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Gut Health

Sugar Substitutes Might Alter How the Microbiome Works

Swapping sugar for a no-calorie alternative may not be great for your gut.

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One of the most popular ways packaged products cut out the sugar and keep the sweetness is by subbing in sugar substitutes or sweeteners. Plenty of these sweetening agents sound great – zero calories, none of the drawbacks of refined white sugar, no harm. But research now suggests that switching sugar with a stand-in substitute may actually have a not-so-great effect on your body’s microbiome.

Sugar substitutes have more of an impact on the body than previously thought

Sugar substitutes, which are also called non-nutritive sweeteners, have long been thought of as an improvement over sugar. That’s primarily because it was believed that these sweeteners had no impact on the body when consumed. As the Mayo Clinic notes, there are plenty of potential benefits to using sweeteners, too, such as better weight control, fewer carbohydrates, and less concern about tooth decay and cavities.

However, a study published in Cell in August 2022 found that non-nutritive sweeteners may not be as worry-free as originally thought. These sweetening agents may affect blood sugar levels more noticeably – and they may also shape how the microbiome works.

The study’s researchers began their work in 2014, when the team discovered that non-nutritive sweeteners affected the microbiomes of mice, altering their glycemic responses. They then took their work from animal models to humans, screening over 1,300 individuals to find people who avoid non-nutritive sweeteners in their daily diets. After narrowing the group down to 120 participants, the researchers divided them into six groups: two control groups and four groups who began consuming daily amounts of either aspartame, saccharin, stevia, or sucralose in amounts below the FDA’s daily allowance.

At the study’s end, researchers saw distinct changes in the microbiomes of those who consumed the non-nutritive sweeteners. Every one of the non-nutritive sweetener groups saw glycemic changes. Two particular sweeteners, saccharin and sucralose, had a significant impact on the participants’ glucose tolerance. 

And when researchers took a look at what was causing those altered glycemic responses, it was the gut. Non-nutritive sweeteners appeared to change the behavior of gut microbes; the sweeteners caused the microbes to change how the participants’ bodies handled glucose. 

What, exactly, are non-nutritive sweeteners?

If you’re wondering whether the sweeteners you turn to fall into the category of non-nutritive sweeteners, it’s likely that they do. According to the Cleveland Clinic, any substances used in place of sugar – like sucrose, agave nectar, honey, or corn syrup – to sweeten items are defined as non-nutritive sweeteners.

Typically, these sweetening agents also have few to no calories or nutrients. They can be derived from pretty much anything, including sugar itself, and they tend to be more intensely sweet than sugar alone. 

Additionally, there are a few non-nutritive sweeteners that are FDA approved: 

  • Aspartame
  • Acesulfame potassium
  • Monk fruit extract
  • Neotame
  • Saccharin
  • Stevia
  • Sucralose
  • Advantame

What does this mean for those who consume sweeteners?

It’s important to note that the researchers didn’t draw any firm conclusions about how non-nutritive sweeteners may negatively – or positively – impact the microbiome, the gut and its microbes, or even long- and short-term glycemic response. 

The researchers did point out that the effect of non-nutritive sweeteners will likely vary from individual to individual, as everyone’s microbiome is unique. And the biggest takeaway from their work should be that these sweeteners may not be as innocuous as once thought. Instead, anyone who’s subbing in these alternatives to sugar should be aware that they can have their own, different impact on nutrition. 

Ultimately, more research is needed to fully understand what kind of impact they may have, and whether or not they’re worthy of any concern. 

So, should you be worried about sugar substitutes?

I asked Elizabeth Shaw, MS, RDN, CPT, and founder of Shaw Simple Swaps, whether this study should be cause for concern regarding the use of non-nutritive sweeteners like monk fruit and agave nectar. “I’ve said this for a long time, that too much of a good thing is never a good thing! This includes the non-nutritive sweeteners that are ‘free from’ everything, but still elicit that sugary taste many have come to use on a regular basis,” Shaw explains. “This recent study shows as with everything, research evolves, and with these new findings the impact these non-nutritive sweeteners have on individual microbiome is unique for everyone.”

So, should you start limiting your use and intake of non-nutritive sweeteners, even if you’re opting for the more natural sweeteners available? “While I am not saying that you need to avoid non-nutritive sweeteners all together based on this study, I would advise individuals to take a close look at their own dietary habits and how often they are consuming ingredients like these,” Shaw says. 

There’s no reason to fear non-nutritive sweeteners – or even sugar. As Shaw explains, “Working on balance, not deprivation is key. Rather than fear sugar in its natural form (hello, cane sugar is from a plant, too), work on using less of the real stuff and incorporating more of the natural sources of sugars from fruits like bananas, dates, [and] prunes!” 

In need of some inspiration? Try these recipes that feature natural sugar sources instead of sugar substitutes: