How Artificial Sweeteners Affect Gut Bacteria

You may be getting more than you bargained for when you reach for a diet soda. Research suggests that sucralose and other artificial sweeteners alter your gut bacteria and cause insulin resistance.

On April Fool’s Day, 1998, the Food and Drug Administration approved the artificial sweetener sucralose, aka 1,6-dichloro- 1,6-dideoxy-beta-D-fructofuranosyl-4- chloro-4-deoxy-alpha-D-galactopyranoside. But, despite its scary name, the worst it seemed to do was just be a rare migraine trigger in susceptible individuals, to which the manufacturer of sucralose replied that you have to weigh whatever risk there may be against its broader health benefits, “helping to mitigate the health risks associated with the national epidemic of obesity.”

As I discuss in my video Effect of Sucralose (Splenda) on the Microbiome, the hope was to offer a healthy sugar substitute to provide a sweet taste without the calories or spikes in blood sugar. However, that’s not how it appears to have turned out.

Population studies have tied consumption of artificial sweeteners, mainly in diet sodas, with increased risk of developing obesity, metabolic syndrome, and type 2 diabetes. But, an association is not causation. You’ve got to put it to the test.

Indeed, if you give obese individuals the amount of sucralose found in a can of diet soda, for example, they get a significantly higher blood sugar spike in response to a sugar challenge, requiring significantly more insulin—20 percent higher insulin levels in the blood—suggesting sucralose causes insulin resistance. This may help explain the links between artificial sweetener consumption and the development of diabetes, heart disease, and stroke.

So, sucralose is not some inert substance. It affects the blood sugar response. But how? The Splenda company emphasizes that sucralose is hardly even absorbed into the body and, as such, stays in the digestive tract to be quickly eliminated from the body. But the fact that it’s not absorbed in the small intestine means it makes it down to the large intestine and may affect our gut flora.

Studies have been done on artificial sweeteners and the gut bacteria of rats going back years, but there hadn’t been any human studies until fairly recently.

Researchers tested saccharin, sucralose, and aspartame, the artificial sweeteners in Sweet & Low, Splenda, and NutraSweet, respectively, and found that non-caloric artificial sweeteners induce glucose intolerance by altering the microbes in our gut.

The human studies were limited, but, after a few days on saccharin, for example, some people got exaggerated blood sugar responses tied to changes over just one week to the type of bacteria they had in their gut. Acesulfame K, another common artificial sweetener, also was found subsequently to be associated with changes in gut bacteria.

So, all this time, artificial sweeteners were meant to stave off chronic diseases but may actually be contributing to the problem due to microbial alterations. Some in the scientific community were surprised that “even minor concentrations of a sweetener [in this case, aspartame] are sufficient to cause substantial changes in gut inhabitants…” Others were less surprised.

Each molecule of aspartame is, after all, metabolized into formaldehyde. That may explain why some people who are allergic to formaldehyde have such bad reactions to the stuff. “Therefore, it is not unexpected that very small amounts of the sweetener can modify bacterial communities…”

However, the reports about the safety of aspartame are mixed. “All of the studies funded by the industry vouch for its safety, whereas 92% of independently funded studies report that aspartame can cause adverse health effects.” That should tell you something.

“Undoubtedly, consumers of these food additives, which are otherwise perceived as safe, are unaware that these substances may influence their gut bacteria. This may be of particular importance to patients with diseases correlated with modifications of the gut [bacteria], such as irritable bowel syndrome and inflammatory bowel diseases” (IBDs) like ulcerative colitis and Crohn’s disease. These individuals may not realize artificial sweeteners may be affecting their gut.

Might the effect be large enough to be actually see changes in the incidence of inflammatory bowel disease? Let’s look at Canada, the first country to approve the use of sucralose. Their rates of IBD did seem to double after the approval of sucralose. What about in the United States? After decades of relatively stable rates of ulcerative colitis and Crohn’s disease, rates did appear to start going up. In China, after the approval of sucralose, IBD rates rose 12-fold.

Again, these could just be total flukes, but such correlations were also found on two other continents as well. Indeed, the more graphs you see showing this rise in rates of IBD after sucralose’s approval in different countries, the harder it is to dismiss a possible connection.

The good news, though, is that after stopping artificial sweeteners, the original balance of gut bacteria may be restored within weeks.

Now, of course, the negative consequences of artificial sweeteners should not be interpreted to suggest that we should all go back to sugar and high fructose corn syrup. For optimal health, it is recommended that we all try to cut down on both. Can’t get enough of artificial sweeteners? Check out:

Erythritol May Be a Sweet Antioxidant, but there are some caveats for it and other nontoxic, low-calorie sweeteners. See:

Does it really matter if our gut flora get disrupted? You’re in for a surprise. See:

In health, Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations—2013: Uprooting the Leading Causes of Death and More Than an Apple a Day, 2014: From Table to Able: Combating Disabling Diseases with Food, 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet, and my latest, 2016: How Not to Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers. Related: Aspartame and the Brain Is There a Safe, Low-Calorie Sweetener? Aspartame: Fibromyalgia & Preterm Birth 

Related at Care2

Image via Thinkstock.

305 comments

Sarah Hill
Sarah Hill22 days ago

Artificial sweeteners will kill you! Don't use them!

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Sue M
Sue Magee1 months ago

Artificial sweeteners taste horrible!

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W. C
W. C1 months ago

Thanks.

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William C
William C1 months ago

Thank you.

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Biz M
Liza M1 months ago

Many thanks.

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Marge F
Marge F1 months ago

Thank you for posting this interesting article.

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Richard A
Richard A1 months ago

Thank you for this article.

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Julia S
Julia S1 months ago

Thank you!

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Renata B
Renata B2 months ago

Never, ever use them.

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Carol S
Carol S2 months ago

Thanks

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