Female mice following a diet featuring a glucose-fructose mixture experienced adverse effects compared with mice on a diet featuring sucrose.
The study, scheduled for publication in The Journal of Nutrition, found that consumption of the fructose-glucose mixture led to reduced lifespan and reproduction in female mice. No differences in survival, reproduction or territoriality were observed among male mice, however.
For the study, mice followed a healthy diet with 25% of its total calories coming from either added fructose and glucose monosaccharides or from sucrose for the duration of 40 weeks, prior to being released into a controlled environment for 32 weeks of observation.
Experts estimate that around 13-25% of Americans consume a diet in which 25% or more of calories come from added sugars. According to study author James Ruff, 44% of added sugars in the American diet are sucrose, 42% are high-fructose corn syrup, and 14% are other combinations of fructose and glucose such as honey. In contrast, only 8% of global added sugar consumption involves high-fructose corn syrup.
Senior study author Prof. Wayne Potts says that it is important that the relative dangers of fructose and sucrose are debated, due to potential associations with changes in public health:
"[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."
The difference between high-fructose corn syrup and sucrose
While high-fructose corn syrup and sucrose contain around the same amounts of fructose and glucose, there is a difference in how they are arranged molecularly.
In corn syrup, fructose and glucose are separate molecules, known as monosaccharides, whereas in sucrose the two sugars bond chemically to form a disaccharide compound.
For their study, the researchers used a total of 160 unrelated house-type mice to ensure natural competition would occur. During the observational period of the study, the mice lived in custom-built "mouse barns" where they could compete for food, territory, and mates. Each barn was 377-square-feet, housing eight-10 male mice and 14-20 females.
While the mice ate either fructose-glucose or sucrose diets prior to being inserted into the mouse barns, when inside they all ate a fructose-glucose monosaccharide diet. The researchers state that it would have been impossible to enforce two different diets at this point due to integration between the two groups.
Female mice that had been on the fructose-glucose diet from the beginning of the study were found by the researchers to have death rates 1.87 times higher than females who had been on the sucrose diet. The fructose-glucose diet females also produced around 26.4% fewer offspring.
In contrast, the researchers observed no differences in the reproduction, survival and territorial behavior among the male mice on either diet. However, a previous study conducted in 2013 found that male mice were less likely to compete for territory or reproduce after following a fructose-glucose diet compared with a starch diet.
Researchers speculate their findings are associated with gut bacteria
Prof Potts states this finding "suggests sucrose is as bad for males as high-fructose corn syrup." The professor believes that the fructose-glucose diet may affect female mice more than male mice as they undergo a bigger metabolic "energy crunch" during studies such as these, caused by mating again straight after giving birth to a litter of offspring.
The researchers believe that whatever caused the different effects to the female mice on the fructose-glucose diet must have occurred at the point at which the monosaccharides were absorbed into the bloodstream or before. 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 humans. It's possible one form of sugar causes more bacteria to get across your gut than another."
The findings are not guaranteed to translate from mice across to humans, though they do serve to indicate the effects that added sugar could have upon biological systems.
"Our previous work and plenty of other studies have shown that added sugar in general is bad for your health," says Ruff. "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."
Last year, Medical News Today reported on a proposal from the World Health Organization (WHO) to reduce the advised daily sugar intake in a bid to tackle public health problems such as obesity and tooth decay.