I am an avid consumer of artificial sweeteners; my favorite is Splenda. An intriguing new study published in Nature yesterday found that the sweeteners boost blood glucose levels in mice. They suggest that the sweeteners may be contributing to the increase in human obesity and type II diabetes. How? The Israeli researchers think that the sweeteners don't themselves spike blood glucose; instead they somehow affect the microflora growing in the human digestive tract in ways that do that. The researchers found that consuming saccharin boosted glucose levels in four out seven human test subjects. From the abstract:
Non-caloric artificial sweeteners (NAS) are among the most widely used food additives worldwide, regularly consumed by lean and obese individuals alike. NAS consumption is considered safe and beneficial owing to their low caloric content, yet supporting scientific data remain sparse and controversial. Here we demonstrate that consumption of commonly used NAS formulations drives the development of glucose intolerance through induction of compositional and functional alterations to the intestinal microbiota. These NAS-mediated deleterious metabolic effects are abrogated by antibiotic treatment, and are fully transferrable to germ-free mice upon faecal transplantation of microbiota configurations from NAS-consuming mice, or of microbiota anaerobically incubated in the presence of NAS. We identify NAS-altered microbial metabolic pathways that are linked to host susceptibility to metabolic disease, and demonstrate similar NAS-induced dysbiosis and glucose intolerance in healthy human subjects. Collectively, our results link NAS consumption, dysbiosis and metabolic abnormalities, thereby calling for a reassessment of massive NAS usage.
With regard to the human experiment, Medscape (registration required) reports:
Artificial sweeteners caused changes in glucose tolerance in humans, as well, but only for some participants the investigators consider to be "responders." A group of 7 healthy volunteers who do not normally consume artificial sweeteners were given saccharin for 6 days at a dose that met the US Food and Drug Administration's maximum acceptable daily intake of saccharin for humans. No participants saw improvements in glucose tolerance, but 4 showed impairment.
Even before the experiment began, the microbial ecosystems from the 4 responders were different from those of the 3 nonresponders, suggesting their microbiome was somehow more susceptible. These results, said Dr. Elinav, "point to the personalized nature of our food responses and the need to understand this personalized effect in order to fight the metabolic syndrome, which as we all know, is one of the most common and serious epidemics in all history."
Bacteria from responders, sampled at the end of the trial, were able to induce glucose intolerance when introduced into germ-free mice (P < .02), whereas baseline samples from the responders (taken before they had consumed the artificial sweeteners) did not have this effect, nor did bacteria from the nonresponders.
The Washington Post reports that the researchers are not recommending that people shift toward eating sugar. The Post notes:
Researchers [Eran] Segal and [Eran] 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."
Yes, indeed. Keep in mind that this not an "I-told-you-so" moment for most food scolds who were chiefly claiming that the sweeteners increased the risk of cancer.
For what it's worth, my BMI is now 24.3 (although it's been as high as 30) and my blood glucose levels couldn't be more normal, so I will continue to dose my coffee and iced tea with Splenda. Of course, I may change my tune as further results are reported.
Hat tip to Felix, the first commenter to send me links to the study. Thanks to everyone else. Keep them coming.