Why are saturated fats healthy again? Why do the latest nutritional guidelines still have a very low cap on salt despite all the contradictory data?
There is a lot of confirmation bias in nutrition and those end-oriented beliefs make it easy to unconsciously mold results to match the numbers to the goal, like doing surveys about food recall and subtly quantifying the results one way or the other. Then it's off to publish a diet book or become an expert on the latest fad carcinogen.
Then there is the unsubtle kind of bias, like not publishing results that don't fit the narrative of claims that are currently popular, which would lead to no sitting on panels creating government nutrition guidelines. A recent instance of that was a BMJ paper about a study that was in defiance of the principal investigator's beliefs about saturated fats and whose inconvenient findings never saw the light of day.
So saturated fats are not a death sentence for a "healthy heart"? What's the big deal, everyone says that now, isn't that just more bandwagon following, like claims we're getting with pre-diabetes and other beliefs that have gotten the attention of the federal government and therefore grant funding?
It's distinct because these data were compiled from the Minnesota Coronary Experiment, which took place from 1968 to 1973, after the government had already said butter was a killer and margarine was good -- and the full results had not been published, even though the study was of almost 10,000 men and women from ages 20 to 97 and showed increased mortality rate for those on the “heart healthy” diet, in defiance of the 'saturated fats are bad, vegetables are good' mantra. The co-creator of this inconvenient data was Dr. Ancel Keys, the famed epidemiologist and proponent of the Mediterranean Diet (and Body Mass Index) who arguably did the most to promote saturated fat as the enemy of "heart health." It violated what he felt to be true and was getting funding from the U.S. Public Health Service and National Heart Institute to show to be true. So it disappeared until the raw data was rediscovered and analyzed by the team in BMJ, from 9-track magnetic tapes, grant proposals, FORTAN coding sheets and paper records.
How could that happen?
One of the greatest myths promoted by some government-funded researchers and activists looking for confirmation is that because their money has been washed by the federal government, the resulting work is more ethically pure than corporate scientists. Aside from failing a simple logic test -- does that mean a corporate scientist who goes to work for the government is suddenly ethically pure again? -- it fails to recognize the human condition: People are going to try and make the boss happy, and if the boss says saturated fats are bad and you have inconvenient data, it is better to stick those in the drawer. Sometimes the boss is your own belief system and the federal government, too.
As Professor Aaron Carroll notes in the New York Times, this was a large, randomized, controlled trial and if you are going to show one thing causes another, those are how you do it. Yet this never even got discussed at the highest levels despite it being federally funded and conducted by a national thought leader on heart disease. It lends weight to the idea that when it comes to nutrition, personal beliefs often trump science. It took decades for the flawed thinking about saturated fat to be overturned and meanwhile all we got obeying these guidelines was more obesity and now nutritionists are moving onto new things to claim will be a magic bullet, like sugar or wheat or whatever other diet book may get on the New York Times bestseller list.
It's not the first time, it may not be the last, but allowing this sort of thing to happen over and over has undermined public acceptance of science overall. No wonder it is easy for anti-science groups like Natural Resources Defense Council and Environmental Working Group to scare everyone about every chemical or food they target. No wonder politically partisan science bloggers insist "ties to industry" (except their own) are bad; they may choose never to see that there is plenty of bias in academia too, and they may also never see papers being suppressed because of inconvenient truth.
Yet we know that in real science those "wait, that can't be right" moments of discovery and diving deeper into finding out why are how great things are achieved. It is increasingly obvious that nutrition has become a world view rather than science. The CEO of the $4 billion CrossFit exercise video company actually argues that even if you burn calories to offset the ones you take in, from something like soda, you will still gain weight and get diabetes -- because it's soda and it apparently has some otherworldly, magical power. He is not just making that up, there are nutritionists who put that wacky stuff in his head.
Obviously this has a cascading effect through culture when it comes to science. Why believe climate scientists are not sticking contrary data in the drawer and blocking anyone who disagrees on global warming from committees, jobs or tenure when academics rationalize it in other fields?
In nutrition and epidemiological claims, a lot of what gets published is just picking a curve and then suggesting a cause. Want to get media attention? "Show" something is linked to cancer epidemiologically. Get a few of those same correlations from others in your circle into a meta-analysis and put the authors on an IARC panel and they will create a "weight of evidence" and then California will put a warning label on whatever new endocrine-disrupting carcinogen you found and then a bunch of bottom-feeding scholars will rush to affirm it with more epidemiology papers.
If none of that ever gets replicated in trials, that is going to get far less media attention. Meanwhile you will have spent your time worrying that eating sausage is just as dangerous as smoking cigarettes or inhaling asbestos, at least until never published data gets uncovered showing that was never true at all.