Monday, April 18, 2011

Corn: Just Say No, Part 1

It's hard to beat the taste of fresh corn on the cob in the summer, I know. However, there are some things you should know about corn - things that might change your perspective on how much corn you want to allow into your diet.

Photo by Michelle Meiklejohn
I'm not going to get into the political aspects of corn grown as ethanol in this post or how bio fuels have affected food prices around the world. Or, how corn is one of the most nitrogen-intense crops to grow. Nor how environmentally damaging corn is as a monoculture crop that requires continuous pesticide application. I'm not going to tell you how corn requires a half a gallon of fossil fuel inputs per bushel, which contributes to the pollution of our waterways, aquatic dead zones, and human disease (1). Instead I want to look at how pervasive corn has become in our food supply and that of our livestock and the problems it has created (Part I), how damaging this is to our health (Part II), and what role corn as a genetically modified organism (GMO) has to play (Part III).

I think we can thank Michael Pollen and his book, The Omnivores Dilemma, for bringing to our attention the 'cornification' of our society. He details the history of corn for us and how it made its rise to prominence in our diet in just a few hundred years. It is amazing to learn that "there are some forty-five thousand items in the average American supermarket and more than a quarter of them contain corn." (2) We use corn flour for batter, corn oil for frying, corn starch for thickening, high fructose corn syrup for sweetening, xanthan gum for binding, caramel color for coloring, and the list goes on. It is estimated that the average American consume 56 lbs of corn and an additional 43 lbs of corn syrup per year (3). I'm guessing you had no idea you were eating so much corn, did you? It's hiding in our food and we are eating more corn than we realize.

Corn is not only in the products on the shelves, but it is also in the feed we give to the livestock -  chickens, cows, pigs and even fish - that we raise for meat consumption. Cattle are not designed to eat corn, they evolved on grass. Corn in their diet causes them all sorts of ugly health problems. As a consequence, antibiotics are routinely fed with corn to allow cattle to continue consuming the very food that is making them sick. This practice is courting disaster by encouraging the creation of antibiotic resistant strains of bacteria. Of particular concern is a strain of e-coli lethal to humans that lives happily in the normally neutral rumen of cattle. Our acidic stomach tends to kill this strain of e-coli, but with the increase in corn fed cattle, their rumen is becoming as acidic as our own and the e-coli is evolving to survive in this new environment (see Figure 1 and 2). How can we protect ourselves from this lethal bacteria when we consume contaminated meat? (3) The answer is, we can't.

Figure 1.

Figure 2.
The meat from grain-fed (which includes corn) cattle is not as healthy for us as a consequence. Conventionally raised beef has lower levels of vitamin E, beta carotene, conjugated linoleic acid, and omega-3 fatty acids. In fact, levels of omega-3 fatty acids can be two to four times lower in grain-fed beef (Figure 3). If you're eating fish for the healthy fatty acids, you might be surprised to learn that farmed fish fed on a diet of corn also affects their fatty acid ratio. Corn consumption moves the levels of the healthy omega-3 fatty acids down, and the levels of the not so good omega-6 fatty acids up - way up. Fish like tilapia are particularly affected with an omega-6 to omega-3 fatty acid ratio of 11:1, and salmon break even with a ration of 1:1 (4). Omega-6 is the inflammatory fatty acid, while omega 3 helps to reduce inflammation, so what we want to be seeing is this ratio in reverse. Diets high omega-6 fatty acids have been associated with inflammatory conditions, such as heart disease and high blood pressure, but also with mood and depression, memory, and behavioral problems.

Figure 3.
We should be aiming for a ratio of 30 percent omega-6 to 70 percent omega-3, but most Americans are getting a ratio much closer to 78 percent omega-6 to 22 percent omega-3 in their diet (7). Why has the fatty acid profile in our diet changed so much? Corn's own omega fatty acid content is a contributing factor (Figure 4). The more corn, corn bi-products and grain-fed livestock we consume, the higher our omega-6 ration will be. We are what we eat.

Figure 4.

If you stop to think about it, fish didn't evolve on corn, and neither did cattle, so why are we feeding it to them? Unless your ancestral heritage is of Native American descent, chances are your ancestor's digestive system only saw corn for the first time in the last three to four hundred years. What that means is that our bodies are not likely designed to eat it any more than cattle or fish. The corn grown today is vastly different from the corn grow 7,000 years ago, which had smaller ears and fewer kernels than today's modern varieties. Thanks to the advances in cross-hybridization, our food is now filled with corn. The problem is that we can't digest corn well. Corn and corn bi-products can be toxic to us and are contributing to far more than just skewed fatty acid ratios. I'll tell you why in Part II. 

(2) The Omnivores Dilemma, by Michael Pollen, p19
(4) The Omnivores Dilemma, by Michael Pollen, p82

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