At my Quantified Self talk I described data that suggested butter improved my mental function. During the question period, a cardiologist in the audience said something about me killing myself — butter is unhealthy. The usual view.
I said I thought the evidence for the usual view was weak. He said, “The Framingham studies.” That was epidemiology, I said. It is notoriously hard to understand. My data was from something like an experiment. Much easier to understand. (And the Framingham study is a terrible example of the supposed evidence. To quote from it: “In the period between the taking of the diet interviews and the end of the 16-year follow-up, 47 cases of de novo CHD developed in the Diet Study group. The means for all the diet variables measured were practically the same for these cases as for the original cohort at risk.”) He replied that the reduction in heart disease in recent years was more support for the usual view. I said the recent decline in heart disease could have many explanations other than a reduction in animal fat intake. Many things have changed over the last 20 years.
There is epidemiological evidence that saturated fat is bad, yes, but it is not the Framingham study nor the recent decline in heart disease. And it really is difficult to interpret. The butter-is-bad interpretation could easily be wrong. The obvious problem is that, after people are told butter is bad, people who try hard to be healthy avoid butter. And they do a lot of other things, too, to be healthy. So butter consumption ends up confounded with a dozen other variables believed to affect your health. When I was growing up, my parents avoided butter because margarine was much cheaper. So butter consumption is confounded with income, another problem.
My tiny experiment, whatever its problems, was much easier to interpret.