By feeding mice sugar in doses that correspond to realistic amounts that we’d actually eat, researchers discovered that the fructose-glucose mix in high-fructose corn syrup is more toxic than sucrose, or table sugar. It reduced reproduction and shortened the lifespans of females.
The table sugar in baked goodies and the high-fructose corn syrup found in many processed foods contain roughly the same amount of fructose and glucose. However, in corn syrup, they’re separate molecules called monosaccharides, while in table sugar, fructose and glucose chemically bond to form a disaccharide. “When the diabetes-obesity-metabolic syndrome epidemics started in the mid-1970s, they corresponded with both a general increase in consumption of added sugar and the switchover from sucrose being the main added sugar in the American diet to high-fructose corn syrup making up half our sugar intake,” says Wayne Potts from the University of Utah in a news release.
He adds: “This is the most robust study showing there is a difference between high-fructose corn syrup and table sugar at human-relevant doses.” Up to a quarter of Americans consume a diet containing 25 percent of its calories in the form of added sugar—the stuff that’s tossed in during processing or preparation (and not the kind you’d find in fruit).
So, Potts and colleagues compared two groups of mice that were fed a diet with 25 percent calories from processed sugars: One group of mice ate a mix of fructose-glucose monosaccharides while the other group ate sucrose. After consuming their different diets, 160 unrelated mice were released into six “mouse barns” (pictured below)—room-sized, semi-natural environments where they can compete for food, mates, better territories, and nest boxes (blue tubs are the protected boxes, green trays are the less desirable open ones). The team monitored the mice using implanted radio chips and sensors at the feeding stations (vertical tubes) for 32 weeks.
The death rate of females on the fructose-glucose diet were 1.87 times higher than females on the sucrose diet, and they also produced 26.4 percent fewer offspring.
The team found no differences in male survival, reproduction, or territoriality, and they suspect it’s because both sugars are equally toxic to male mice. According to Potts, female mice undergo a bigger metabolic “energy crunch” during these studies compared to males: On the same day they give birth, they mate and conceive their next litter, which means they’re nursing their first litter while gestating the second.
“Our previous work and plenty of other studies have shown that added sugar in general is bad for your health,” University of Utah’s James Ruff says. “So first, reduce added sugar across the board. Then worry about the type of sugar, and decrease consumption of products with high-fructose corn syrup.”
The results from this toxicity test will be published in the Journal of Nutrition in March.
Images: Douglas Cornwall, University of Utah