High-fructose corn syrup prompts considerably more weight gain

Princeton researchers find that high-fructose corn syrup prompts considerably more weight gain

A Princeton University research team has demonstrated that all sweeteners are not equal when it comes to weight gain: Rats with access to high-fructose corn syrup gained significantly more weight than those with access to table sugar, even when their overall caloric intake was the same.

In addition to causing significant weight gain in lab animals, long-term consumption of high-fructose corn syrup also led to abnormal increases in body fat, especially in the abdomen, and a rise in circulating blood fats called triglycerides. "When rats are drinking high-fructose corn syrup at levels well below those in soda pop, they're becoming obese -- every single one, across the board. Hoebel lab

The first study showed that male rats given water sweetened with high-fructose corn syrup in addition to a standard diet of rat chow gained much more weight than male rats that received water sweetened with table sugar, or sucrose, in conjunction with the standard diet. The concentration of sugar in the sucrose solution was the same as is found in some commercial soft drinks, while the high-fructose corn syrup solution was half as concentrated as most sodas.

The second experiment -- the first long-term study of the effects of high-fructose corn syrup consumption on obesity in lab animals -- monitored weight gain, body fat and triglyceride levels in rats with access to high-fructose corn syrup over a period of six months. Male rats in particular ballooned in size: Animals with access to high-fructose corn syrup gained 48 percent more weight than those eating a normal diet.

"These rats aren't just getting fat; they're demonstrating characteristics of obesity, including substantial increases in abdominal fat and circulating triglycerides," said Princeton graduate student Miriam Bocarsly. The Princeton researchers note that they do not know yet why high-fructose corn syrup fed to rats in their study generated more triglycerides, and more body fat that resulted in obesity.

Hoebel lab

When male rats were given water sweetened with high-fructose corn syrup in addition to a standard diet of rat chow, the animals gained much more weight than male rats that received water sweetened with table sugar, or sucrose, along with the standard diet. High-fructose corn syrup and sucrose are both compounds that contain the simple sugars fructose and glucose, but there at least two clear differences between them.

First, sucrose is composed of equal amounts of the two simple sugars -- it is 50 percent fructose and 50 percent glucose -- but the typical high-fructose corn syrup used in this study features a slightly imbalanced ratio, containing 55 percent fructose and 42 percent glucose. Larger sugar molecules called higher saccharides make up the remaining 3 percent of the sweetener.

Second, as a result of the manufacturing process for high-fructose corn syrup, the fructose molecules in the sweetener are free and unbound, ready for absorption and utilization. The rats in the Princeton study became obese by drinking high-fructose corn syrup, but not by drinking sucrose. High-fructose corn syrup is found in a wide range of foods and beverages, including fruit juice, soda, cereal, bread, yogurt, ketchup and mayonnaise. In the future, the team intends to explore how the animals respond to the consumption of high-fructose corn syrup in conjunction with a high-fat diet -- the equivalent of a typical fast-food meal containing a hamburger, fries and soda -- and whether excessive high-fructose corn syrup consumption contributes to the diseases associated with obesity.

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