The Artificial Sweeteners Effect on the Gut Microbiome

By: Diana Orchant, Functional Medicine Registered Dietitian.
Clinically Reviewed by Michelle Miller, MSACN.

Let’s get nerdy!

Do you believe that stirring Splenda in your coffee is more beneficial than that pinch of sugar? Think again. Our society has been trained to demonize sugar but our taste buds still crave that something sweet. So, what do we do about that sweet tooth? Cue artificial sweeteners! Wondering whether or not they’re better for you than actual sugar? Spoiler alert… they’re not. However, while they may not result in a quick spike in blood glucose levels like regular sugar may, the effect on the body is more impactful and long-term. Let’s break it down…

Non-caloric artificial sweeteners (NAS) have been shown to wreak havoc on the gastrointestinal microbiome generally causing “dysbiosis” or an imbalance in the bacteria in our guts. Dysbiosis can result in gas, bloating, or have more serious impacts resulting in gastrointestinal diseases or widespread inflammation. Many types of artificial sweeteners have been demonstrated in research to cause an imbalance of the “bugs in our gut” (bacteria), including acesulfame potassium, aspartame (Equal), sucralose (Splenda), and saccharin (Sweet ‘N Low). There have been many complex studies on this topic, so we dove deeply into this for you. This topic is so heavily debated that we thought it’d be best if we stuck to the science.

A study conducted by Suez, J. et al. in 2015, tested the effect of saccharin, aspartame, sucralose, glucose, and sucrose on mice. There were 3 experimental groups where the mice received NAS poured into water, which included saccharin, sucralose, or aspartame. The controls used for this study were plain water, or water supplemented with glucose or sucrose (table sugar), making up 3 control groups. After 11 weeks, the control groups had comparable glucose tolerance curves, yet the 3 NAS experimental groups developed glucose intolerance, with saccharin having the strongest effect¹.

Next, these same mice were given heavy-duty antibiotics to wipe out the good bacteria in their guts. They were fed saccharin or slightly sweetened water. After a month of antibiotics and the consumption of saccharin vs. sweetened water, differences in glucose intolerance between NAS and control mice were undetectable¹. Translation: NAS causes glucose intolerance via alterations of the bugs in our gut. The NAS literally alter our gut’s good bacteria in a way that results in glucose intolerance, better known as more long-term sustained high blood glucose levels. Antibiotics wiped out the gut so there were minimal bacteria to alter at this stage in the process. Are you mind-blown? We are… but wait… there’s more!

Researchers then wanted to test the validity of the role of microbiota in glucose intolerance, just in case they were wrong. In the next study, fecal contents were transferred (AKA fecal transplants) from mice consuming saccharin or the control (glucose) into germ-free, new mice. Mice who received the fecal transplants from the saccharin-consuming mice had impaired glucose intolerance curves, whereas the mice who received fecal transplants from the control group did not¹.

Lastly, in case you still don’t believe the researchers, the fecal microbiota of the various groups was examined. The microbiota of the saccharin-consuming mice had a great deal of dysbiosis with more than 40 strains of bacteria having been significantly altered. Thus, the results of this multi-step study strongly linked NAS consumption with gut dysbiosis. So that artificial stuff really messes things up deep down and on many levels. We’re not joking around here!

Additionally, another NAS, Acesulfame Potassium (Ace-K), was given to male and female mice for 4 weeks, and it was shown that Ace-K disturbed the microbiome of mice, regardless of gender². So, if you think your husband or wife can get away with it they can’t—gender doesn’t matter! It is compelling that these little artificial sugars can dramatically alter our gut microbiomes in such a short period of time. While these studies were performed on mice, we must realize their limitations. Would you want to be a human in these studies? We certainly wouldn’t.

Now you must be wondering- so do I drink soda or diet soda? The answer is neither. While we know it’s not easy to cut these out, you can get plenty of sugar from natural sources such as fruits, or even some added sugars like honey or maple syrup. The key, however, is not too much and not too often. Having a sweet tooth can be a sign of gut imbalance and now you can officially blame your microbiome for that cookie (or three) that you had last night. It’s not you, it’s the bugs in your gut. Getting rid of your sweet tooth takes time, work, and often a bit of gut repair.

Experience top-notch care with PhysiologicNYC!

For more on this topic, check out our podcast, FUNC YOU UP! Ep 46: Sweet Little Lies. If you have further questions, we are here to provide answers. Reach out to us by phone, or fill out the form below to make an appointment.


  1. Suez, J., Korem, T., Zeevi, D., Zilberman-Schapira, G., Thaiss, C. A., Maza, O., . . . Elinav, E. (2014). Artificial
    sweeteners induce glucose intolerance by altering the gut microbiota. Retrieved From:
  2. Bian, X., Chi, L., Gao, B., Tu, P., Ru, H., & Lu, K. (2017). The artificial sweetener acesulfame potassium
    affects the gut microbiome and body weight gain in CD-1 mice. Retrieved From:

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