Why Nutrition Studies Suck
by Leo Brown New Food Culture
Itís easy to get scared or excited by dramatic headlines. Did you hear that high, or even slightly elevated, blood sugar has been linked to dementia?
When I read that, I got scared and posted a link on Facebook. Only after a flurry of comments did I notice, with the help of friends, that the average age of participants at the studyís outset was 76. So in spite of the shocking headline, that study doesnít come close to showing that my own blood sugar levels are at all related to dementia risk.
Can red meat cause cancer?
The study linking blood sugar to dementia was the first of its kind Ė thatís part of why it made headlines. In a more familiar case, strong consensus is emerging in the scientific community that excessive consumption of red meat increases risk of cardiovascular disease and cancer. This, too, has made the news.
And yet, proof of causation in the meat-cancer relationship is elusive.
Part of the problem is that itís really hard to prove anything in nutrition. In the case of red meat, conditions necessary for an effective randomized controlled trial are exceedingly difficult to assemble: a large sample size, a decades-long timeframe, a restrictive diet, and for a placebo group, really deliciously convincing fake steaks. Lovers and haters of seitan alike can agree that such conditions are unrealistic.
Not only are randomized controlled trials difficult to set up. Their very premise, the isolation of one variable, may not be appropriate for the study of nutrition. As Christopher Gardner, the director of nutrition studies at the Stanford Prevention Research Center, said in a recent Boston Globe Magazine feature, ďOne little thing at a time never makes a difference.Ē His point is that when we hold everything constant save for one variable, we lose sight of the cumulative, synergetic interplay of factors that promote health in combination Ė a balanced, natural diet, an active lifestyle, a safe social and physical environment, low stress levels, and so forth Ė that as individual factors, may not provide any measurable benefit. And then we try to determine whether a specific food, like garlic or, say, red meat, is good for you? Itís more complicated than that.
The impact of obfuscated research on consumers of food and information (us)
If itís nearly impossible to establish causation through randomized control trials, how are we supposed to know what to do? What is healthy? Which food pyramid should we follow? The latest one? The cacophony of doctors, journalists, health magazines, and our friends trumpeting medical advice can be confusing and frustrating. And by no means do all the doctors agree.
Many researchers donít let the complexity of science interfere as they publish newsworthy findings and make clinical health practice recommendations. Such recklessness has burned us before, as when doctors urged women to take hormone replacement therapy to guard against heart attacks based on so-called evidence from the Nursesí Health Study. The anticipated protective effect had not been verified by a randomized controlled trial, and later studies showed that hormone replacement therapy causes some women to suffer from increased incidence of heart disease, stroke, and breast cancer.
Navigating the nonsense
In the short term, itís unrealistic to expect the flood of misinformation, or misconstrued information, to abate. Anyone familiar with tenure in America understands that the pressure to publish is immense; prudence and patience might seem a laughable fantasy to a run-of-the-mill tenure-track professor with a career at stake. Health magazines have to fill their pages with exciting news. Authors have to sell books. They know we love those eye-popping headlines. We share the links, we buy the books. We drive the demand for sensationalized health news.
At the same time, the onslaught of conflicting information can overwhelm to the point of numbness. Thatís why some say, ďUntil they make up their minds, Iíll just eat what I want.Ē As camps of scientists, all with fancy degrees, bicker over whether meat, dairy, or carbs are bad for you, as they jockey to release the latest groundbreaking research, the public is apt to zone out. Studies say chocolate is good for me? Now itís bad for me? Whatever.
There are no clear answers and no policy initiatives designed to improve the situation. It might be impossible to prevent the cynical and confused from scrambling and misrepresenting the results of scientific research. At best, we can recognize these fundamental challenges of nutrition science and turn a critical eye to anything that seems too simple to be true.
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