The degree to which starch is refined in diets, particularly when the intake of starch is high, may itself be an important factor in cancer risk, as may the volume of refined starches and sugars in diets. Epidemiological studies have not, however, generally distinguished between degrees of refining or processing of starches, and there are, as yet, no reliable epidemiological data specifically on the effects of refining on cancer risk.

Cleave’s saccharine-disease hypothesis may be intuitively appealing, but it is effectively impossible to test without a randomized controlled trial. If Cleave was right, then epidemiologists comparing populations or individuals with and without chronic disease have to take into account not just sugar consumption but flour, and whether that flour is white or whole-grain, and whether rice is polished or unpolished, white or brown, and even how much beer is consumed compared with, say, red wine or hard liquor. They might have to distinguish between table sugar and the sugar in soft drinks and fruit juices. Just as fats are now divided into saturated, monounsaturated, and polyunsaturated (and, ideally, into the various subcategories, including stearic acid and oleic acid), carbohydrates have to be separated into subcategories as well. It would be easy, Cleave suggested, to gather together the twenty fattest people in any neighborhood and find that “they wouldn’t have a sweet tooth among them, and they wouldn’t like sugar”—they would all be beer drinkers. “Beer is full of malt sugar and enormously fattening,” he said.

It may have been these complications that led indirectly to a pared-down version of Cleave’s hypothesis—one that would receive far more publicity—blaming coronary heart disease, diabetes, and other chronic diseases effectively on sugar alone. So said John Yudkin, who, unlike Cleave, was a prominent figure in the nutrition-research community. In 1953, he had founded the department of nutrition at Queen Elizabeth College in London, the first dedicated department of nutrition in Europe. In the late 1950s, Yudkin began advocating a very low-carbohydrate diet for weight loss and wrote a popular diet book, This Slimming Business. He believed starches and sugars brought nothing of nutritional importance to the diet except calories—sugar was the worst offender—and so they were the obvious nutrient to remove from a weight-loss diet.