“It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.”- Mark Twain
“No one can see a bubble. That’s what makes it a bubble.”– The Big Short
“I cannot give any scientist of any age any better advice than this: The intensity of the conviction that a hypothesis is true has no bearing on whether it is true or not.”- Peter Medawar
If the US government and other prominent health organizations endorse a particular measure, we assume it must be scientifically based and appropriately researched. After all, they can point to research and if that research wasn’t substantial then they wouldn’t endorse it, now would they? Unfortunately, that’s not how the public health world works sometimes.
Now while we’d love to live in a world where all public health recommendations are made solely on the basis of accurate research with the health of the population in mind, and where we could see unicorns at the local zoo, both are impossibilities. The fact is that research is conducted and analyzed by human beings who have their own agendas, desires, egos, and biases, all of which sometimes carry over into the research and into subsequent recommendations based on that research. Sometimes, this means that an idea that isn’t fully substantiated makes its way into health policy. So how does this type of thing happen? Well let’s take a look at our case study: the American Heart Association’s low fat diet.
Earlier in the 20th century, the average American diet consisted of very high fat foods with a great deal of animal protein and/or sugar and very little fruits and vegetables. In some areas- especially the South- food was the accepted indulgence of choice since alcohol was considered a sin. In the 1940’s and 1950’s, research began to show that high levels of cholesterol were correlated with heart disease and some researchers began proposing that overweight Americans should decrease their fat intake. In 1977, the McGovern report instructed that Americans in general should eat more whole grains, less meat, more fruits and vegetables and substitute nonfat dairy products for whole fat ones. From Anne LaBerge’s overview of the history of the low-fat diet:
“A turning point in obesity/heart disease studies came in 1983 with the publication of an article based on the Framingham studies, which cited obesity as an independent risk factor for heart disease.21 This finding lent further support to the low-fat approach because scientists believed that the low-fat diet might not only prevent coronary heart disease, but also could promote weight loss, thereby reducing the incidence of obesity. By 1984, the scientific consensus was that the low-fat diet was appropriate not only for high-risk patients, but also as a preventive measure for everyone except babies.22 Low fat carried the day, in spite of continued serious skepticism.23 The diet-heart hypothesis remained a hypothesis, but, as if already proven, it became enshrined in federal public health policy and was promoted by health-care practitioners and the popular health media. By 1988, the Surgeon General’s report emphasized the health dangers of dietary fat, and in 2000, the federal government’s “Report on Nutrition and Health” labeled fat the unhealthiest part of the American diet. From 1984 through the 1990s, dietary fat was increasingly blamed not only for coronary heart disease but also for overweight and obesity.”24
So here we have a hypothesis and some research on a high-risk population. And for people who were eating primarily meat, dairy and sugar, a diet that focused on whole grains and produce might actually bring about some positive changes. However, instead of doing further research to understand if this is actually a correct thing for every single man, woman and child, health authorities latched on to it and ran with it as if it was fact, promoting it for all. Doctors who were skeptical of the idea that the low fat diet was correct for every person accept infants were roundly criticized.
Harvard Medical School sums up the low fat diet this way: “Once the main strategy for losing weight, low-fat diets were shoved aside by the low-carb frenzy. But healthy fats can actually promote weight loss, and some fats are good for the heart; eliminating them from the diet can cause problems. Since fat contains nine calories per gram while carbohydrates contain four, you could theoretically eat more without taking in more calories by cutting back on fatty foods and eating more that are full of carbohydrates, especially water-rich fruits and vegetables. Still, such a diet tends to be less filling and flavorful than other diets, which lessens its long-term appeal. And if the carbs you eat in place of fat are highly processed and rapidly digested, you may be sabotaging your weight-loss plan.” Again, serious problems with the low fat diet as a long-term, blanket strategy for weight loss and health.
Despite emerging research on the importance of moderate consumption of healthy fats, we can still see the vestiges of the low-fat diet “gospel” in government supported food programs. Children at schools drink low fat or non fat milk. Women and children on WIC can only use their WIC vouchers to purchase whole dairy products under special permission- such as if the woman or child is severely underweight.
And this isn’t the first time an idea has quickly morphed from hypothesis to full blown public health campaign. Take Shaken Baby Syndrome– a diagnosis founded largely on research performed on adult baboons and confessions from people under severe emotional duress. Shaking a baby is still abusive and can seriously injure a baby, but the actual diagnosis of Shaken Baby Syndrome as the only cause of subdural hematoma in an infant has come into question in court cases and rightly so. Interestingly enough, we have a great deal of material on not shaking babies, but very little about other abusive behavior towards infant and children. Shaking is specifically singled out in these campaigns.
Or if we really want a throwback, how about the idea that circumcision of male infants should be routine because it would prevent masturbation and a proposed host of accompanying ills? Robert Darby’s paper on the subject notes the “insularity” of the American medical profession in clinging to a belief in “congenital phimosis” long after it had been debunked in Europe. Indeed, despite a mountain of evidence to the contrary, medical texts continued to promote circumcision as a preventative for masturbation into the 1970’s. Whatever your thoughts on circumcision, the point is that the reasons for its widespread promotion during the twentieth century were not scientifically grounded (but rather derived largely from social and cultural ideas) and were presented as fact long after scientific evidence had proved otherwise.
The list can go on and on of “sacred cows” that are founded largely on a belief that something is to true to be untrue or that we simply don’t want to believe it to be true. The mortgage market could never fall apart, it’s simply too safe. The NFL has a history of presenting flawed research as its proof that football players can not develop serious brain injuries from repeated head trauma. Enron was simply too safe and conservative an investment to fail. Madoff was too trustworthy to screw over the investment world.
Sure, you can go around waving research and credentials in people’s faces saying that it’s proof of what you want to hear. But that doesn’t mean the research was carried out in a systematic and unbiased manner or that its results are being correctly interpreted. Just think about next time someone tells you that the research on the safety and efficacy of vaccines is undeniable.