High Fructose Corn Syrup May Cause Overeating

Listed as an ingredient in a wide variety of foods, high fructose corn syrup has no more calories than regular table sugar. It's the ratio of fructose to glucose that makes the difference. Table sugar has a 50/50 mix of fructose and glucose, while high fructose corn syrup has a 55 to 45 percent ratio. That difference changes the way our bodies metabolize them.

With a parallel between increasing rates of obesity and high fructose diets, researchers wanted to learn if high fructose diets are promoting insulin resistance and weight gain.

Participants included 20 healthy adults of normal weight who had magnetic resonance imaging (MRI) before and after drinking fructose or glucose. The small, blind study had a random order, crossover design. Blood tests measured circulating hormone levels and the volunteers were asked to rate their feelings of hunger, satiety, and fullness prior to and following the scan.

The resulting scans showed that after drinking something with fructose, the brain may fail to recognize the feeling of fullness that tells us to stop eating. While this limited study does not conclude that high fructose corn syrup causes weight gain or obesity, researchers believe it may be part of the problem.

"These findings suggest that ingestion of glucose, but not fructose, initiates a coordinated response between the homeostatic-striatal network that regulates feeding behavior," wrote the study authors.

Scans showed that drinking glucose "turns off or suppresses the activity of areas of the brain that are critical for reward and desire for food," said Yale University endocrinologist Dr. Robert Sherwin. With fructose, "we don't see those changes. As a result, the desire to eat continues – it isn't turned off."

Details of the study, which was supported by grants from the National Institutes of Health and the Yale Center for Clinical Investigation, are published in the January issue of Journal of the American Medical Association.

Last year, a study out of the University of Oxford and the University of Southern California, and published in the journal Global Public Health, revealed that the incidence of Type 2 diabetes was 20 percent higher in countries where the food supplies contained high fructose corn syrup.

Experts suggest avoiding fast foods and eating more home cooked meals so you have more control. Consumers should read the list of ingredients before purchasing pre-packaged foods and beverages. Unless the label says "100 percent organic," you should not assume that it has no high fructose corn syrup. When you really have a sweet tooth, honey and pure maple syrup are better choices.

References:

1. Page KA, Chan O, Arora J, Belfort-Deaguiar R, Dzuira J, Roehmholdt B, Cline GW, Naik S, Sinha R, Constable RT, Sherwin RS. Effects of fructose vs glucose on regional cerebral blood flow in brain regions involved with appetite and reward pathways. JAMA. 2013;309(1):63-70. doi:10.1001/jama.2012.116975.

2. Goran, M, Ulijaszek, S, Ventura, E. High fructose corn syrup and diabetes prevalence: A global perspective. Global Public Health. 2012,1-10

By Ian Duncan