By Sally Squires
Tuesday, February 6, 2007
Pick up a processed food item these days -- from bread and cereal to salad dressings, soft drinks and soups -- and you're likely to find a common ingredient: high-fructose corn syrup.
Call it the stealth sugar, because although foodmakers must list it as an ingredient, they are not required to say how much of it a product contains.
"Why is high-fructose corn syrup showing up in my food?" Lean Plate Club members often ask me. Some are so put off by the presence of this sweetener that they search for commercial products without it or make their own alternatives.
"I have been using the Wish-Bone spray-on" salad dressing, a Lean Plate Club member wrote during a recent Web chat. This person appreciated the convenience of the spray but didn't want the added sugar it contains. "Is there a recipe somewhere for homemade salad dressing that you can put in a spray-on bottle?" this LPCer asked.
High-fructose corn syrup is the floozy of the sugar world: It's sweeter and cheaper than table sugar but is viewed with distrust by some consumers. As a liquid, it's easy for food and beverage makers to use, especially for sweetening drinks. No wonder it has edged out the former leading sweetener: sucrose, or ordinary table sugar.
Since the introduction of high-fructose corn syrup in 1966, U.S. consumption has reached about 60 pounds per person per year. That rise has closely paralleled the obesity epidemic -- a fact that has led some scientists to suggest that there might be a link between the two.
Some aren't so sure. Michael Jacobson, director of the Center for Science in the Public Interest and a vocal critic of non-diet soft drinks, doesn't see high-fructose corn syrup as a particular evil. As far as he is concerned, it makes no difference whether beverages or foods are sweetened with table sugar or high-fructose corn syrup: He says both ingredients contribute plenty of added sugar and calories.
Now, new findings may help settle the debate.
First, a little Sugar 101. Made from corn starch, high-fructose corn syrup is a thick liquid that contains two basic sugar building blocks -- fructose and glucose -- in roughly equal amounts. Sucrose, familiar to consumers as table sugar, is a larger molecule that breaks down into glucose and fructose in the intestine during metabolism.
In the body, both fructose and glucose start a cascade of biochemical reactions. Glucose increases production of insulin by the pancreas, which enables sugar in the blood to be transported into cells, where it can be used for energy. Also boosted: leptin, a hormone that helps regulate appetite and fat storage. Glucose halts production of ghrelin, the so-called appetite hormone. When ghrelin levels drop, hunger declines.
Fructose, on the other hand, doesn't stimulate either insulin or leptin production and doesn't suppress ghrelin. It may also promote fat synthesis. That's why some scientists, including Peter Havel of the University of California at Davis, suggest that eating too much fructose could contribute to weight gain. But others note that studies have examined only pure fructose -- not the combination of sugars found in high-fructose corn syrup.
A new report pits the two sugars head to head in a group of 30 healthy, lean women. University of Rhode Island researchers twice admitted the women to a clinical metabolic unit, where all their food and beverages could be carefully controlled for 48 hours at a time. Thirty percent of daily calories were provided by beverages sweetened with either table sugar or high-fructose corn syrup. During the study, neither the investigators, whose research was sponsored by PepsiCo, nor the participants knew what the beverages contained.
The results show no differences in blood sugar, appetite hormones or hunger, the team reports in this month's edition of the journal Nutrition. That suggests no difference between the effects of what sucrose or high-fructose corn syrup do in the body -- at least over the short term.
Could there be other differences that didn't show up? "We don't know," says Kathleen Melanson, assistant professor of nutrition at the University of Rhode Island and lead author of the study. The next step is to study high-fructose corn syrup in men and in heavier women and to see if there are differences when the sweetener is used in foods rather than in beverages.
The equivocal results don't surprise Barry Popkin, professor of nutrition at the University of North Carolina at Chapel Hill and one of the scientists who have suggested a link between high-fructose corn syrup and the obesity epidemic. Popkin says he has heard that similar results are expected to be presented in April in Washington at the Experimental Biology meeting, a gathering of 15,000 scientists.
What does Popkin take from all of this? In terms of excess calories that fuel weight gain, all added sugar "is bad for you," he says, noting that high-fructose corn syrup may not be worse than any other kind.