About Rationally Speaking
Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.
Tuesday, February 14, 2006
Low-fat diets and the nature of science
Of course, part of the beauty of science is that sometimes it contradicts “what everybody knows,” and it does so data in hand. One can bring up all the common wisdom and occasional anecdotes one wants, but eight years and 49,000 subjects is a lot of data to argue against. Or is it? Like any scientific study, the one published in JAMA has limitations. For one thing, it applies to women, and therefore says little or nothing about men's physiological reactions to the same diets. Second, the authors of the study looked at total fats, while the recent literature has argued that it is crucial to distinguish between unsaturated (good) and saturated (bad) fat, especially since it is the latter that causes increases in cholesterol, and presumably leads to related health problems such as heart disease.
Another point to understand in evaluating the results of the study is that even if (as it seems the case) a total low-fat diet does not prevent the diseases in question, it doesn't follow that a high (as in, humongous) fat diet will do no harm. The JAMA paper simply cannot be interpreted as a license to stop going to the gym and binge on fried chicken.
Fine, but what's the average educated reader of the New York Times to do with this information? Can't scientists figure things out once and for all and tell us what to do? Well, no, at least not most of the time. Mind you, at this point it is pretty much certain that the earth isn't the center of the universe, we can all count on that. But when it comes to complex problems, such as human physical and mental health, the best we can do is to read the latest findings, try to understand the inevitable limitations of the study, and mull over the possible implications for our personal choices. This is why science literacy is important in modern societies. This is why both scientists and journalists have an obligation to talk to the public and explain not just the specifics of a particular study, but the general nature of the scientific enterprise. Ignorance is not bliss, but poorly understood information can kill you almost as effectively.