Nutrition: Challenging ‘safe’ levels of sugar consumption

The consumption of comparatively low amounts of sugar decreases the competitive performance and reproductive output of mice, a study in Nature Communications reports. The finding suggests that even low levels of sugar intake, which are commonly considered ‘safe’ and do not cause large metabolic derangements, can have negative health effects in mammals.

Animal experiments that study the detrimental health effects of sugar usually involve the consumption of sugar quantities that far exceed those consumed by humans. Wayne Potts, James Ruff and colleagues fed mice a healthy diet with a modest amount of added sugar. According to the researchers, this amount of sugar - roughly equivalent to a human consuming a healthy diet plus three cans of soda (354 ml each) per day - is currently consumed by 13-25% of Americans. The mice, which showed minor metabolic defects, were then put in semi-natural enclosures where they competed for territory, resources and mating partners with mice previously fed a normal diet. As common strains of laboratory mice do not show natural territorial behaviors, the researchers conducted the study with wild house mice. They show that male house mice fed the sugar-enriched diet controlled 26% fewer territories and produced 25% less offspring, while female house mice experienced a two-fold increase in overall mortality.

The findings represent the lowest level of sugar consumption shown to adversely affect mammalian health. The researchers caution, however, that further studies are needed to delineate the mechanisms responsible for the observed changes in fitness and mortality.