Good Calories, Bad Calories

In the late 1970s, the World Health Organization launched a research project known as MONICA, for “MONItoring CArdiovascular disease,” that was similar in concept to Keys’s Seven Countries Study but considerably larger. The study tracked heart disease and risk factors in thirty-eight populations in twenty-one countries—a total population of roughly six million people, which unlike previous studies included both men and women. Hugh Tunstall-Pedoe, the MONICA spokesman, has described the project as “far and away the biggest international collaborative study of cardiovascular disease ever carried out” and noted that, “whatever the results, nobody else has better data.” By the late 1990s, MONICA had recorded 150,000 heart attacks and analyzed 180,000 risk-factor records. Its conclusion: heart-disease mortality was declining worldwide, but that decline was independent of cholesterol levels, blood pressure, or even smoking habits.

The MONICA investigators suggested reasons why their study might not have confirmed Keys’s hypothesis, among them the possibility, as Tunstall-Pedoe noted, that with populations “the contribution of classical risk factors is swamped by that of other dietary, behavioral, environmental, or developmental factors.” He also discussed something that may have contributed initially to the widespread belief in Keys’s hypothesis: the tendency to publish or pay attention to only that evidence that confirms the existing beliefs about heart disease and risk factors. “If you do a study in your population and you show a perfect correlation between risk factors and heart disease, you rush off and publish it. If you don’t, unless you have great confidence in yourself, you worry that perhaps you didn’t measure something properly, or perhaps you’d better keep quiet, or perhaps there’s something you haven’t thought about. And by doing this, there is a risk of myths’ becoming self-perpetuating.” “There are people,” Tunstall-Pedoe said, “who want to believe that if we find anything less than 100-percent correlation between traditional risk factors and trends in heart disease, we are somehow traitors to the cause of public health, and what we say should be suppressed, and we should be ashamed of ourselves. Whereas we are asking a perfectly reasonable question, and we came up with results. That is what science is about.”

In the two decades since the NIH, the surgeon general, and the National Academy of Sciences first declared that all Americans should consume low-fat diets, the research has also failed to support the most critical aspect of this recommendation: that such diets will lead to a longer and healthier life. On the contrary, it has consistently indicated that these diets may cause more harm than good. In 1986, the year before the National Cholesterol Education Program recommended cholesterol-lowering for every American with cholesterol over 200 mg/dl, the University of Minnesota epidemiologist David Jacobs visited Japan, where he learned that Japanese physicians were advising patients to raise their cholesterol, because low cholesterol levels were linked to hemorrhagic stroke. At the time, Japanese men were dying from stroke almost as frequently as American men were succumbing to heart disease. Jacobs looked for this inverse relationship between stroke and cholesterol in the MRFIT data and found it there, too. And the relationship transcended stroke: men with very low cholesterol seemed prone to premature death; below 160 mg/dl, the lower the cholesterol, the shorter the life.

In April 1987, the Framingham investigators provided more reason to worry when they finally published an analysis of the relationship between cholesterol and all mortality. After thirty years of observation, there was a significant association between high cholesterol and premature death for men under fifty. But for those over fifty, both men and women, life expectancy showed no association with cholesterol. This suggested, in turn, that if low cholesterol did prevent heart disease, then it must raise the risk of dying from other causes.

This was compounded by what may have been the single most striking result in the history of the cholesterol controversy, although it passed without comment by the authorities: those Framingham residents whose cholesterol declined over the first fourteen years of observation were more likely to die prematurely than those whose cholesterol remained the same or increased. They died of cardiovascular disease more frequently as well. The Framingham investigators rejected the possibility that the drop in cholesterol itself was diet-related—the result of individuals’ following AHA recommendations and eating low-fat diets. Instead, they described it as a “spontaneous fall,” and insisted that it must be caused by other diseases that eventually led to death, but they offered no evidence to support that claim.