The soaring rates of diabetes in the United States and many other developed countries over the past three decades has been generally blamed on obesity. We're getting fatter, and that puts us at risk for developing diabetes. But a new theory suggests that the diabetes epidemic is not just a matter of eating too much and moving too little. It could have more to with some components of our diet.
High-fructose corn syrup, that staple of many soft drinks and packaged snack foods, is associated with a higher prevalence of diabetes regardless of obesity, according to a new study. The paper raises the question of whether our bodies respond to a steady diet of high-fructose corn syrup by becoming resistant to insulin and developing the inability to process sugar—which results in diabetes.
The paper strikes at the heart of an ongoing controversy in the nutrition world about whether high-fructose corn syrup is just another sugar, like it's cousin sucrose, or acts differently in the body. That debate is far from settled.
"It's controversial," Dr. Michael I. Goran, professor of preventive medicine at the University of Southern California and a co-author of the paper, told TakePart. "There are strong feelings on both sides."
Goran's paper, co-authored with researchers from the University of Oxford, found that countries that use high-fructose corn syrup in their food supply had a 20 percent higher prevalence of diabetes than countries that did not use the substance. Even when researchers controlled for obesity rates and total sugar intake, the presence of high-fructose corn syrup in the diet significantly boosted diabetes rates. The paper appears in the journal Global Public Health.
"Fructose may contribute to obesity and obesity contributes to diabetes. We are not denying that," says Goran, director of the Childhood Obesity Research Center and codirector of the Diabetes and Obesity Research Institute at the Keck School of Medicine at USC. "But not all obese people are diabetic. On top of that, there is an independent affect of fructose on diabetes over and above what you get from obesity."
The authors examined data from 42 countries. The United States has the highest per capita consumption of high-fructose corn syrup at 55 pounds per year. The second highest is Hungary, with an annual rate of 46 pounds, per capita. Canada, Slovakia, Bulgaria, Belgium, Argentina, Korea, Japan and Mexico are also heavy users of the substance.
Countries that have lower consumption rates include Germany, Poland, Greece, Portugal, Egypt, Finland and Serbia. And countries that average only about one pound per person annually include Australia, China, Denmark, France, India, Ireland, Italy, Sweden, the United Kingdom, and Uruguay.
The study found that countries with higher use of high-fructose corn syrup had an average prevalence of type 2 diabetes of 8 percent compared to 6.7 percent in countries not using the sugar.
About 6.4 percent of the world's population is diabetic, a rate that is expected to rise to 7.7 percent by 2030, according to the paper. In the United States, 8.3 percent of adults are diabetic.
"What was different about our study is we took a much broader, macro look at the issue," Goran says. "We did that because there is no other good way to look at it. It's really impossible to know how much is consumed by an individual because it's so ubiquitous in the food supply and in unknown amounts."
The study has limitations, he notes. The research only looks at high-fructose corn syrup produced in that country and does not take into account imports.
High-fructose corn syrup is a manmade sweetener that is a popular ingredient in processed foods like ketchup, crackers, cookies and salad dressings. It's found in many types of soft drinks. According to the U.S. Department of Agriculture, domestic production of the substance increased from 2.2 million tons in 1980 to an average of 9.2 million tons during the 2000s "as high fructose corn syrup replaced more expensively priced sugar in a variety of uses."
Diabetes rates in the United States began to climb at about the same time that high-fructose corn syrup began playing a bigger role in the food supply. But how high-fructose corn syrup might contribute to diabetes is unknown. Some nutritionists contend that the substance is chemically similar to table sugar and is metabolized similarly in the body. But others say that high-fructose corn syrup causes a different biological reaction than does exposure to sugar. Fructose is also sweeter, which may lead consumers to crave it more or consume more of a food item containing fructose.
"Even in the scientific community, I hear people say all the time that there is no difference" between fructose and sucrose, Goran says. "They are clearly not identical. The next question is how they are different? One of the main things that make them different is in their most popular form, high-fructose corn syrup has more fructose in it, at least 10 percent more. The higher fructose makes it sweeter, so people will probably consume more of it. It's cheaper to make and you need to add less."
The food industry is sensitive to the idea that fructose is somehow worse than sugar. In a statement, the Corn Refiners Assn., said the study "uses a severely flawed statistical methodology and ignores well established medical facts to 'suggest' a unique link between high fructose corn syrup (HFCS) and type 2 diabetes...Most importantly, Dr. Goran’s newest attack on HFCS fails to account for widespread agreement among scientists and medical doctors that HFCS and sucrose (table sugar) are nutritionally equivalent."
High-fructose corn syrup is eyed suspiciously be some consumers, however. In May, the Food and Drug Administration turned down a request by the Corn Refiners Assn. to allow them to use the term "corn sugar" on labels instead of high-fructose corn syrup.
Goran is in favor of stricter labeling regulations regarding high-fructose corn syrup. The type of sugar in a product should be clearly labeled in the same way that various types of fats are specified on food labels, he argues.
"Trans fat labeling is a good analogy," he says. "The public totally buys into the trans fat thing. Trans fats are bad and omega 3 fats are good. You don't need to understand the chemistry of that. It's just good fat and bad fat. I think the label should indicate the amount of fructose and let the consumer decide."
Question: Is high-fructose corn syrup worse than regular table sugar? Tell us what you think in the comments?
Shari Roan is an award-winning health writer based in Southern California. She is the author of three books on health and science subjects.