Study: high-fructose corn sweeteners partly responsible for obesity
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By coupling extensive US Department of Agriculture food consumption data and their own analyses with previous research, nutrition experts have concluded that high-fructose sweeteners made from corn are partially responsible for the growing national obesity epidemic.
Fueling the epidemic
Introduction of the sweeteners, which are cheaper to produce and use in food manufacturing than cane and beet sugars, corresponded closely time-wise with the epidemic's start, the researchers say. Several other biological factors associated with high-fructose corn sweeteners appear to boost their negative effects on Americans' waistlines too.
The scientists are Dr George A. Bray, Boyd professor at the Louisiana State University System's Pennington Biomedical Research Center, and Barry M. Popkin and Samara Joy Nielsen, professor and doctoral student, respectively, in nutrition at the University of North Carolina at Chapel Hill. At UNC, nutrition is a department shared between the schools of public health and medicine.
Their report appears in the April 2004 issue of the American Journal of Clinical Nutrition.
"Body weights rose slowly for most of the 20th century until the late 1980s," Bray says. "At that time, many countries showed a sudden increase in the rate at which obesity has been galloping forward."
The usual suspects for burgeoning fatness in this country have been the increase in US food intake and a drop in physical activity, he says. To examine the potential role of excess eating, Bray, Popkin and Nielsen analyzed USDA consumption records from 1967 to 2000.
"In examining this data, the importance of the rising intake of high fructose corn syrup was obvious," Bray says. "It did not exist before 1970. From that point, there was a rapid rise in this country in its use during the late 1970s and 1980s coincidental with the epidemic of obesity."
The extra sweetness of solutions such as soft drinks and fruit beverages containing glucose and fructose appears to boost caloric intake sharply, the scientists concluded.
"We know that high fructose corn syrups now provide the entire source of calories in these beverages," Bray says. "Although this data does not prove a causal link, the timing of their introduction and the known differences in sweetness between fructose and sucrose make corn syrups very strong suspects in the increased beverage intake that has occurred over the past 25 years."
Americans can no longer speak of sugar consumption and assume that it includes only products from sugar cane and sugar beets, Popkin says.
"We now know that high fructose corn sweeteners represent more than 40 percent of all caloric sweeteners added to foods and beverages and are the sole caloric sweetener in soft drinks in this country," he says.
Using what they called very conservative estimates, the researchers showed that more than 132 calories per day for all Americans age two and older come from the corn sweeteners, Popkin says.
"More amazing is that among those American who consume a lot of soft drinks --the top 20 percent of consumers -- more than 316 calories per day come from high fructose corn sweeteners," Popkin says. "Our work shows a very strong linkage between intake of the corn sweeteners and obesity trends in this country.
"Moreover, we know that the fructose does not affect appetite," he says. "Unlike glucose, it does not affect insulin secretion and has absolutely no affect on the feeling of satiety linked with consumption of most foods. In other words, we know that calorically sweetened beverages may enhance caloric over-consumption by their actions in the body."
Not only are digestive and absorptive processes different for glucose and fructose, but the former, unlike the latter, helps satisfy hunger pangs by sending signals to the brain, the scientist says.
Fructose also facilitates formation of fats more readily than glucose does.
Because the health issues are so important, more studies are needed to verify or refute their theory, the authors say.
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"We believe that an argument can now be made that the use of high fructose corn sweeteners in beverages should be reduced and replaced with alternative non-caloric sweeteners," they wrote. "If the intake of calorically sweetened beverages is contributing to the current epidemic, reducing their availability by removing soda machines from schools would be a strategy worth considering, as would reducing the portion sizes of commercially available sodas."
Manufacturers produce fructose, which is sweeter than sucrose, using an enzyme known as glucose isomerase to convert the starch in corn efficiently -- first to glucose and then to fructose.
Consumption of high fructose corn sweeteners increased more than 1,000 percent between 1970 and 1990, far exceeding changes in intake of any other food or food group, Popkin says.
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