I’ve been reading (and enjoying) Michael Pollan’s book, The Omnivore’s Dilemma. I’m not going to go into a detailed review here, as you can find them on many other places on the web.

I was very intrigued by information about the amount of corn in the American food system (often as a result of industrialized agriculture, U.S. food policy and farm subsidies).

One of the things Pollan discusses is that scientists have been using mass spectrometers to determine how much corn is in a various items (a McDonald’s burger, a soda, a human being). To try to summarize:

Plants use carbon as part of photosynthesis. Most plants “breathe in” C-3, or three molecules of carbon. However, when plants open their stomata (“microscopic orifices through which plants both take in and exhaust gases,” Pollan, 21) to take in carbon, they lose water. Certain plants that can grow successfully in arid areas overcome this problem by taking in more carbon molecules per “breath.” These plants utilize C-4 (four molecules of carbon). Corn is one of these plants. In addition, because it’s taking in more carbon at once, corn can’t be as picky about what kind of carbon it uses. Thus, corn has a higher ratio of carbon 13 (a less desirable type of carbon) to carbon 12 (more desirable).

This may all sound confusing and complicated, but the basic outcome is this: carbon 13 has a certain molecular weight, and scientists can use tools (mass spectrometers) to measure that weight and the ratio of carbon 13 to carbon 12 to figure out how much corn is in different items.

For example, they can tell how much corn a cow has been fed. They can also tell how much corn we’ve ingested and incorporated into our biological make-up (from things such as corn oil, corn-fed beef and poultry, and high fructose corn syrup). According to Todd Dawson, a Berkeley scientist interviewed by Pollan, “We North Americans look like corn chips on legs” (Pollan, 23).

At this point what I really wanted to know was – what are your numbers? What peer-reviewed studies have scientists done? How have they gathered their data? I’m totally interested – tell me more!

Yet whenever I searched for Todd Dawson, corn, carbon 13, etc., all I found was that quote about “corn chips on legs.” Even Dawson’s website doesn’t have much information on nutrition – it’s more focused on mass spectrometer methodology as applied to other uses.

Citation needed.

After much searching, I found a Scientific American article about the subject, with references to a published peer-reviewed study, and another that’s ongoing.

Jahren [a geobiologist at the University of Hawaii] and her colleague Rebecca Kraft collected hamburgers, chicken sandwiches and fries from three separate Burger King, McDonald’s and Wendy’s locations in six U.S. cities: Baltimore, Boston, Detroit, Denver, Los Angeles and San Francisco. The scientists were looking for the amount of carbon 13 (13C), a variety of carbon with an extra neutron (known as an isotope) that makes its atom heavier.

…The result: 93 percent of the tissue that comprised the hamburger meat was derived from corn. In fact, only 12 samples from the entire country did not show this unique corn signature: all from a Burger King on the west coast. “My best guess is that it represents meat from another country,” Jahren says.

And all of the chicken, in addition to being sourced from just one company, Tyson Foods, Inc., had been fed an entirely corn diet, resulting in a chemical composition that was almost exactly the same from coast to coast. Jahren notes that the isotopic composition of this chicken meat varied from restaurant to restaurant and state to state less than if a sample were taken from just one farmyard-raised chicken.

Talk about the “uniformity of taste” that most fast-food restaurants strive for. (Which is why a McD’s hamburger tastes the same wherever you go – like cardboard and fat.)

Why should we care about the amount of corn in our diets? Cows cannot process corn well, and thus must be given large doses of antibiotics to keep them healthy until slaughter day. This leads to more drug-resistant bacteria in the world (“superbugs”). It also leads to lower amounts of Omega-3 fatty acids in corn-fed beef. Really, if you want more information on the myriad of problems, try reading the Omnivore’s Dilemma or watching Food, Inc. Want something more scientific? Check out the Center for a Livable Future at Johns Hopkins Bloomberg School of Public Health.

So just how much corn is in us? How has a corn-based diet affected the general population? Johns Hopkins researchers are trying to answer that question, and have done a number of studies about things such as the “Public Health Implications of Meat Production and Consumption” and “What Do We Feed to Food-Production Animals? A Review of Animal Feed Ingredients and Their Potential Impacts on Human Health.” (See Center for a Livable Future website for downloadable pdfs.)

According to the Scientific American article (published in November 2008),

Researchers at Johns Hopkins are now completing a study measuring the levels of carbon 13 in human blood, in an effort to understand how much of the corn in our meat and in the sweeteners (high fructose corn syrup) in our food and drink ends up in our bodies.

I think by “now completing,” they mean “completing and submitting for peer review.” At least, I have yet to find the study. If you find a citation, let me know.