The absence of malignant cancer in isolated populations prompted questions about why cancer did develop elsewhere. One early hypothesis was that meat-eating was the problem, and that primitive populations were protected from cancer by eating mostly vegetarian diets. But this failed to explain why malignancies were prevalent among Hindus in India—“to whom the fleshpot is an abomination”—and rare to absent in the Inuit, Masai, and other decidedly carnivorous populations. (This hypothesis “hardly holds good in regard to the [American] Indians,” as Isaac Levin wrote in 1910. “They consume a great deal of food [rich in nitrogen—i.e., meat], frequently to excess.”)

By the late 1920s, the meat-eating hypothesis had given way to the notion that it was overnutrition in general, in conjunction with modern processed foods, lacking the vital elements necessary for health, that were to blame. These were those foods, as Hoffman put it, “demanding conservation or refrigeration, artificial preservation and coloring, or processing otherwise to an astonishing degree.” As a result of these modern processed foods, noted Hoffman, “far-reaching changes in bodily functioning and metabolism are introduced which, extending over many years, are the causes or conditions predisposing to the development of malignant new growths, and in part at least explain the observed increase in the cancer death rate of practically all civilized and highly urbanized countries.”

White flour and sugar were singled out as particularly noxious, because these had been increasing dramatically in Western diets during the latter half of the nineteenth century, coincident with the reported increase in cancer mortality. (They would also be implicated in the growing incidence of diabetes, as we’ll discuss, and appendicitis.) Moreover, arguments over the nutritive value and appeal of white flour and sugar had been raging since the early nineteenth century.

Flour is made by separating the outer layers of the grain, containing the fiber—the indigestible carbohydrates—and virtually all of the vitamins and protein, from the starch, which is composed of long chains of glucose molecules. White sugar is made by removing the juice containing sucrose from the surrounding cells and husk of the cane plant or sugar beet. In both cases, the more the refining, the whiter the product, and the lower the vitamin, mineral, protein, and fiber content. The same is true for white rice, which goes through a similar refining process.

This might seem obviously disadvantageous, but white flour had its proponents. It was traditionally considered “more attractive to the eye,” as Sir Stanley Davidson and Reginald Passmore observed in their textbook Human Nutrition and Dietetics (1963). It was preferred by bakers for its baking properties, and because it contains less fat than wholemeal flour it is less likely to go rancid and is more easily preserved. Millers preferred it because the leftover bran from refining rice and wheat (as with the molasses left over from refining sugar) could be sold profitably for livestock feed and industrial uses. Nutritionists also argued that white flour had better “digestibility” than whole-meal, because the presence of fiber in the latter prevented the complete digestion of any protein or carbohydrates that were attached. White flour’s low protein, vitamin, and mineral content also made it “less liable than whole meal flour to infestation by beetles and the depredation of rodents,” as Davidson and Passmore wrote.