In John Tierney’s blog, Gary Taubes is very critical of nutrition researchers:
The last place you want a science to find itself is where obesity research is today, with hypotheses of causation that can explain none of the pertinent observations, but yet are believed so fervently that no one can challenge them without being ostracized or declared a quack.
Fair enough. But Taubes (and Tierney) make the usual mistake of being too critical and not enough appreciative. I figured the real wisdom would be in the comments, and I was not disappointed. Taubes thought physics functioned better than nutrition. One comment:
It’s not that the scientists [in physics and nutrition] are any more or less skeptical, or that it takes any longer for the truth to emerge, it’s that the public is more likely to be paying attention [to nutrition] in the meantime. And human beings as a group are extremely bad at reasoning under uncertainty.
Quite right. If Taubes and Tierney have trouble seeing the big picture (although Good Calories Bad Calories is a big-picture book) surely most people, and other journalists, do much worse. Another comment:
People like the old “correlation does not equal causation” slogan, but it’s not correct to translate that as “correlations are completely uninformative,”
Well put. (I blogged about this.) My favorite comment, however, was not wise:
Tierney stresses the errors and biases of nutrition science – but what of its successes? [Good start.] . . . As Tierney surely knows, there is a solid body of research that cumulatively demonstrates the positive effects of a balanced diet, lots of fresh fruit and veggies, avoidance of saturated fats, moderate consumption of calories and regular exercise. This is common sense, and science backs it up.
The history of nutrition teaches the opposite. The most helpful findings have not been “common sense”. Folate supplementation greatly reduced birth defects. Not common sense. Eat oranges to cure scurvy: Not common sense. Pellagra due to nutrition rather than infection: Not common sense. The whole notion of vitamins: Not common sense (deficiency diseases were attributed to poisons). “Common sense” approaches to losing weight, such as “moderate calorie intake”: Failed miserably.
It’s true that traditional foodways often turn out to be very healthy, but they can’t be called “common sense” because they vary so much from one place to another.
Thanks to Dave Lull and Tim Beneke.
Well said.
I see two problems with nutrition research:
* No hope of doing truly controlled experiments in humans. Yes, correlation tells us something, but it would be really nice to be able to say effect X happened because people ate more or less Y (for various values of Y — saturated fat, carbohydrates, etc.). In physics, an experiment can show which of two conflicting theories is correct, but similar experiments in nutrition are infeasible because you aren’t allowed to totally control a person’s food intake and see the long-term results.
* Terribly muddled communication with the general population. I’ve had “informed” people tell me that cane sugar is a “good for you” whole grain and that frozen vegetables are “bad for you”. The relentless focus on marginal optimization and fringe beliefs has caused people to miss the fairly uncontroversial big picture. Many different diet plans (including SLD and even the later phases of Atkins) can be made to fit with the “conventional wisdom” of Willett’s food pyramid.
I agree. Except you can do well-controlled experiments when a nutrient affects the brain because you can maintain control for a short period of time and the brain reacts rapidly. My omega-3 research is all about that.