Researchers estimate that about 75% of all processed foods include a commercially used sweetener, which includes artificial and natural sweeteners, as well as sugar alcohols.
Past studies have linked consuming artificial sweeteners to several potential health issues, including a higher risk of heart disease, stroke, type 2 diabetes, metabolic syndrome, cognitive decline, chronic kidney disease, and cancer.
Previous research has also shown a potential negative impact of consuming artificial sweeteners on the gut microbiome.
Now, a new study published in the journal Molecular Systems Biology reports that certain commercially used sweeteners — including artificial sweeteners — slow or stop the growth of beneficial gut bacteria, either on their own or through enhanced effects when combined with certain compounds and drugs.
For this study, researchers used an in vitro model in which 25 different gut bacterial species were grown in a lab. These bacterial species included those that are helpful to the gut, those that are harmful, and those that stay neutral.
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Each bacterial species was then exposed to 39 common, commercially used sweeteners. The sweeteners included:
“Sweeteners are widely used as sugar substitutes in various food and beverages,” Kiran Raosaheb Patil, PhD, professor of molecular systems biology in the MRC Toxicology Unit at the University of Cambridge, and co-lead author of this study, explained to Medical News Today.
“Previous studies and World Health Organization (WHO) guidance have shown links between sweeteners and health parameters. It is therefore important to investigate molecular mechanisms through which the sweeteners may be affecting physiological processes. Such molecular insights can guide better-informed decisions for sweetener usage.”
At the study’s conclusion, researchers found that of the 39 commercially used sweeteners tested, about 75% altered the growth of at least one gut bacterial species.
“We tested sweeteners and related compounds to assess which, if any, can impact gut bacterial growth,” Patil said.
“Our laboratory tests show that many sweetener compounds have the potential to alter the growth of certain gut bacteria. While we yet do not know how these results would translate in a human context, our results suggest that future cohort studies should consider the direct effect on growth and metabolism of gut bacteria,” he explained.
Scientists also tested each sweetener in combination with common food compounds such as caffeine and vanillin (vanilla extract), as well as eight commonly used drugs to see how those combinations might impact gut bacteria.
Researchers observed more than 100 interactions between the combinations. The most eye-catching, researchers say, was the combination of isosteviol — a compound derived from stevia —and the antidepressant duloxetine. This combo suppressed two gut bacteria that play important roles in maintaining a healthy digestive system.
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“Isosteviol is a sweetener derivative and not a sweetener itself; it was included in the study to broaden the mechanistic scope from a chemical angle,” Patil explained. “Our study included Stevioside and Rebaudioside A, both stevia sweeteners, and Rubusoside, another steviol glycoside found in Chinese sweet tea.”
“Like isosteviol, these compounds showed synergistic interactions with duloxetine. Our data highlights that sweeteners may interact with medications, and such ‘mixture effects’ should be investigated in future clinical studies. These effects may not necessarily be harmful, but for now we simply do not know.”
— Kiran Raosaheb Patil, PhD
MNT spoke with Ashkan Farhadi, MD, a board certified gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, about this study.
Farhadi, who was not involved in this research, commented that this is one of the most comprehensive studies on the effects of sweeteners, including artificial sweeteners, on the gut microbiome.
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“[The study] not only looked into the effects of that directly on the microbiome; it’s looking into the effects on other food ingredients and materials, and their combination of their effects. So it’s very interesting in that respect. And what it does for me is confirm that the reaction of the bacteria and the work they do can be affected by many things we are doing, including artificial sweeteners.”
— Ashkan Farhadi, MD
“This study is an in vitro study on bacterial culture, and we need to have similar studies in an animal model or, even better, in humans to see if artificial sweeteners can adversely affect the growth or proliferation of good germs in the human gut, so we have more direct evidence to provide recommendations,” Farhadi added.
For readers who may want to start reducing the amount of commercially used sweeteners they consume, MNT asked Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight — who was likewise not involved in this study — for her top tips.
“Rather than completely eliminating every questionable ingredient ‘cold-turkey,’ I encourage clients to gradually retrain their palate while building their knowledge base. Small, simple changes are often the most beneficial and sustainable long-term.”
— Monique Richard, MS, RDN, LDN
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“Often navigating these changes doesn’t require anything fancy or expensive, but is about identifying what you like, what you’re currently consuming — by reading, investigating, and observing daily intake through labels, ingredient lists, and logging — and exploring how that can be modified,” she detailed.
Richard said some simple strategies may include:
“One concept I often emphasize with clients is that the goal isn’t simply ‘less sugar,’ or elimination of ‘ultra-processed foods,’ but about increasing the plethora of plants that Mother Nature provides,” she explained. “As whole foods begin replacing ultra-processed options, sweetener intake often decreases naturally,”
“It is also not about villainizing or creating a righteous ‘clean eating’ judgment zone for you/your children/family/friends when looking at products,” Richard added. “It is about being informed, the broader dietary pattern and overall quality, adequacy, and enjoyment of fueling our life.”
