January 21, 2014
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We often hear about studies conducted on animals that suggest how some substance—a food, drug, supplement or whatever—can either help or hurt us. But often the portions given to lab animals are so far beyond what any person would ever ingest that the findings are essentially meaningless in terms of human health.
Well, not this time! For a new study on sugar, researchers tackled the “out-of-proportion portions” problem by feeding mice a diet in which 25% of calories came from added sugars (those that are added to food during processing or preparation). That is not at all beyond the realm of reality—because an estimated 13% to 25% of Americans currently do get about one-fourth of their calories from added sugars.
Scary: The researchers uncovered some startling facts as to how all that sugar affects various aspects of life, from reproductive health to social behavior to mortality—and the news is not sweet. Here’s what you need to know about how sugar messes things up…
BIG SUGAR, BIG PROBLEMS
This study used “wild-derived” mice, not mice specially bred for laboratory use, because lab-bred animals do not display the natural behaviors that the researchers wanted to assess. The mice entered the experiment as soon as they were weaned from their mothers.
More on Sugar Dangers
All of the mice were given a highly nutritious chow. However, half of the mice were fed a higher-sugar diet in which 25% of calories came from added sugar (a mixture of fructose and glucose, just like table sugar and high-fructose corn syrup). The other mice were fed a chow with the same ingredients, except that cornstarch replaced the added sugar—so theirs was a lower-sugar diet. Both chows contained the same total calories and percentage of fat, carbohydrates and protein.
After 26 weeks on their respective diets, all of the mice were released into man-made habitats that mimicked the natural environment. The mice also received implanted microchips (like many pets get) to track their movements. When a microchip reader located within a habitat determined that a particular male mouse accounted for more than 75% of the appearances at a single location over a certain period of time, that mouse was considered to dominate the territory—a sign of competitive advantage.
Once inside the habitat, all of the mice were fed the higher-sugar chow because it wasn’t possible to keep them on separate diets when they were allowed to roam free—so the researchers were comparing the effects of the different diets from the previous 26 weeks. The in-habitat portion of the study continued for an additional 32 weeks, giving the mice time to establish their territories and breed, though only the original mice were assessed.
Results: There were no differences in body weight or insulin or triglyceride levels between the mice that had been fed the higher-sugar diet all along versus those that had been fed the lower-sugar diet for the first 26 weeks. But there were substantial differences in terms of…
Mortality. Female mice given the higher-sugar diet had nearly twice the death rate as females that received the lower-sugar diet. (Diet did not affect survival rates among males.)
Competitive ability. Male mice given the higher-sugar diet were at a competitive disadvantage socially, able to acquire and defend 26% fewer territories than males on the lower-sugar diet.
Reproduction. Male mice fed the higher-sugar diet sired 25% fewer offspring than males on the control diet. Female mice given the higher-sugar diet initially produced more offspring—but then their reproduction rate fell below that of the females on the lower-sugar diet.
OF MICE, OF MEN?
OK, mice are not humans. But the key point to understand is that, although the concentration of sugar fed to the mice on the higher-sugar diet was equivalent to what generally is considered “safe” for humans, it still had dramatic negative effects on these mammals. It is reasonable to assume that sugar might have equally harmful effects on people—especially since excess sugar consumption in humans already has been linked to the development of heart disease, diabetes, obesity, metabolic syndrome and fatty liver disease.
Annoyingly, the USDA guidelines on sugar are not clear—they recommend that no more than 15% of daily calories come from the combination of added sugar and “solid fats.” But it’s obvious that the USDA thinks that getting 25% of calories from added sugar is way too much. Fortunately, the American Heart Association recommendation is more straightforward, suggesting that added sugar should not exceed 100 calories per day for women or 150 calories per day for men.
Reality check: Even a single can of regular soda pop puts you over those limits, given that a typical 12-ounce cola contains about 40 grams (equal to about 160 calories) of added sugar.
Here’s help: To cut back on sugar—and still love what you eat—read I’m Kicking the Sugar Habit!” as well as the Facebook chat following that article…plus The One-Day Sugar Challenge.”
Source: James S. Ruff, PhD, postdoctoral researcher, department of biology, University of Utah, Salt Lake City. His study was published in Nature Communications.
