Monday, May 16, 2011

Nutrition Science: An Oxymoron?

         I used to think that only a fool could experience much confusion about food and nutrition.  When I went to medical school, back in the days of leeches and wooden needles, nutrition was briefly covered in the biochemistry course.  Beyond that, it was pretty much, “Mmm, food good.  Eat food.” And, of course, “Fat people have no impulse control.”  This came from my freshman roommate, himself a skinny guy who went on to become a skilled and apparently compassionate bariatric surgeon.
         I’ve spent my life thinking that the equation was pretty simple.  If the number of calories taken in exceeded the caloric cost of running the body machinery, excess calories were stored as fat.  Weight loss occurred if we expended more calories than we had taken in, and weight gain occurred in the opposite circumstance.  Good nutrition meant taking in the right quantities of available “healthy food.”
         Now I’m beginning to see that food isn’t an easy or straightforward issue at all.  Perhaps all calories are not equal.  Perhaps all food is not equally good for us.  Perhaps even the “healthy food” that’s available isn’t so healthy, at least for the people who eat it.  For the economy? Maybe so.
The movie Food, Inc. seems to say that we’re guided by advertising and availability to eat what we eat because that’s where the money is for food and agriculture interests.  The once-hallowed FDA Food Pyramid of my youth seems to have been the result of a political process involving lots of lobbying by folks who wanted to be sure we continued to eat what they were being paid to produce – thus the heavy focus on grains.  Apparently, neither nutritionists nor health authorities had much to do with its production, though it has a profound effect on health.
         Individual voices stand out, sometimes out of proportion to the actual proven value of their message.  Gary Taubes’ article, “Is Sugar Toxic?” (NY Times, April 13, 2011) reiterates the story of nutritionist Ancel Keys from the University of Minnesota. Keys was such a strong proponent in the 1970s of his idea that dietary fat consumption was the best predictor of heart disease that he was able to discredit the equally-probably ideas of England’s John Yudkin, along with Yudkin himself.  Yudkin had argued that sugar consumption was linked directly to both the triglycerides of heart disease and the insulin levels of type II diabetes.  Keys’ powerful personality led to widespread acceptance of ideas about fat and heart disease that may have led us to adopt even more harmful high-carbohydrate diets to avoid fat.
         I’m reminded of the Gary Larson cartoon in which a shark in the water near a beach cups his fins around his mouth to yell, “Bear, Bear!!” as panicked bathers stampede into the water to escape.
         Casting caution to the winds, I have boldly asserted that I will wade into the morass of dietary information and sort out scientifically proven ideas from those that merely seem sensible.  In the process, I’ll identify those ideas without a shred of supportive evidence, and those that fly in the face of good sense.  When I’m done with that, it’ll be clear how we should all eat, and I’ll just jot it down and then we can get back to worrying about bigger things, like where Obama was born and whether autism causes global warming.
         Or not.
         Chris Mooney’s article on “Made-up Minds,” published originally in Mother Jones and excerpted in “The Week” (May 20, 2011), reminds us that reasoning is inseparable from emotion. We all tend to pull friendly information close and push threatening information away.  The fight-or-flight response, he says, applies not only to predators but also to information itself.
         What’s that mean?  It means that emotion may not have much bearing on scientific conclusions, but it certainly colors those conclusions to which we give credence, and those we’re willing to talk up.  We accept evidence that supports our views, and reject evidence that doesn’t.  In fact, we often reject as experts those whose conclusions, however well researched, don’t fit our pre-existing views.
         That’s a little awkward.  Does that mean that I can’t make an unbiased analysis of popular writing, looking for its scientific backing?  Will I filter out the stuff that doesn’t agree with my biases, even if it’s well-researched, and even if I think I’m being wonderfully even-handed?  Does that mean people shouldn’t trust me, either? Will my recommendations be just another set of biased ideas, based on that fraction of the literature that supports biases that I already have?
         Yeah, maybe. I’ll be authoritative, but not a “final authority.” I’m a seeker, an inquirer, an asker of questions.  When I present an idea as true, I really think it is.  Remember, however, that my pronouncement and $4.00 will get you coffee at Starbucks.  In other words, my idea is just that -- my idea, however well-spoken.  Even my objective judgments are difficult to separate from emotion, from my urge to affirm that the universe really does look the way I think it should look.
         Trust and verify.

No comments:

Post a Comment