Do you reach for natural sugar or artificial sweeteners like Splenda or Sweet'N Low? The science is split. Some studies show the fake stuff to be safe, while others raise serious concerns.
The latest study, published in the prestigious Nature journal, links artificial sweeteners to obesity and diabetes. Those are the very conditions the zero-calorie substitutes aim to prevent.
"For the longest time, we kind of considered these substances to be inert, or not really bother our body at all. We consume them, they have really no effect. We don't absorb them, so we're not getting calories out of them," said Dr. Anne Gilmore, a postdoctoral fellow and registered dietician at Pennington Biomedical Research Center. "This study suggests that maybe they are actually having a metabolic effect that we're not quite aware of."
Gilmore is part of a team of Pennington researchers that reviewed the study published in September.
Scientists in Israel gave one group of mice drinking water containing the most common artificial sweeteners: saccharin, sucralose and aspartame. The control group of mice was fed plain water and regular sugar water. After one week, that control group showed little change, but the mice that drank artificial sweeteners developed glucose intolerance.
Researchers determined that the problem developed in the gut – or intestines – which is home to a complex network of bacteria that science is only beginning to understand. The sweeteners altered that bacteria, and not in a good way.
"The dosage that they used of saccharin or Sweet'N Low in the mice drinking water is 5 mg per kilogram per day. That's within the Food and Drug Association's acceptable limit," Gilmore said. In humans, that translates to 7 – 10 packets of sweeteners per day, more than the average person consumes.
"It just comes down to moderation," Gilmore concluded. "Moderation being just 2 – 3 packets of artificial sweetener or 2 – 3 packets of sugar a day, maybe one 12-ounce can of soda."
The original researchers also tested their theory in a group of seven lean and healthy humans, giving each the maximum recommended dose of artificial sweeteners.
"It ended up that four of the people responded to artificial sweeteners, as far as changes in gut bacteria and in glucose response, and then three of the individuals didn't," Gilmore said.
The question now is, "Why?" Why do sugar substitutes have different effects on different people? The answer most likely lies in the gut and could become clear with more studies. In the meantime, experts say don't go crazy with the fake stuff, especially those who can tolerate sugar.
"One packet of sugar that you would see on the table right next to the Splenda or the Sweet'N Low packets is only going to have about 15 calories in it, so if you were having coffee or even tea and you just put one packet of sugar, it wouldn't be that big of a deal in the grand scheme of things of what you're eating with that meal," Gilmore explained.
As a registered and licensed dietician, Gilmore tells clients that artificial sweeteners are still generally regarded as safe, as long as they're used in moderation. Saying these chemicals have zero effect on the human body, however, is no longer a safe assumption. While a definitive link to cancer has never been established, artificial sweeteners have been shown to increase cravings for sugar.
Gilmore said larger human studies are needed to further explore how zero-calorie sweeteners interact with gut bacteria, potentially causing an increase in glucose levels. Until those are completed, it's best to take this preliminary research with a grain of sugar.
Pennington Biomedical is currently recruiting for a different gut bacteria study called STARCH. It focuses on the consumption of a special kind of fiber that's thought to better control blood sugar.
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