Expert response from Bruce M. Chassy
Professor Emeritus of Food Safety and Nutritional Sciences, Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign
Friday, 11/07/2014 15:49
In recent years we have become more aware of autism and the suite of neurodevelopmental conditions sometimes called autism spectrum disorder. Medical research is not completely certain about the causes of autism, nor is there a magic pill that “cures” the disorder. On a personal level, this causes me a great deal of anxiety because I have a grandson who has been diagnosed with Asperger’s syndrome, one of the autism spectrum disorders. Although the incidence of autism sounds low when we read that only 6 per 1,000 people have it, that translates into almost 2 million cases in the United States alone, which in turn means tens of millions of families, relatives, friends, neighbors and teachers are indirectly touched by autism.
Experts are not convinced that the incidence of autism is rising. What is clear is that the condition is being diagnosed early on in a greater number of autism sufferers. There is an important difference between the rate of diagnosis and the rate of occurrence of autism. Part of the reason for increasing diagnoses may be attributed to understanding the need for early management and to the financial advantages to having a clear diagnosis that insurance and Medicare pay for.
What causes autism? Research shows that genetics play a major role. A number of specific genes have been implicated in autism, but exactly which come into play in each case and how they affect those with autism is not well understood. A recent study reports that 30 percent of autism cases may be attributable to spontaneous mutations that can occur in the DNA of the parents’ germ cells or even in the embryo once it is formed. In these cases, the baby does not really inherit the genes for autism from parents. This complicates the search for autism gene(s). When I hold my six-month-old grandson in my arms, I won’t know until he’s one or two years old whether he has inherited what might be called the “wrong” set of genes from his parents that will lead to autism, or if my grandson with Asperger’s syndrome inherited it from a parent.
Many other potential causes in addition to genetics have been claimed to cause or contribute to autism. To date, none has panned out. Scientific examination has failed to reveal a cause-and-effect relationship for most of the environmental, medical and dietary factors that have been cited as contributing to autism. Some potential causes have been easily dismissed by scientific research, while experts continue to debate others. For example, vaccination with the MMR vaccine has been claimed to cause autism. This belief was based on a single paper (never a good thing) published in the Lancet in 1998 by British physician Andrew Wakefield; a series of similar papers followed.
When the papers were found to have been based on fraudulent data and Wakefield was revealed to personally profit from the vaccination-autism connection, his papers were withdrawn, he was accused of scientific misconduct and his license to practice medicine was revoked.[2-3] As a result of this one fabricated paper, and in spite of the evidence of Wakefield’s fraudulent and unethical behavior, there is a widespread belief among otherwise well-educated and well-informed people that vaccines are somehow associated with autism and other adverse health effects. They are not!
To return to the question of whether GM crops cause autism, there is not a single peer-reviewed scientific publication that links autism to GM crops. There is also no scientific basis to understand how GM crops could cause autism. The technical way this is said is that there is no known biochemical, physiological or developmental mechanism by which this could happen. Moreover, there are many kinds of GM crops, and each of them is subjected to years of intense scrutiny by regulators at the U.S. Department of Agriculture, EPA and FDA before it is approved for human food and animal feed uses. To address the question directly, whole foods cannot be tested on brains directly.
The best we can do is feed experimental animals whole foods for a long period of time, or even several generations, and determine if any harm is observed. Hundreds of such studies have confirmed that GM crops are as safe as or safer than their conventional counterparts. Owning to the incredible sensitivity of modern instruments used in analytical chemistry, most scientists believe that whole-food feeding studies aren’t as powerful as the careful chemical composition studies that are done on GM crops. These studies show that the chemical composition of GM crops is no different than that of non-GM varieties of the same crop, so there is no scientific basis to expect them to produce autism or any other adverse effect.
The real problem with the question is that it is based on a common logical fallacy. Just because one event happens after another event doesn’t mean the first event caused the second event. Similarly, just because two things are changing at the same rate doesn't mean that there is a relationship between them. For example, sales of iPhones and organic food are increasing at about the same rate, but that doesn’t mean that one is causing the other or is related in any way. More important to remember is that it is not at all clear that the actual number of autism cases is going up.
So where did the idea that there is a connection between autism and GM crops come from in the first place? It’s possible that it was innocently asked by someone who observed a correlation between autism and GM crops, as stated in the question. It is, however, important to recognize that there is a small group of highly motivated anti-GM campaigners who pick up questions like this and broadcast them on the web, in print and even on TV. Have you watched Dr. Oz lately? He’s had Jeff Smith and many other anti-GM spokespeople on his show describing a possible link to autism, along with many other claims of adverse effects of consuming GM crops. Virtually all of what they say about GM crops is simply not true.[4-5] Why do they say these things? They have many motives, ranging from ideological to financial. In particular, the rapidly growing organic-food industry spends ten of millions of dollars per year on anti-GM propaganda.
1. Newschaffer CJ, Croen LA, Daniels J et al. The epidemiology of autism spectrum disorders [PDF]. Annu Rev Public Health. (2007) 28:235–58.
2. Taylor LE, Swerdfeger AL, Eslick GD. Vaccines are not associated with autism: an evidence-based meta-analysis of case-control and cohort studies. Vaccine. 2014;32(29):3623–9. doi:10.1016/j.vaccine.2014.04.085
6. Why Consumers Pay More for Organic Foods? Fear Sells and Marketers Know It. http://academicsreview.org/2014/04/why-consumers-pay-more-for-organic-foods-fear-sells-and-marketers-know-it/
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