Good Calories, Bad Calories

explanation.

For the Natal Indians, working primarily in and around sugar plantations, Campbell considered sugar the obvious suspect for their diabetes. He reported that the per-capita consumption of sugar in India was around twelve pounds yearly, compared with nearly eighty pounds for these working-class Natal Indians. The fat content of the diet in Natal was also very low, which seemed to rule out fat as the culpable nutrient. Excessive calorie consumption couldn’t be to blame, according to Campbell, because some of these impoverished Natal Indians were living on as little as sixteen hundred calories a day—“a figure in many countries which would be regarded almost as a starvation wage”—and yet they “were enormously fat and suffered from undoubted diabetes proven by blood tests.”

Campbell also found the disparities in diabetes prevalence and sugar consumption between urban and rural Zulus to be telling. The urban Zulu population, as hospital records demonstrated, was beset by diabetes. But in “thousands” of physical examinations performed on rural Zulus, Campbell wrote, “no case of diabetes has ever been discovered in any of them.” Studies of a rural Zulu population in 1953 and an urban population in Durban in 1957, wrote Campbell, concluded that the former were eating six pounds of sugar a year each, compared with more than eighty pounds for the latter. The fat content of the diet in both populations was very low—less than 20 percent of the total calories—which again seemed to rule out fat as the culpable nutrient. By 1963, according to the South African Cane Growers Association, the urban Zulus were eating almost ninety pounds of sugar per person annually, while the rural Zulus were eating forty pounds each (a sixfold increase in a decade).

“In the last few years sugar intake has risen drastically in Natal,” wrote Campbell, “because of very efficient advertising and because sugar has obviously reached as high an addictive status in our non-White people as in the Whites…. All [sugar]cane workers get a weekly ration of 1? lb. Andit is estimated that they can augment this by chewing sugar cane to the extent of ?–1 lb. daily!”

These sugarcane cutters, in whom, as Campbell noted, “diabetes is virtually absent,” turned out to be pivotal, in that later generations of diabetologists would cite them as compelling evidence that diabetes was not caused by eating sugar. Campbell, however, believed it was the refining of the sugar, which allowed for its quick consumption and metabolism, that did the damage; chewing sugarcane resulted in a slow intake of sugar that he believed would be relatively benign. Moreover, cane cutters would cut and move by hand as much as seven tons of sugarcane each day, which required an extraordinary effort that suggested to Campbell—as it had to Frederick Allen a half-century before—that a physically active lifestyle might ward off the danger of excessive sugar consumption, perhaps by burning the sugar as fuel to maintain the necessary “huge output of energy” before it could do its damage. “There are few occupations in the world,” Campbell wrote, “which entail such hard physical exertion as that involved in the cutting, moving, and stacking of sugar cane.”

Campbell also believed that diabetes required time to manifest itself. The cane cutters had been receiving their refined-sugar ration for only a decade at most. From his medical histories of the diabetic Zulus at his clinic, Campbell found what he called a “remarkably constant period in years of exposure to town life” before rural Zulus who had moved permanently into Durban developed diabetes. “The peak ‘incubation period’ in 80 such diabetics,” he wrote, “lay between 18 and 22 years.” Thus, Campbell suggested that diabetes would appear in a population to any extent only after roughly two decades of excessive sugar consumption, just as lung cancer from cigarettes appears on average after two decades of smoking. He also suggested that, if international statistics were any indication, the kind of diabetes epidemic they were experiencing among Natal Indians—or, for that matter, most Westernized nations—required a consumption of sugar greater than seventy pounds per person each year.

Campbell appears to be the first diabetologist to propose seriously an incubation period for diabetes. Joslin’s textbooks suggest he believed that if sugar consumption caused diabetes the damage could be done quickly—in a single night of “acute excess.” In arguing against the sugar theory of diabetes, Joslin said that no one to his knowledge had ever developed the disease after drinking the sugar solution used in a type of diabetes test known as a glucose-tolerance test.^*32 By the same logic, you could imagine that smoking a pack of cigarettes in an evening might cause lung cancer within the next few weeks in the rare unfortunate first-time smoker. That it has not been known to happen does not imply that tobacco is not a potent carcinogen.

In the early 1960s, Campbell began corresponding with a retired physician of the British Royal Navy, Surgeon Captain Thomas Latimore “Peter” Cleave. In 1966, they published Diabetes, Coronary Thrombosis and the Saccharine Disease, a book in which they argued that all the common chronic diseases of Western societies—including heart disease, obesity, diabetes, peptic ulcers, and appendicitis—constituted the manifestations of a single, primary disorder that could be called “refined-carbohydrate disease.” Because sugar was the primary carbohydrate involved, and the starch in white flour and rice is converted into blood sugar in the body, they opted for the name saccharine disease (“saccharine,” in this instance, meant “related to sugar” and rhymes with “wine,” in their usage, not “win,” as the artificial sweetener does).

After the book was published, Campbell returned to working exclusively on diabetes. Cleave tried to convince the medical establishment of the strength of evidence linking chronic diseases to the refining of carbohydrates, with little success. One biostatistician who insisted the idea should be taken seriously was Sir Richard Doll, director of the Statistical Research Unit of Britain’s Medical Research Council, who wrote the introduction to Diabetes, Coronary Thrombosis and the Saccharine Disease. In the early 1950s, Doll had published the seminal studies linking cigarettes to lung cancer. Doll later said of Cleave’s research, “His ideas deserved a lot more attention than they got.”

The primary obstacle to the acceptance of Cleave’s work was that he was an outsider, with no recognizable pedigree. He had spent his entire career with the British Royal Navy, retiring in 1962, after spending the last decade directing medical research at the Institute of Naval Medicine. Much of Cleave’s early career was spent in British naval hospitals in Singapore, Malta, and elsewhere, which gave him firsthand experience of how chronic-disease incidence could differ between nations.

Cleave’s nutritional education was furthered by the experience of his brother, Surgeon Captain H. L. Cleave, who spent the war years imprisoned by the Japanese in Hong Kong and then Tokyo. In the Hong Kong prison, peptic ulcers were a plague. The diets in these camps were predominantly white rice. Until vitamin-B supplements were distributed, beriberi was also a problem. After two years, many of the prisoners, including Cleave’s brother, were transferred to a camp outside Tokyo, where the ulcers vanished. In the Tokyo POW camps, the rice was brown, lightly milled, with unmilled barley and millet added.

In the decades after the war, Cleave became an obsessive letter-writer, corresponding with hundreds of physicians around the world, requesting information on disease rates and the occurrence and appearance of specific diseases. His 1962 book on peptic ulcers contained page after page of testimony from physicians reporting the relative absence of ulcers in those populations where sugar, white flour, and white rice were hard to come by.

Cleave’s intuition was to reduce the problem of nutrition and chronic disease to its most elementary form. If the primary change in traditional diets with Westernization was the addition of sugar, flour, and white rice, and this in turn occurred shortly before the appearance of chronic disease, then the most likely explanation was that those processed, refined carbohydrates were the cause of the disease. Maybe if these carbohydrates were added to any diet, no matter how replete with the essential protein, vitamins, minerals, and fatty acids, it would lead to chronic diseases of civilization. This would explain why the same diseases appeared after Westernization in cultures that lived almost exclusively on animal products—the Inuit, the Masai, and Samburu nomads, Australian Aborigines, or Native Americans of the Great Plains—as well as in primarily agrarian cultures like the Hunza in the Himalayas or the Kikuyu in Kenya.