By Eric Moorhead 

There’s big news out – artificial sweeteners are toxic to your gut microbiome. You haven’t heard? Allow me to share some headlines from the last week:

Artificial Sweeteners Are Bad For Your Gut Microbiome, A New Study Shows

ARTIFICIAL SWEETENERS ARE TERRIBLE FOR YOUR HEALTH, SCIENCE SAYS

ARTIFICIAL SWEETENERS, SPORT SUPPLEMENTS COULD BE TOXIC TO YOUR GUT, STUDY SAYS

Except, artificial sweeteners probably aren’t killing your gut microbiome— at least not according to the research article on which these headlines are based. Published in Molecules, owned by publishing house MDPI, the manuscript is titled “Measuring Artificial Sweeteners Toxicity Using a Bioluminescent Bacterial Panel.” Not a very compelling title, I know.

Here’s what the science in this paper can tell us— if you treat certain strains of bacteria with increasing concentrations of artificial sweeteners in vitro, they die. (This shouldn’t come as terribly surprising. I worked on new drug candidates for drug-resistant bacterial infections for a few years— enough of anything will kill bacteria in vitro. Whether this in vitrotoxicity corresponds to in vivo toxicity remains unclear, as any medicinal chemist worth their weight will tell you.)

Of interest, the researchers in this paper chose a genetically modified form of E. coli. It should be noted that this strain of genetically modified E. coli does not exist in our gut.

So, at its core, this article says that high concentrations of artificial sweeteners are toxic to a genetically modified strain of E. coli in a laboratory setting.

I would argue that this study doesn’t prove anything conclusive about artificial sweeteners and their potential impact on the gut microbiome. There are a few keys gaps in data that would be needed to answer these questions. For instance:

-Do the levels of sweeteners that cause toxicity correspond with levels of exposure of, say, when you drink a diet soda?

-Are artificial sweeteners toxic to the strains of bacteria known to be found in our gut?

-Do artificial sweeteners exhibit any toxicity in vivo (in a living system, rather than in the laboratory)?

However, the lack of data hasn’t stopped the authors from concluding that their results allow them to propose supposed toxicity to the gut microbiome. I would argue that the conclusions reached by the authors are incorrect, and if I were a reviewer of this manuscript, I would suggest that their conclusions are improper.

However, digging a little bit deeper, the journal that published this research, Molecules, is owned by the known pay-to-publish operation MDPI. Scientists and researchers have flagged MDPI as being a predatory operation and have questioned the quality of peer review in their journals. This may explain why this wasn’t flagged by reviewers prior to acceptance for publication.

So, have I convinced you yet that this publication doesn’t prove that artificial sweeteners aren’t toxic to your gut microbiome?

Good! Then I’m doing my job as a scientific communicator.

Headlines like the ones above erode public trust in science, which is a scary proposition. It’s no wonder that the average person can’t distinguish what is real and what is fake anymore— it’s hard enough for trained reporters in this environment. I don’t fault them— in many ways the science looks credible, and unless you have the background on the bench, you may not be able to differentiate what is real and what is not. But, I do want to put an offer out there:

Science can be difficult to decipher. Sometimes certain studies seem to contradict each other and other times results can come from less than credible sources.

The nuances of science deserve to be communicated and quality science should rise to the top. That is my job as a scientific communicator, and I’m happy to work with any reporter, at any time, to determine whether research findings (and their conclusions) are accurate.


This article was originally published on LinkedIn by Eric Moorhead, MS, Senior Scientific Executive. To learn more about fake science headlines and publications, check out our Ask A Scientist on Predatory Journals.