Are artificial sweeteners hurting our ability to regulate blood sugar levels? Let's ask our microbiome

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What if artificial sweeteners and sugar-free snacks and drinks are actually causing our bodies to lose control of the ability to regulate blood sugar levels? What if these sweeteners are a part of the cause of our societal obesity epidemic and not part of the solution?

That is exactly what is being suggested in a landmark study published yesterday in Nature. Researchers at the Weizmann Institute in Israel demonstrated that giving mice water laced with the chemicals in Sweet’N Low, Splenda, or Equal caused the mice to become glucose intolerant, resulting in the inability to metabolize sugars, due to alterations to the gut microbiomes.

People often consume these sweeteners with the rationale that the fewer calories consumed, the more successful they will be in losing weight. This study has shown that these chemicals may be doing more harm than good by altering the composition of our microbiomes.

After the mice receiving artificial sweeteners became glucose intolerant, which is often seen as a precursor to adult onset diabetes and obesity among other metabolic diseases, the researchers treated the mice with antibiotics to eliminate their gut bacteria.  The scientists found that with antibiotic treatment, the glucose intolerance was reversed showing the sweeteners caused the glucose intolerance. The researchers went one step further and transplanted bacteria from the mice treated with sweeteners into germ-free mice. Shortly after receiving the bacteria, the previously healthy mice became glucose intolerant, again telling us that the gut bacteria caused the glucose intolerance. 

As this work was done in mice, the team of scientists conducted a smaller study with human subjects to learn whether if the mouse studies would translate to humans.  Seven individuals who did not usually consume artificially sweetened food and drinks were given a week-long diet consisting of high levels of artificial sweeteners.  In that short amount of time, four of the seven individuals began to develop glucose intolerance. They then took fecal samples from the four individuals whose blood sugar levels were disrupted and put them into healthy mice. The healthy mice after receiving the human's gut bacteria also became glucose intolerant. 

While the sample size of the human experiment was small, the overall study is quite compelling and demonstrates the important impact that diet has on our microbiome. This is not a call for the general public to stop using artificial sweeteners as further research needs to be conducted.

With that said, it will be very interesting to see how the general public reacts to this paper.  Numerous studies have shown correlations between the microbiome and disease, but few studies have shown how such a small change in one's dietary habits could potentially have a major impact on an individual's future health outcomes. This is a story that we look forward to reading more about. 

Please email blog@MicrobiomeInstitute.org for any comments, news, or ideas for new blog posts.

The views expressed in the blog are solely those of the author of the blog and not necessarily the American Microbiome Institute or any of our scientists, sponsors, donors, or affiliates.

The great fecal microbiota transplant debate

An article was published today in the Atlantic that does a really nice job of describing the controversy surrounding fecal microbiota transplants (FMTs).  Basically, FMTs have been highly effective (>90% effective) in treating C. Difficile infections, and this efficacy has been even used as proof of the causal role of dysbiosis in C. Diff infection.  

The problem though, is that FMTs are currently unregulated, and the real question is how does the FDA regulate this new treatment, especially with how little is known about the microbiome.  The first question the FDA has to answer is whether or not fecal microbiota is a drug or a tissue.  Currently it is considered a drug but many common definitions would call it a tissue.

In addition, no one knows any long term consequences with FMTs, or what diseases to look for in donors, or how to screen FMTs at all.  Fecal microbiota is obtained just as you would imagine, through stool samples, and everything in that stool is transferred, the entire microbiota, including viruses.  It is a really complex issue that comes down to ethics, the responsibility of government, and the science of the microbiome.  Without guidance though, many have resorted to DIY FMTs which is not a good idea!

At the AMI we are aligned with the editorial written by a consortium of microbiome scientists, including our very own Marty Blaser and Rob Knight.  They support the FDA's cautious approach and note that past transplant procedures, like with blood, have resulted in unexpected disease transfer.  They also do see the benefit of FMTs and want to move forward with research to develop proper protocols, registries, and databases, as well as thorough clinical trials.  

A fellow non-profit here in Cambridge, Open Biome, based out of Eric Alm's lab at MIT, has created the first stool bank.  Organizations such as this will be essential to centralizing data and clinical outcomes, and we support their efforts.

Finally, drugs are being developed for C. Diff infection that are working.  Seres Health is a start-up in Cambridge, that has had great success in an oral treatment to C. Diff.  This may very well be the treatment for C. Diff in the future, but with so many diseases being linked to the microbiome, FMTs will again be at the forefront of therapeutics, even if they have not been successful for more complex diseases such as IBS and ulcerative colitis.

Please email blog@MicrobiomeInstitute.org for any comments, news, or ideas for new blog posts.

The views expressed in the blog are solely those of the author of the blog and not necessarily the American Microbiome Institute or any of our scientists, sponsors, donors, or affiliates.