Artificial sweeteners might be triggering higher blood-sugar levels in some people and contributing to the problems they were designed to combat, such as diabetes and obesity, according to new findings published Wednesday in the journal Nature.
Although the precise reasons behind the blood-sugar changes remain uncertain, researchers suspect that artificial sweeteners could be disrupting the microbiome, a vast and enigmatic ecosystem of bacteria in our guts.
In a series of experiments, researchers found that several of the most widely used types of non-calorie sweeteners in food and drinks — saccharin, sucralose and aspartame — caused mice to experience increased risk of glucose intolerance, a condition that can lead to diabetes.
“We are talking about very dramatic increases,” said one of the study’s co-authors, Eran Segal, a computational biologist at the Weizmann Institute of Science in Israel.
The same scientists also monitored what happened to seven human volunteers who did not typically use artificial sweeteners but were given regular doses of saccharin over the course of a week. Four developed significant glucose intolerance. Separately, the researchers analyzed nearly 400 people and found that the gut bacteria of those who used artificial sweeteners were noticeably different from people who did not.
“This huge and poorly understood microbial world, which resides in each and every one of us starting from birth, has been shown to play a fundamental role in many aspects of our physiology, as well as in [our] susceptibility to common human diseases,” said Eran Elinav, another of the study’s co-authors and an immunologist at the Weizmann Institute.
Wednesday’s findings add an intriguing new dimension to the long-running, contentious debate over the potential health benefits and risks of artificial sweeteners, which are among the most common food additives and are consumed by hundreds of millions of people around the globe.
While some past studies have found that the products pose no health risks and effectively help people cut calories and sugar intake, other research has suggested that certain artificial sweeteners might actually contribute to obesity and other problems, including cancer.
Segal and Elinav insisted that their findings are preliminary and shouldn’t be taken as a recommendation on whether people should reconsider using artificial sweeteners.
“We do not view that as our role,” Segal said. “Rather, as scientists, we simply point to the immense body of experiments that we carried out in both humans and in mice. . . . This study and these results should prompt additional debates and study into what is currently a massive use of artificial sweeteners.”
Elinav added: “This issue is far from being resolved.”
Lisa Lefferts, a senior scientist at the nonprofit Center for Science in the Public Interest, agreed. She praised the rigor behind Wednesday’s study and the “very provocative results” it produced, but she said the findings don’t negate past studies showing that people are more likely to gain weight when drinking sugar-sweetened beverages than when using artificial sweeteners.
Rather, she said, the various ways the scientists measured the effect of saccharin on the gut microbiota suggest a definite, if unresolved, link.
“We have more confidence now that there really is something going on, at least in animals,” Lefferts said. “What does that mean over the long term for the population? We still don’t have that answer.”
In addition, Lefferts and the study’s authors said people shouldn’t see the findings as a suggestion that sugar-sweetened drinks are somehow preferable to artificial sweeteners.
“We must stress, by no means are we saying that sugary drinks are healthy and that sugary drinks should be brought back as a healthy part of our nutrition,” Elinav said
The Food and Drug Administration has approved six different types of sugar substitutes, or “high-intensity” sweeteners, with the most recent coming this year. The three types included in Wednesday’s study involving mice — saccharin, sucralose and aspartame — are more commonly known by the popular brand names Sweet n’ Low, Splenda and Equal, respectively. However, the researchers relied primarily on saccharin in their mouse and human experiments.
Perhaps no sweetener has proven more controversial than saccharin, which was discovered not long after the end of the Civil War. In 1977, the FDA tried to ban saccharin because of safety concerns after studies showing that rats had developed bladder cancer after receiving high doses of the chemical sweetener.
Congress blocked that effort, instead passing legislation that required a warning label on products containing saccharin. In 2001, federal legislation removed the requirement for a warning label altogether.
The American Medical Association and the American Diabetes Association have cautiously backed the use of non-caloric sugar substitutes as a way to fight obesity and diabetes, saying that the products can be part of a healthy diet as long as the calories saved aren’t replaced by consuming more food over the course of a day.
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