Science and Politics of Food

January 29th, 2007

Posted by: Roger Pielke, Jr.

The New York Times Sunday Magazine has an excellent and provocative article on the science and politics of food by Michael Pollan. Here is an excerpt, but read the whole thing:

Most nutritional science involves studying one nutrient at a time, an approach that even nutritionists who do it will tell you is deeply flawed. “The problem with nutrient-by-nutrient nutrition science,” points out Marion Nestle, the New York University nutritionist, “is that it takes the nutrient out of the context of food, the food out of the context of diet and the diet out of the context of lifestyle.”

If nutritional scientists know this, why do they do it anyway? Because a nutrient bias is built into the way science is done: scientists need individual variables they can isolate. Yet even the simplest food is a hopelessly complex thing to study, a virtual wilderness of chemical compounds, many of which exist in complex and dynamic relation to one another, and all of which together are in the process of changing from one state to another. So if you’re a nutritional scientist, you do the only thing you can do, given the tools at your disposal: break the thing down into its component parts and study those one by one, even if that means ignoring complex interactions and contexts, as well as the fact that the whole may be more than, or just different from, the sum of its parts. This is what we mean by reductionist science.

Scientific reductionism is an undeniably powerful tool, but it can mislead us too, especially when applied to something as complex as, on the one side, a food, and on the other, a human eater. It encourages us to take a mechanistic view of that transaction: put in this nutrient; get out that physiological result. Yet people differ in important ways. Some populations can metabolize sugars better than others; depending on your evolutionary heritage, you may or may not be able to digest the lactose in milk. The specific ecology of your intestines helps determine how efficiently you digest what you eat, so that the same input of 100 calories may yield more or less energy depending on the proportion of Firmicutes and Bacteroidetes living in your gut. There is nothing very machinelike about the human eater, and so to think of food as simply fuel is wrong.

Also, people don’t eat nutrients, they eat foods, and foods can behave very differently than the nutrients they contain. Researchers have long believed, based on epidemiological comparisons of different populations, that a diet high in fruits and vegetables confers some protection against cancer. So naturally they ask, What nutrients in those plant foods are responsible for that effect? One hypothesis is that the antioxidants in fresh produce — compounds like beta carotene, lycopene, vitamin E, etc. — are the X factor. It makes good sense: these molecules (which plants produce to protect themselves from the highly reactive oxygen atoms produced in photosynthesis) vanquish the free radicals in our bodies, which can damage DNA and initiate cancers. At least that’s how it seems to work in the test tube. Yet as soon as you remove these useful molecules from the context of the whole foods they’re found in, as we’ve done in creating antioxidant supplements, they don’t work at all. Indeed, in the case of beta carotene ingested as a supplement, scientists have discovered that it actually increases the risk of certain cancers. Big oops.

2 Responses to “Science and Politics of Food”

  1. David Bruggeman Says:

    This seems very similar to the evolution of environmental chemical testing. Initially single chemicals and their exposure were examined, and eventually (if I’m remembering correctly) chemical interactions were a focus of study. However, the political and policy struggles associated with those changes aren’t evident here. Whether that’s a choice of the author or a reflection of the different field, I don’t know.

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  3. Margo Says:

    I see similarities with developing understanding in fluid dynamics. Initially, reseachers focus on understanding phenomena in special cases: inviscid flow, boundary layer flows, 1-D shocks, homogeneous isotropic turbulence. Each is examined as a separate effect.

    As each separate area is better understood, people try to put two phenomena together. Later researchers try to understand what happens in more and more complicated systems.

    (Similar things actually happen in engineering design. Better understanding of more complete systems permits more and more sophisticated designs.)

    With regard to developing scientific understanding, the need to begin by focusing on separate effects is likely just “the nature of the beast”.