Five days after Kolata’s article on the negative results from the Phoenix and NCI trials, the Times published an explanatory article by Kolata—“Health Advice: A Matter of Cause, Effect and Confusion”—in which she discussed why the public had come to be misled on the benefits of fiber. She suggested that one reason was the loose use of language: “Scientists and the public alike use words like ‘prevents’ and ‘protects against’ and ‘lowers the risk of’ when they are discussing evidence that is suggestive, and hypothesis-generating, as well as when they are discussing evidence that is as firm as science can make it.” Burkitt’s fiber hypothesis, she said, had been based on hypothesis-generating data—international comparisons, in particular—and had then been refuted by the best studies science could do. “Yet even in the aftermath of the high-fiber diet studies,” Kolata noted, “researchers were speaking confidently about other measures people could take to ‘prevent’ colon cancer, like exercising and staying thin. And they were saying that there were reasons to keep eating fiber because it could ‘reduce the risk’ of heart disease. When asked about the evidence for these statements, the researchers confessed that it was, of course, the lower level hypothesis-generating kind.”

The very next day, the Times ran an article by Burros entitled “Plenty of Reasons to Say, ‘Please Pass the Fiber,’” in which she suggested, based on what Kolata would have called “hypothesis-generating data,” that eating fiber “significantly” lowers the risk of heart attack in women, and that “fiber is also useful in preventing the development of diabetes,” “helps control obesity,” and “may also be useful in reducing hypertension.” Less than a month later, Brody followed with an article entitled “Vindication for the Maligned Fiber Diet,” noting that, although fiber had “been knocked around a bit lately, after three disappointing studies failed to find that a high-fiber diet helped to prevent colon cancer,” a recent study published in the New England Journal of Medicine of thirteen subjects followed for six weeks suggested it helped them to better control their diabetes and so should be eaten on that basis. “Since diabetes greatly increases a person’s risk of developing heart disease and other disorders caused by fat-clogged arteries,” Brody wrote, “the results of this study are highly significant to the 14 million Americans with Type 2 diabetes.” By 2004, Brody was advocating high-fiber diets solely for their alleged ability, untested, to induce long-term weight loss and weight maintenance. In effect, fiber had now detached itself from its original hypothesis and existed in a realm always a step beyond what had been tested. Cleave’s hypothesis that refined carbohydrates and sugars were the problem, the single best explanation for the original data, had been forgotten entirely.

Chapter 8

Chapter Eight

THE SCIENCE OF THE CARBOHYDRATE HYPOTHESIS