Is Fructose Fuelling the Obesity Epidemic?

A new study has found that overweight adults that consume large amounts of fructose experience changes in body fat and insulin sensitivity that do not occur after glucose intake.

Researchers at the University of California School of Veterinary Medicine (Davis, CA, USA) compared the metabolic and endocrine effects of high-fructose corn syrup (HFCS) with sucrose and, in a subset of subjects, with pure fructose and glucose. A total of 34 men and women consumed three isocaloric meals with either sucrose- or HFCS-sweetened beverages, and blood samples were collected over 24 hours. Eight of the male subjects were also studied when fructose- or glucose-sweetened beverages were consumed.

The researchers found that in all of the subjects, 24-hour glucose, insulin, leptin, ghrelin, and triacylglycerol (TG) profiles were similar between days that sucrose or HFCS was consumed. In the men in whom the effects of four different sweeteners were compared, the 24-hour glucose and insulin responses induced by HFCS and sucrose were intermediate, between the lower responses during consumption of fructose and the higher responses during glucose. Sucrose and HFCS did not have substantially different short-term endocrine or metabolic effects. Unexpectedly, the researchers found that TG profiles after meals, which included HFCS or sucrose, were not intermediate but comparably high as after pure fructose.

"Consuming fructose-sweetened beverages during meals results in lower 24-hour circulating glucose, insulin, and leptin concentrations, and elevated triacylglycerol,” concluded lead author Peter Havel, D.V.M., Ph.D., of the department of molecular biosciences, and colleagues. "In male subjects, short-term consumption of sucrose and HFCS resulted in postprandial TG responses comparable to those induced by fructose.”

Pure fructose is found in fresh fruit, fruit juice, and preserves. However, fructose also enters our diets though HFCS (which has replaced sucrose as the predominant sweetener in beverages)--subsequently broken down in the body into 55% fructose and 45%--or via sucrose (ordinary sugar), which is also broken down into the same two sugars.


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University of California School of Veterinary Medicine