University of Utah biologists fed mice sugar in doses proportional to what many people eat, and found the fructose-glucose mixture found in high-fructose corn syrup (HFCS) may be more toxic than sucrose or table sugar.

According to the recent study, HFCS reduced both the reproduction and lifespan in female rodents. However, the study found no differences in survival, reproduction or territoriality of male mice on the high-fructose and sucrose diets. Instead, researchers speculate both sugars may be equally toxic to male mice.

Both HFCS and sucrose contain roughly equal amounts of fructose and glucose. But in corn syrup, they are separate molecules, called monosaccharides. In contrast, sucrose is a disaccharide compound formed when fructose and glucose bond chemically.

HFCS has been routinely blamed for a slew of adverse health effects, including being a key contributor to the obesity epidemic, according to Food Product Design’s Digital Issue, “Spotlight on Sweeteners.” However, in many cases, research cannot confirm fructose is the culprit.

The present study is the latest in a series that used a new, sensitive toxicity test developed by biology professor and senior author of the study Wayne Potts and colleagues. It allows house mice to compete in the seminatural environment of room-size “mouse barns.”

 
For the study, two groups of mice were fed a healthy diet with 25 percent calories from processed sugars. One group ate a mix of fructose-glucose monosaccharides like those HFCS. The other group ate sucrose.

Female mice on the fructose-glucose diet had death rates 1.87 times higher than females on the sucrose diet. They also produced 26.4 percent fewer offspring. However, researchers found no differences in males on the two diets in terms of survival, reproduction or ability to compete for territory.

According to Potts, female mice that ate the fructose-glucose mixture may be more likely to die than male mice because they undergo a bigger metabolic “energy crunch” during such studies: on the day they give birth, they mate and conceive the next litter, so they are nursing their first litter while gestating a second litter.

Regardless of sex, the researchers also found no difference between mice on the two diets when it came to food intake, weight gain or glucose tolerance. Researchers speculate since sucrose is broken into fructose and glucose monosaccharides before the body absorbs it, whatever caused the different mortality and reproduction in females, “has to happen at the point of absorption or before—not once it is in the bloodstream, liver or brain,” said James Ruff, the study’s first author and a postdoctoral fellow in biology, adding that the different sugars could “favor different microbes in the guts of mice.”

However, according to a statement by the Corn Refiners Association (CRA), the difference in structures of sugar and HFCS “is inconsequential.”

“Fructose and glucose form a covalent bond in table sugar as opposed to HFCS,” the statement said. Per FDA, “Once one eats [sucrose], stomach acid and gut enzymes rapidly break down this chemical bond.”

Further, in the statement, CRA notes the claim made by researchers that consuming unbound fructose and glucose may adversely affect female reproductive health is “highly questionable and irresponsible.” The statement continues: “Human reproduction is regulated by the endocrine system and the overwhelming scientific evidence shows no difference between the effects of high fructose corn syrup and sucrose on the endocrine system in humans.”