07/29/2011 04:32 pm ET Updated Sep 28, 2011

Passing Judgment on Genetically Modified Foods

I appreciate that the term "genetically modified"-- as in genetically modified organisms (GMO) or genetically modified food (GMF) -- conjures images of Frankenstein's monster (or at least, Frankenstein's monster's lunch), and makes people freak out. I know it makes people freak out, because I hear from them about it routinely -- some to ask my opinion, others to offer theirs.

Let's put the issue on trial before we reach a verdict. In a variation on the theme of evidentiary justice, I offer the defense perspective first and then the prosecution.

For the Defense:

I have two dogs, Bramble and Zouzou. I love them, they love me. They are definitely on my short list of BFFs. And they are, undeniably ... genetically modified. Every dog that isn't a wolf is genetically modified through a process better known as breeding. Breeding -- or more specifically, selective breeding -- is the controlled mating of individual members of a species to get the right combination of genes into their offspring. While the process may not involve test tubes, its effects are as dramatic and profound as anything a laboratory could cook up. Genetic modification through the process of selective breeding has turned wolves into Chow Chows, and Chihuahuas.

If you have cats that aren't ocelots, they, too, are the product of willful, genetic modification. As are our horses, goats, chicken, sheep and cattle. And that list gets us into the realm of food. The domestic chicken and cattle many of us eat are the product of many generations of selective breeding, i.e., genetic modification.

Nor is this characteristic limited to animals. Virtually every plant food we eat is a product of selective breeding, and often, more active manipulation of genes as well. In fact, Mendel -- the father of modern genetics -- revealed to us all the existence of genes by ... modifying them. Mendel famously cross-bred pea plants to show how their traits were passed along to the next generation. So in the 1850s, we had, in essence, genetically-modified peas.

Tomatoes, Romaine lettuce, pineapple, corn, watermelon and almost all other modern produce have their origins in nature, of course, but as eaten today are decidedly products of careful, selective breeding. This can at times simply involve selecting the plants with favored traits, but may involve hybridization as well -- the fusion of parts of one plant with another in order to get offspring with the desired traits of both. We owe many of our fruits and vegetables, along with our most beautiful flowers (e.g., "hybrid" roses), to such methods.

Seedless grapes are a product of willful genetic modification. Nectarines are the result of careful culling of a recessive gene in peaches that eliminates their eponymous fuzzy skin. Ever try a tangelo? It is the hybrid offspring of a tangerine and grapefruit. Genetic modification, to be sure.

Then there is the ultimate defense of genetic modification. In a word: sex.

Sex between humans is so veiled in mystique, intrigue and commercials for cologne -- it's easy to forget that it is an odd, unnecessary biological process. There are creatures -- yeast among the better known, but there are innumerable other examples -- that reproduce asexually. They just ... divide, with one parent cell becoming two offspring.

While most of us tend to take sex for granted (I mean, we take for granted the fact that there IS sex), scientists studying evolutionary biology do not. They have wrestled with the question: why does sexual reproduction exist at all? After all, it involves a great deal of trouble -- the obvious elements of which include finding, wooing and often competing for a mate. Asexual reproduction is a whole lot easier.

The conclusion reached by experts is that the principal reason sex exists at all is genetic modification! Sex mixes the genes of one parent with the genes of another to produce a genetically modified product we might be inclined to call ... a child. Or pup. Or cub. Or piglet.

Why is sex, and the resultant genetic modification, advantageous? While DNA is very, very good at reproducing itself, it isn't quite perfect. Mutations happen. With asexual reproduction, those mutations simply add up over time. Eventually, they reach a concentration in the gene pool of those offspring where they threaten their survival, either by making them dysfunctional, or by rendering them very vulnerable to some environmental challenge.

In contrast, sexual reproduction dilutes the effects of such mutations every generation. Whatever mutations have accumulated in the father's genetic pond are mixed with different mutation's in the mother's, and each dilutes to half the concentration and influence of the other. Only when the same "bad" gene is present in both ponds does this fail. A well known example is sickle cell anemia, resulting when the same recessive gene is received from both parents.

So, genetic modification is rampant in our lives -- from the kitchen, to the kennel, to the bedroom. Of course, modern genetic modification takes things a step further, by introducing genes from one species directly into the genome of another by use of laboratory methods. The Defense might contend that this is merely a variation on the theme of genetic modification going on since wolves were first bred into dogs, wild fowl into chickens and spindly native versions bred into beefsteak tomatoes, or huge, seedless watermelon. But let's hear from the prosecution.

For the Prosecution:

Modern methods of genetic modification differ not just in degree, but in kind, from the time-honored approaches of selective breeding. Part of what defines a species is that its members can mate and produce offspring only with one another. The willful introduction of genes from bacteria or amphibians (a gene for an anti-freeze like compound enables fish and frogs to survive through bitter winter, and could be used in crops to make them resistant to a sudden frost), into produce is not business as usual. It has the potential to introduce new proteins -- and new combinations of proteins -- into the food supply. The potential consequences of this are likely to include, but not limited to: food allergies, food sensitivities and intolerance, and auto-immune diseases.

But concerns go well beyond this list. Genes introduced into crops may result in compounds that are directly toxic to humans, producing consequences from infertility, to cancer -- to who knows what else.
And that's the point. We are playing with fire when we take the genetic makeup of foods directly into our own hands. We have the scientific acumen, but not the wisdom, to "play God" in this manner. High rates of fatigue, attention deficit disorder, gluten intolerance, chronic pain, irritable bowel syndrome and affective disorders may all relate in part to our manipulation of the food supply. These are chances we should not be taking.

Can we reach a verdict?

Honestly, I don't think so.

I gave the Defense more ink not because it's the more important case, but because it's the less obvious one. Concerns about genetic modification prevail -- so the Prosecution argument tends to be the better known.

Both arguments are valid. Modern methods of genetic modification are encumbered by the law of unintended consequences. Those opposed to genetically modified foods may derive strong support from the precautionary principle, which puts the burden of proof on the defense. Until we know that genetic modification is safe, we should presume it to be dangerous.

But we can't let it go at that, because by one means or another, almost our entire food supply is already the product of genetic modification. We are now a global population of 7 billion and rising, and in the absence of genetically modified crops, we would already be unable to feed ourselves. In some cases, of course, we already fail to do so. (As an aside, I encourage all those adamantly opposed to genetically modified foods to be as adamantly supportive of family planning and birth control.)

Genetic modification has the potential to help more people eat the recommended servings of vegetables and fruits by making crops resistant to frost, and produce resistance to spoilage -- thereby lowering costs and increasing availability. Genes that make crops pest-resistant could mean less use of pesticides, with benefits for human health and the environment alike.

So, we are likely left with a hung jury, because a summary judgment about genetic modification means reaching the same verdict about baby and bathwater. We really need to distinguish between them. Genetically modified foods can be -- and almost certainly already are in some cases -- overtly harmful. Abandoning genetic modification of foods, however, is impractical, and with a broad definition applied, impossible. It, too, could result in harm -- and missed opportunities.

Genetic modification is the means -- some versions are new and others are as ancient as sex itself. It is the ends we must judge, on a case-by-case basis.


Dr. David L. Katz;

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