Monday, July 23, 2012

If We Are What We Eat, We Aren’t What We Used To Be: Corn, Nuts, and Sugar

Anthropologists tell us that humans spent about one million years evolving as hunter-gatherers, and eating targets of opportunity such as nuts, fruits, greens, starchy roots and the occasional treat of meat or fish. Humans have spent about the last 10,000 years transitioning to a diet of domesticated plants and animals. Humanity has spent the last two or three generations converting their domesticated species into more efficient food producers. This has been accomplished by selective breeding, genetic modification, new types of nourishment, and altered agricultural methods. The bottom line is that we are now eating things that we never ate while we were evolving over those countless generations. We are messing with Mother Nature in ways we cannot possibly understand.

Michael Pollan raises this issue in The Omnivore’s Dilemma.

"Folly in the getting of our food is nothing new. And yet the new follies we are perpetrating in our industrial food chain today are of a different order. By replacing solar energy with fossil fuel, by raising millions of food animals in close confinement, by feeding those animals foods they never evolved to eat, and by feeding ourselves foods far more novel than we even realize, we are taking risks with our health and the health of the natural world that are unprecedented."

Of particular interest to Pollan is the degree to which corn has come to dominate our "industrialized" food chain.

"The great edifice of choice that is an American supermarket turns out to rest on....the giant tropical grass most Americans know as corn."

The ability to grow great quantities of corn cheaply and efficiently has created the need to make use of that excess.

"Corn is what feeds the steer that becomes the steak. Corn feeds the chicken and the pig, the turkey and the lamb, the catfish and the tilapia and, increasingly, even the salmon, a carnivore by nature that the fish farmers are reengineering to tolerate corn. The eggs are made of corn. The milk and cheese and yogurt, which once came from dairy cows that grazed on grass, now typically come from Holsteins that spend their working lives indoors tethered to machines, eating corn."

"Head over to the processed foods and you find ever more intricate manifestations of corn. A chicken nugget, for example, piles corn upon corn: what chicken it contains consists of corn, of course, but so do most of the nugget’s other constituents, including the modified corn starch that glues the thing together, the corn flour in the batter that coats it, and the corn oil in which it gets fried. Much less obviously, the leavenings and lecithin, the mono-, di-, and triglycerides, the attractive golden coloring, and even the citric acid that keeps the nugget ‘fresh’ can all be derived from corn."

Are there indications that we may be inflicting harm upon ourselves by our changing eating habits? We seem to be beset by a number of conditions whose incidence has recently grown to the point that the term epidemic is used. The list would include diabetes, food allergies, asthma, cardiovascular disease, obesity, cancer, autism, and even mental health.

Food allergies provide an interesting category. It is somewhat of a mystery that they even exist. One would have expected that the genetic variants that cause such allergic reactions to common foods would have been selected out by evolution. Perhaps their current rate of incidence can be interpreted as a result of our changed eating habits.

The allergy to nuts is one of the most common. An allergic response to nuts seems also to be correlated with an increased likelihood of being asthmatic. A fine article in The New Yorker by Jerome Groopman, The Peanut Puzzle, examines what is known about this condition. His article turns on the past belief that one could protect children from allergies by preventing encounters with the potentially dangerous substance, at least until their immune systems had matured.. This led mothers to follow the advice of doctors and avoid things like nuts during pregnancy in the belief that they were protecting their children.

This approach seems rather strange if one considers all those generations in which pregnant women ate whatever was available and then fed the same food to their infants—usually pre-chewed by the mother and ejected into the mouth of the child. There didn’t appear to be an attempt, or a need, to shield children from anything that was part of the food chain.

Groopman’s article describes the change of attitude that eventually crept into the medical profession as researchers came to conclude that gradual introduction of the sensitive material to a child was the best way to overcome, or outgrow an allergy. A complete about face in the recommendations to pregnant women took place in the US in 2008 and in the UK in 2010.

A recent study reported on by Kerry Grens for Reuters provides an apt conclusion to the controversy.

"In a study based on 62,000 Danish mothers, the children of those who ate peanuts and tree nuts while pregnant were less likely to develop asthma or allergies than the kids whose mothers shunned nuts."

It would seem that the genetic basis for allergic reactions to foods were not selected out by evolution so much as suppressed by eating habits. This example does suggest that changing what we ingest into our bodies can be a serious matter.

In searching for an example of changed eating habits, the curious case of sugar provides perhaps the most compelling and interesting example. Gary Taubes provided an absolutely fascinating article for the New York Times about a year ago: Is Sugar Toxic? Taubes describes the viewpoint of the medical researcher Robert Lustig who has been describing sugar with the terms "toxin" and "poison." His belief is that sugar should be considered in the same class as alcohol which can cause severe medical problems if taken in access. Taubes indicates that he has been following the literature on the effects of sugar consumption for the past decade and he concludes that Lustig is making a valid point.

Humans evolved getting their sugar in relatively small quantities via eating fruit. This type of ingestion means that the sugar was delivered slowly into the blood stream. Consider today when we consume much more sugar than our evolutionary ancestors, and we consume it in a form that provides rapid delivery. It should be recognized that sugars consist of a chemical combination of glucose and fructose.

"The fructose component of metabolized primarily by the liver, while the glucose from sugar and starches is metabolized by every cell in the body. Consuming sugar (fructose and glucose) means more work for the liver than if you consumed the same number of calories of starch (glucose). And if you take that sugar in liquid form — soda or fruit juices — the fructose and glucose will hit the liver more quickly than if you consume them, say, in an apple (or several apples, to get what researchers would call the equivalent dose of sugar). The speed with which the liver has to do its work will also affect how it metabolizes the fructose and glucose."

"In animals, or at least in laboratory rats and mice, it’s clear that if the fructose hits the liver in sufficient quantity and with sufficient speed, the liver will convert much of it to fat. This apparently induces a condition known as insulin resistance, which is now considered the fundamental problem in obesity, and the underlying defect in heart disease and in the type of diabetes, type 2, that is common to obese and overweight individuals. It might also be the underlying defect in many cancers."

"If what happens in laboratory rodents also happens in humans, and if we are eating enough sugar to make it happen, then we are in trouble."

Taubes believes there is sufficient evidence, albeit mostly circumstantial, to support grave concern for the effects of sugar consumption on our health. It should also be noted that around the turn of the current century the Department of Agriculture concluded that we were consuming about 90 pounds of sugar per capita each year.

Taubes’ article on sugar and its consequences demands a more detailed discussion. That will, hopefully, be presented soon. Let us merely conclude here that sugar, as we now consume it, was never encountered by our ancestors, and it has the potential to do great bodily harm if over consumed.

We are stuffing are bodies with constituents that have not stood the test of time. A powerful medication may require years of observation before we learn that there are undesirable consequences. The more subtle changes in our intake of nourishment may require generations to discover that we may have made a terrible mistake. We are participating in a massive experiment and don’t even realize it.


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