Artificial sweeteners: bad for your gut?

With artificial sweeteners working their way into products on nearly every aisle of the grocery store, it's becoming increasingly relevant to better understand how they can affect your gut physiology. Are artificial sweeteners bad for your gut? Do artificial sweeteners affect your microbiome? Can artificial sweeteners give you GI problems? While the data is controversial, there's increasing evidence that artificial sweeteners may not be as harmless as once thought.


What are artificial sweeteners?

It's estimated that every day, 11% of healthy-weight, 19% of overweight, and 22% of obese adults drink diet beverages, but what exactly makes these sugar-free drinks sweet? The four most popular low calorie sweeteners are sucralosesaccharin, acesulfame-potassium and aspartame. Although all four share the characteristic of adding sweetness without calories, they are all quite different in their chemical composition and in turn, how your body processes them varies widely. As an example, sucralose is mostly not digested at all, with about 75% of it excreted in your poop. In contrast, aspartame and acesulfame-potassium is absorbed in your small intestine, and is excreted through your urine. These products have become so commonplace, that one study showed 65% of women had byproducts of these sweeteners in their breast milk. While these products have been deemed safe by regulatory agencies such as the FDA, differentiating what foods are "healthy" is not truly within the purview of regulatory agencies, and better understanding how these products influence gut health is an active area of research. Multiple studies have shown that despite sweeteners not containing calories, people who regularly eat or drink them may have a higher risk of obesity, diabetes, and high blood pressure even when controlling for weight gain.


Do artificial sweeteners alter the gut microbiome?

Disruptions in the microbiome have been associated with trends towards obesitydiabetes, and cardiovascular disease.  Animal studies dating back to the 1980's have shown that sugar substitutes affect gut bacteria, however our evolving understanding of the gut microbiome has led to a wealth of recent papers studying how artificial sweeteners affect the gut. From reduction in bacteria counts to changes in how carbohydrates were absorbed, artificial sweeteners may play a much larger role in gut health than previously thought. Sucralose, aspartame, and saccharin have all been shown to disrupt the balance and diversity of gut microbiota. 

A recent study published in Nature demonstrated that artificial sweeteners can contribute to glucose intolerance - a precursor for diabetes - through changes to the gut microbiome. The study looked at long-term sweetener consumption in healthy people, and showed an association between artificial sweetener intake and negative changes to body type including increased waist-to-hip ratio due to excess body fat around the waist. In animal studies, artificial sweeteners were associated with both bowel and liver inflammation. The take home point is simple: artificial sweeteners are not without harm.


Artificial sweeteners and irritable bowel syndrome

The medical community's understanding of what contributed to irritable bowel syndrome is still evolving, however what you eat clearly impacts how your gut functions. If you've read our article on the FODMAP diet, it shouldn't be a huge surprise that artificial sweeteners may be contributing to your GI symptoms.

Polyols such as mannitol, sorbitol, and xylitol are a common type of sugar-free sweetener. The "P" in FODMAP, patients with irritable bowel syndrome may benefit from avoiding polyols, particularly if other high-FODMAP foods give them GI symptoms such as diarrhea, flatulence, bloating, or cramps. Even without IBS, it is difficult for many people to digest these complex carbohydrates, and reading product labels may clue you in to which sweeteners may be giving you symptoms.

While sucraloseacesulfame-potassium, saccharin, and aspartame are technically not high in FODMAPs, this doesn't make them immune from causing GI symptoms. Some patients with IBS have significant alterations in their gut microbiota, and artificial sweeteners may be contributing to your symptoms in more ways than one.


My approach? In general, I avoid processed foods and artificial sweeteners, but having an overly restrictive diet can be harmful as well. Learning how the gut works, and being mindful of your dietary habits is a good first step. The medical community still has a lot to learn about artificial sweeteners and I welcome any questions or comments you have on the topic through the Q&A section of our website.

-The Gut Doc


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