Sensitive toxicity test used sugars in doses proportional to what we eat
When University of Utah biologists fed mice sugar in doses proportional to what many people eat, the fructose-glucose mixture found in high-fructose corn syrup was more toxic than sucrose or table sugar, reducing both the reproduction and lifespan of female rodents.
A 'mouse barn' such as the one shown here at the University of Utah is the heart of a new, sensitive toxicity test that allows house-type mice to compete in a seminatural environment so researchers can measure how exposure to sugar, medicines and other substances affects the mice in terms of their survival, reproduction and ability to hold territory. The blue tubs and green trays are nesting boxes, protected and unprotected, respectively. The feeding stations (vertical tubes) have sensor rings around them to detect transmitter chips implanted in male mice -- a way to determine which males hold which territories.
Credit: Douglas Cornwall, University of Utah
"This is the most robust study showing there is a difference between high-fructose corn syrup and table sugar at human-relevant doses," says biology professor Wayne Potts, senior author of a new study scheduled for publication in the March 2015 issue of The Journal of Nutrition.
The study found no differences in survival, reproduction or territoriality of male mice on the high-fructose and sucrose diets. The researchers say that may be because both sugars are equally toxic to male mice.
Both high-fructose corn syrup found in many processed foods and table sugar found in baked goods contain roughly equal amounts of fructose and glucose. But in corn syrup, they are separate molecules, called monosaccharides. In contrast, sucrose or table sugar is a disaccharide compound formed when fructose and glucose bond chemically.
Potts says the debate over the relative dangers of fructose and sucrose is important "because 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."
James Ruff, the study's first author and a postdoctoral fellow in biology, says, "Our previous work and plenty of other studies have shown that added sugar in general is bad for your health. 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 new study is the latest in a series that used a new, sensitive toxicity test developed by Potts and colleagues. It allows house mice to compete in the seminatural environment of room-size "mouse barns." Previous mouse studies with the test found harmful effects of inbreeding, the antidepressant Paxil and, last year, an added-sugar diet with fructose and glucose in amounts proportional to a healthy human diet plus three cans of soda daily. These health effects had been missed by conventional tests.
Potts and Ruff ran the new study with former University of Utah undergraduates Sara Hugentobler, Amanda Suchy, Mirtha Sosa, Ruth Tanner and Megumi Hite; and lab manager Linda Morrison. The other coauthors were nutrition researchers Sin Gieng and Mark Shigenaga at Children's Hospital Oakland Research Institute in California.
The research was funded by the National Institutes of Health and National Science Foundation.
New Findings Build on 2013 Sugar Toxicity Study
The 2013 study found that when mice were fed either a diet with 25 percent calories in the form of added fructose and glucose monosaccharides or 25 percent calories from starch, females died at twice the normal rate and males were a quarter less likely to hold territory and reproduce.
The new study compared two groups of mice that were fed a healthy diet with 25 percent calories from processed sugars. One group ate a mix of fructose-glucose monosaccharides like those in high-fructose corn syrup. 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.
The new study found no differences in males on the two diets in terms of survival, reproduction or ability to compete for territory. But Potts said the 2013 study showed male mice were a quarter less likely to hold territory and reproduce on the fructose-glucose mix compared with starch. That, combined with the new findings, "suggests sucrose is as bad for males as high-fructose corn syrup," he says.
Ruff says it also is possible that "other factors are more important than the differences between these two diets for the males" - possibly inherited differences in ability to hold territory.
Potts says 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. Sucrose is broken into fructose and glucose monosaccharides before the body absorbs it. So whatever caused the different mortality and reproduction in females on the two kinds of sugar diets, "it has to happen at the point of absorption or before - not once it is in the bloodstream, liver or brain," Ruff says.
"So we speculate that the different sugars could favor different microbes in the guts of mice. 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."
A Sugary American Diet
An estimated 13 percent to 25 percent of Americans eat a diet that includes 25 percent or more of calories in the form of added sugars - the percentage of added sugars consumed by mice in the new study. "Added sugars" are sugars added during food processing or preparation and not already naturally in food, like in a piece of fruit.
Ruff says that in the American diet, 44 percent of the added sugar is sucrose, 42 percent is high-fructose corn syrup and the remaining 14 percent includes honey, molasses, juice concentrates and agave - all of which also combine fructose and glucose (which also is known as dextrose). Yet worldwide, high-fructose corn syrup represents only about 8 percent of added sugar consumption, he adds.
Ruff says a number of previous studies in rodents and people tied pure fructose consumption to metabolic problems such as insulin resistance, obesity and abnormal cholesterol and triglyceride levels. He says those studies concluded high-fructose corn syrup was worse than sucrose, but most compared sucrose only to fructose instead of a more realistic fructose-glucose mix.
And "the few previous studies used much higher doses of sugars that are not particularly relevant to humans, and the effects were slight or small," Potts says.
How the Study Was Performed
The mice in the new study were unrelated, house-type mice, rather than inbred lab mice, because the former compete with each other naturally. For about 40 weeks, mice were fed either the healthy diet with 25 percent of total calories as added fructose and glucose monosaccharides or as sucrose.
Then 160 mice were released into six mouse barns to compete for food, territory and mates for 32 weeks. Each of the 377-square-foot mouse barns held eight to 10 male mice and 14 to 20 females.
Each mouse barn was divided by wire mesh into six territories, each with either an open or protected nest box. Males competed for the better territories and protected nests. Implanted radio chips and antennas at feeders kept track of where mice fed and thus the territories they occupied. The researchers periodically checked for and removed dead mice, as well as pups so they would not breed.
After eating different sugar diets before entering the mouse barns, all the mice ate the fructose-glucose monosaccharide diet while competing in the barns, where they roamed together and couldn't be kept on different diets. If there were harmful effects from the fructose-glucose diet before entering the mouse barns, they might be obscured if all the mice ate the sucrose diet once in the barns.
University of Utah Communications
75 Fort Douglas Boulevard, Salt Lake City, UT 84113
801-581-6773 fax: 801-585-3350
Lee J. Siegel | EurekAlert!
Transforming plant cells from generalists to specialists
07.12.2016 | Duke University
What happens in the cell nucleus after fertilization
06.12.2016 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Earth Sciences
07.12.2016 | Earth Sciences
07.12.2016 | Materials Sciences