The Scottish nutritionist Robert McCarrison was perhaps the leading proponent of the hypothesis that the chronic illnesses of civilization could be attributed to “the extensive use of vitamin-poor white flour and to the inordinate use of vitamin-less sugar.” McCarrison had founded a laboratory in India that would later become the National Institute of Nutrition and had spent nine years working in the Himalayas, “amongst isolated races far removed from the refinements of civilization,” as he explained in a 1921 lecture at the University of Pittsburgh. “During the period of my association with these peoples,” he wrote, “I never saw a case of asthenic dyspepsia, of gastric or duodenal ulcer, of appendicitis, of mucous colitis, or of cancer, although my operating list averaged over 400 operations a year.” McCarrison attributed their good health to several factors, including a diet of “the unsophisticated foods of Nature.” “I don’t suppose that…as much sugar is imported into their country in a year as is used in a moderately sized hotel of this city in a single day,” he said.

McCarrison’s research included a comparative study of the diets and physiques of the disparate populations and religious groups on the Indian subcontinent. The “physique of northern races of India,” McCarrison wrote, “is strikingly superior to that of the southern, eastern, and western races.” Once again, he attributed the difference to the vitamins and nutrients present in the northern-Indian diet but not elsewhere. They ate well-balanced diets, with milk, butter, vegetables, fruit, and meat—and ate their wheat ground course as wholemeal flour, which “preserves all the nutrients with which Nature has endowed it.” “White flour, when used as the staple article of diet,” wrote McCarrison, “places its users on the same level as the rice-eaters of the south and east of India. They are faced with the same problem; they start to build up their dietaries with a staple of relatively low nutritive value.” He also fed rats and mice in his laboratory on diets of these different populations and reported that the rats fared best on those diets containing “in abundance every element and complex for normal nutrition” and fared worst on those “excessively rich in carbohydrates, and deficient in suitable protein, mineral salts and vitamins.”