Good Calories, Bad Calories

After returning to South Africa, Campbell went to work at the King Edward VIII Hospital, which served exclusively the “non-white” population, and admitted some sixty thousand patients a year while administering to six hundred thousand outpatients. Once again, says Campbell, he was struck by the “remarkable difference in the spectrum of disease,” in this instance between the urbanized Zulus, who were appearing with the same spectrum of diseases he had seen among the blacks of Philadelphia, and what he called their “country cousins” who still lived in rural areas. The Natal Indian population became the primary subject of Campbell’s research when he realized that four out of every five of his diabetic patients came from that impoverished Indian community.

The ancestors of these Natal Indians had arrived in South Africa in the latter half of the nineteenth century to work as indentured laborers on the local sugar plantations. When Campbell began studying them in the late 1950s, over 70 percent lived below the poverty line, and many still worked for the sugar industry. Campbell and other researchers carried out half a dozen health surveys of this Natal Indian population. The incidence of diabetes among middle-aged men in some of the villages ran as high as 33 percent. It was nearly 60 percent among the ward patients and outpatients at the King Edward VIII Hospital. In ten years of operation, Campbell’s clinic treated sixty-two hundred Indian diabetics, out of a local Indian population of only 250,000. A “veritable explosion of diabetes is taking place in these people,” Campbell wrote, “in whom the incidence of the disease is now almost certainly the highest in the world.” Campbell contrasted this with the numbers in India itself, where the average incidence of diabetes across the entire country was approximately 1 percent. This disparity between the incidence of diabetes in India and the incidence among the Indians of Natal ruled out a genetic predisposition to diabetes as a meaningful 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 1½ lb. Andit is estimated that they can augment this by chewing sugar cane to the extent of ½–1 lb. daily!”