and to talk about it publicly, was to endanger your reputation. “Yudkin was so discredited,” says Reiser; “he was ridiculed in a way. And anybody else who said something bad about sucrose, they’d say, ‘He’s just like Yudkin.’”

Chapter 7

Chapter Seven

FIBER

The thing is, it’s very dangerous to have a fixed idea. A person with a fixed idea will always find some way of convincing himself in the end that he is right.

ATLE SELBERG, winner of the 1950
Fields Medal in Mathematics