SALT LAKE CITY, UTAH, U.S. — A University of Utah research study showed widely differing health outcomes between female mice fed a table sugar equivalent and others fed a high-fructose corn syrup analogue.
Responding to the study, the Corn Refiners Association (CRA) questioned whether the findings had relevance to human health.
The study, “Compared to sucrose, previous consumption of fructose and glucose monosaccharides reduces survival and fitness of female mice,” will be published in an upcoming issue of The Journal of Nutrition.
The study, funded by the National Institutes of Health and National Science Foundation, compared two groups of mice (male and female) that were fed for a period of 40 weeks a healthy diet in which 25% of calories came from processed sugars. One group ate a mix of fructose-glucose monosaccharides the researchers likened to what is in high-fructose corn syrup. The other group’s sugar was sucrose.
“Female mice on the fructose-glucose diet had death rates 1.87 times higher than females on the sucrose diet,” the researchers said. “They also produced 26.4% fewer offspring.”
No differences were found in males on the two diets when measuring survival, reproduction or the ability to compete for territory.
David Knowles of the CRA acknowledged that research studying the effects of sweeteners on rodents may attract media attention.
“But it (the University of Utah study) lacks scientific merit and mischaracterizes the effect of consuming HFCS,” he said.
Announcing research findings, the study’s authors made their case the broad importance of their rodent study.
“This is the most robust study showing there is a difference between high-fructose corn syrup and table sugar at human-relevant doses,” said Wayne Potts, a biology professor at the university and a lead author of the study.
He implied the findings may be used to explain the surge in health problems related to the diet over the past generation.
“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,” Potts said.
While recognizing that HFCS and table sugar contain roughly the same amounts of fructose and glucose, the researchers said in corn syrup, the two sugars are separate molecules, called monosaccharaides. By contrast, in table sugar, the fructose and glucose are bonded chemically — a disaccharide.
Knowles said the U.S. Food and Drug Administration (FDA) has examined this difference and dismissed its importance.
“Sucrose (table sugar) and HFCS are nutritionally equivalent and comprised of roughly 50% fructose and 50% glucose,” he said. “Fructose and glucose form a covalent bond in table sugar as opposed to HFCS. However, this difference is inconsequential. According to the FDA, ‘Once one eats (sucrose), stomach acid and gut enzymes rapidly break down this chemical bond.’
“Furthermore, the claim that consuming unbound fructose and glucose may uniquely affect female reproductive health is also highly questionable and irresponsible. 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.”
Knowles also noted that the F.D.A. has classified animal-based studies as “having low evidentiary value” and has concluded that consuming sugar and/or HFCS is safe when consumed in moderate amounts.
“The physiological and psychological differences between humans and rodents are so diverse that you simply cannot compare the two when determining the health impact of any food or ingredient,” Knowles said.
Earlier studies by the University of Utah scientists found health problems for both male and female mice.
The authors suggested the lack of a difference between the two male groups in the latest study “suggests sucrose is as bad for males as high-fructose corn syrup.”
The researchers also found no differences between the two cohorts of mice with regard to food intake, weight gain or glucose tolerance.
“We speculate that the different sugars could favor different microbes in the guts of mice,” said James Ruff, another lead author and a postdoctoral fellow in biology. “Other research has shown differences in bacterial communities in the gut to be associated with metabolic diseases in rodents and in humans. It’s possible one form of sugar causes more bacteria to get across your gut than another.”
The researchers said 13% to 25% of Americans eat a diet in which at least 25% of caloric intake comes from sugar.