Posted by Linda Bonvie
June 11, 2013
Since this blog was published in January, research done on rats by Dr. Francesco Leri, an associate professor of neuroscience and applied cognitive science at the University of Guelph in Ontario, Canada (which we talked about two weeks ago) has determined that high fructose corn syrup is indeed an addictive substance. Dr. Leri found that that the more he increased the percentage of HFCS, the more the rats worked to obtain it, which is “exactly what you notice with drug abuse, the same type of pattern.” Nor did satiating the rats on their regular chow make the craving for HFCS go away. When administered saccharine, however, the rats did not continue to crave it as they had with HFCS. To Leri, this indicated that “HFCS has effects that are beyond the sweetness in the mouth … effects on the brain.”
Back in the day, one of the most common admonitions from moms was “don’t eat that, you’ll spoil your appetite.” But if today’s kids are consuming foods and drinks with higher levels of super-sweet fructose, such as are found in high fructose corn syrup, the very opposite may be true.
According to the results of a new study published at the beginning of January in The Journal of the American Medical Association (JAMA), a brain on fructose just doesn’t know when to stop eating.
Drinking a fructose-sweetened beverage, the researchers found, created no sense of having ‘had enough’ giving a “completely different effect” than did the consumption of a beverage containing glucose (which makes up 50 percent of ‘real’ sugar).
“When we gave participants a fructose drink…there was not that fullness signal getting up to the appetite control region,” said study co-author Dr. Kathleen Page, Assistant Professor of Clinical Medicine at Keck School of Medicine of University of Southern California (USC).
Glucose, however, had the “opposite” effect, Dr. Page noted, in that it “basically inhibited those regions of the brain called the hypothalamus and reward regions…that regulate motivation for food.”
The study, conducted with 20 volunteers using MRI scans to view brain blood flow, was, Dr. Page said, “exactly” what had previously been seen in lab experiments with animals.
The Corn Refiners Association (CRA), quick to notice any mention of ‘overeating’ and ‘fructose’ in the same sentence, sent out a press release the same day the study was released saying that the study involved “massive doses of sugars” not consumed in “real life.”
“I don’t think that’s a true comment if you look at the amount (of sweetener) in a typical 20-ounce soda, which is 60 grams,” Dr. Page said. “We gave 75 grams so it’s not that much different.”
An ‘unbalanced’ formula with different results
The fructose in sugar, or sucrose, is a set amount of 50 percent with the other half being glucose. In high fructose corn syrup, however, research has shown the amount of fructose varies widely. And even though the CRA doesn’t talk about it, HFCS that is up to 90 percent fructose is apparently being sold for use in some foods and beverages.
“That’s why we are interested, we know there are differences in the way our bodies process fructose and glucose…there are reasons to believe that fructose is worse for us than glucose,” Dr. Page said, adding “the processing of HFCS, which could be made with higher percentages of fructose…has public health implications.”
While the FDA’s legal limit on the fructose content of HFCS is 55 percent (ten percent higher than sugar), some studies have shown amounts in soft drinks to be as much as 20 percent higher. Research by Dr. Michael Goran, director of the Childhood Obesity Research Center and professor of preventive medicine at the University of Southern California, found some of the HFCS-sweetened beverages he had analyzed coming in as high as 65 percent fructose. And a recent study in the journal Global Public Health by Dr. Goran pegged HFCS as an “additional contributing factor” to the development of diabetes, likely coming from the “more damaging” fructose in HFCS.
“It’s hard to know (fructose amounts) as foods don’t state their fructose content, just (total) sugars,” Dr. Page said, pointing out “most people aren’t aware of how much fructose they’re getting in these foods. If Dr. Goran’s study is true, we may actually be getting more fructose than we think.
“We know there are very different hormone responses, and these hormones signal to the brain to make us feel full,” said Dr. Page. “The body is responding differently to fructose than to glucose, we’re pretty confident with that.”
Dr. Page said she tells her patients a good strategy for healthier eating is to follow the recommendations of the American Heart Association, which include consuming fewer processed products. “You don’t find HFCS in natural foods,” she added.