Autism: a spectrum of risk factors that includes HFCS

Posted by
June 13, 2013

Last year the publication of a scientific paper in the peer-reviewed journal Clinical Epigenetics suggesting that autism was related to the consumption of high fructose corn syrup touched off a heated debate among those involved in the controversy over the likely causes and prevalence of autism.

The subject, after all, is a very sensitive one, and this particular study seemed to hit a nerve – or an awful lot of nerves. Such was the intensity of the reaction that two of its authors, Professor Renee Dufault and Dr. David Wallinga, prepared several statements explaining their work, plus a Q and A about “exploring the links between food and autism.”

What particularly got sparks flying was the researchers’ conclusion that “(a) comparison of autism prevalence between the U.S. and Italy using the Mercury Toxicity Model suggests the increase in autism in the U.S. is not related to mercury exposure from fish, coal-fired power plants, thimerosal, or dental amalgam but instead to the consumption of HFCS.”

Dufault and Wallinga subsequently explained that the paper “does not allege consumption of HFCS causes autism,” but rather “how it may be one important risk factor of many that contributes to a cumulative or ‘total load’ of risks” and that “this study finds that (HFCS) may be a risk factor that can contribute to the development of an autism spectrum disorder.”

The risks of HFCS consumption, the authors say, include mineral imbalances in the body, such as zinc, calcium and phosphorus depletion, which can result in the compromising of a key enzyme needed to eliminate organophosphate pesticides. Deficiencies in zinc can also impair heavy metal excretion, they point out.

Then there’s the potential of mercury exposure.

Dufault, while working at the Food and Drug Administration in 2005, discovered mercury residues in samples of HFCS. After presenting her findings to the FDA’s Center for Food Safety, she was instructed to discontinue her investigation, but after retesting, and finding mercury in nearly half the original samples, she and eight other scientists published the findings in the journal Environmental Health. (For the complete story on Dufault’s findings about mercury and HFCS see this 2009 article in Mother Jones.)

The mercury Dufault found in her samples results from a type of HFCS manufacturing process that uses mercury cell production, which can leave residues of the toxic metal in the finished product. While the Corn Refiners Association adamantly maintains that mercury-based technology in no longer used in the production of HFCS, Dufault states that “we are not aware of any independent verification of that fact.”

Oxidative stress: a high-fructose side effect

Another damaging effect of HFCS comes from its higher fructose content, explained Dr. Richard Deth, professor of pharmacology at Boston’s Northeastern University and a co-author on the autism paper, in a phone interview.

While “no one thing is causing autism,” he said, “we can think about the role of HFCS in particular because when this product, as opposed to natural sugar, is used, the fructose — in this case a higher proportion of fructose than normal — bypasses the first step of a particular pathway,” creating “a greater chance of oxidative stress” than sugar’s “more balanced situation.”

Deth said that in the case of autism, “it’s quite clear (from) lots of references” that it is associated with both “oxidative stress (which occurs when damaging oxidants exceed our antioxidant defenses) and low levels of antioxidants.”

Referring to the fructose content in sweeteners, rather than that which naturally occurs in fruits or vegetables, Deth said that the higher the fructose amount, the greater the chance of producing oxidative stress. “This shift toward (higher) fructose leaves us in an antioxidant-vulnerable situation,” he explained.

While the FDA’s legal limit on the fructose content of HFCS is 55 percent (10 percent higher than in sugar), studies have shown amounts in soft drinks to be as much as 20 percent higher, and a growing body of evidence has come to light that HFCS with highly fluctuating fructose amounts, including a mega-90 percent fructose version, is apparently being used by food and beverage manufacturers.

Such findings led Citizens for Health to file a petition last September with the FDA asking the agency to take action against manufacturers using HFCS with fructose levels above 55 percent, and in the interim, to require the actual amount of fructose it contains to be specified on product labels. (To sign and support that petition, click here).

“Oxidative stress,” Deth said, “is a common denominator” in autism that “many things cause and promote. But one can look for clues in the time course for increases in autism that began occurring around 1988. “So it has to be something that is quite broad and effects the whole population,” he noted.

Observing that the preponderance of HFCS in food products has more to do with “convenience” than concern for producing healthy food, he added, “now we can see that these things are not without consequence.”