Critics of HFCS point out a correlation between increased usage of HFCS in foods and obesity rates in the United States over three decades. Some allege that HFCS is in itself more detrimental to health than table sugar (sucrose); others claim that the low cost of HFCS encourages overconsumption of sugars.
The Corn Refiners Association has launched an aggressive advertising campaign to counter these criticisms, claiming that high fructose corn syrup "is natural" and "has the same natural sweeteners as table sugar". Both sides point to studies in peer reviewed journals that allegedly support their point of view.
In his recent book In Defense of Food: An Eater's Manifesto, journalist Michael Pollan claims that the way that the body processes HFCS is different from the way it processes the glucose and fructose found in other sugars. Digesting sucrose requires the production of an enzyme called sucrase, which breaks the bond between the glucose molecule and the fructose molecule. Because the body regulates its production of sucrase, it can only digest sucrose at a certain rate. Because digesting HFCS does not require sucrase, the rate at which it is digested is not similarly regulated by the body.
Elliot et al., implicate increased consumption of fructose (due primarily to the increased consumption of sugars but also partly due to the slightly higher fructose content of HFCS as compared to sucrose) in obesity and insulin resistance. Chi-Tang Ho et al. found that soft drinks sweetened with HFCS are up to 10 times richer in harmful carbonyl compounds, such as methylglyoxal, than a diet soft drink control. Carbonyl compounds are elevated in people with diabetes and are blamed for causing diabetic complications such as foot ulcers and eye and nerve damage;
A study in mice suggests that fructose increases obesity. Large quantities of fructose stimulate the liver to produce triglycerides, promotes glycation of proteins and induces insulin resistance. According to one study, the average American consumes nearly 70 pounds of HFCS a year, marking HFCS as a major contributor to the rising rates of obesity in the last generation.
In a 2007 study, rats were fed a diet high in fat and HFCS and kept them relatively sedentary for 16 weeks in an attempt to emulate the diet and lifestyle of many Americans. The rats were not forced to eat, but were able to eat as much as they wanted; they consumed a large amount of food, suggesting that fructose suppresses the sensation of fullness.
Within four weeks, the rats showed early signs of fatty liver disease and type II diabetes. Shapiro et al. fed rats a high-fructose diet for six months and compared them to rats that had been fed a fructose-free diet. Although the rats that had consumed high levels of fructose showed no change in weight, when compared to the rats that had consumed a fructose-free diet, levels of leptin in the blood of rats fed a high-fructose diet indicated the development of leptin resistance.
When the rats were switched to a high-fat diet, the leptin-resistant rats, those fed a high-fructose diet, gained more weight than those who had not developed the resistance and had been fed a fructose-free diet.
Several studies funded by Tate & Lyle, a large corn refiner, the American Beverage Institute and the Corn Refiners Association, have defended HFCS. Forshee et al. concluded "that HFCS does not appear to contribute to overweight and obesity any differently than do other energy sources." Melanson et al. (2006), studied the effects of HFCS and sucrose sweetened drinks on blood glucose, insulin, leptin, and ghrelin levels. They found no significant differences in any of these parameters.
Monsivais et al. (2007) compared the effects of isocaloric servings of colas sweetened with HFCS 45, HFCS 55, sucrose, and aspartame on satiety and subsequent energy intake. They found that all of the drinks with caloric sweeteners produced similar satiety responses, and had the same effects on subsequent energy intake. Critics of HFCS, however, argue that the corn-industry funding of these studies leads to a possible conflict of interest, discrediting their results.
One much-publicized 2004 study found an association between obesity and high HFCS consumption, especially from soft drinks. However, this study provided only correlative data. One of the study coauthors, Dr. Barry M. Popkin, is quoted in the New York Times as saying, "I don't think there should be a perception that high-fructose corn syrup has caused obesity until we know more."In the same article, Walter Willett, chair of the nutrition department of the Harvard School of Public Health, is quoted as saying, "There's no substantial evidence to support the idea that high-fructose corn syrup is somehow responsible for obesity .... If there was no high-fructose corn syrup, I don't think we would see a change in anything important." Willett also recommends drinking water over soft drinks containing sugars or high-fructose corn syrup.
A pilot study reported that high-fructose corn syrup manufactured in the U.S. in 2005 was commonly tainted with mercury. The mercury appeared to come from caustic soda and hydrochloric acid, two chemicals used in the manufacture of high-fructose corn syrup that can, depending on their manufacturing process, contain traces of mercury. Mercury concentration in HFCS was as high as 0.570 μg/g (micrograms per gram).
Public Relations
Labeling as "natural"
In May 2006, the Center for Science in the Public Interest (CSPI) threatened to file a lawsuit against Cadbury Schweppes for labeling 7 Up as "All Natural" or "100% Natural", despite the presence of high-fructose corn syrup. Although the U.S. FDA has no general definition of "natural", CSPI claims that HFCS is not a “natural” ingredient due to the high level of processing and the use of at least one genetically modified (GMO) enzyme required to produce it. On January 12, 2007, Cadbury Schweppes agreed to stop calling 7 Up "All Natural". They now label it "100% Natural Flavors".
HFCS Advertisements
In September 2008, the Corn Refiners Association launched a series of United States television advertisements that claim that HFCS "is made from corn", "is natural" (changed from previously-stated "doesn't have artificial ingredients"), "has the same calories as sugar or honey", "is nutritionally the same as sugar", and "is fine in moderation". The ads feature actors portraying roles in upbeat domestic situations with sugary foods, with one actor disparaging a food's HFCS content but being unable to explain why, and another actor rebuking the comments with these claims. Finally, the ads each plug the Corn Refiners Association website. As HFCS is a controversial topic, parodies and criticisms of the ads have appeared on YouTube.
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