Ancel Keys was alert to the idea that sugar might be an alternative dietary explanation to his own as a cause of heart disease. From the late 1950s to the early 1970s, he held an ongoing debate in the scientific literature with John Yudkin, a professor of physiology at Queen Elizabeth College, London University, who at the time was the man behind the sugar hypothesis. "Keys was very opposed to the sugar idea," Daan Kromhout recalled in an interview, though he could not say why. Philosophers of science would say that the job of a scientist is to be as skeptical as possible about his or her own ideas, but Keys was evidently just the opposite. "He was so convinced that fatty acids were the thing in relation ot atheroschlerosis, he saw everything from that perspective," says Kromhout. "He was a very driven person and had his own point of view." About the views of others, Keys could be aggressively disaparing: Yudkin's idea that sugar causes heart disease is a "mountain of nonsense," he concluded at the end of a nine-page criticque in Artherosclerosis. "Yudkin and his commercial backers were not deterred by the facts; they continue to sing the same discredited tune," he wrote later.

Keys specifically defended his Seven Countries study from the idea that sugar might explain some of the mortality differences he observed. 

​

Nina Teicholz - TBFS - page 42