Stevia, Erythritol and the Gut Microbiome

The push toward artificial sweeteners has a reasonable premise. Sugar damages health. Blood sugar spikes cause disease. So let's use something sweet that doesn't spike blood sugar. The logic is sound. The execution is broken.

Stevia and erythritol are marketed as the answer. They're not chemicals, the marketing says. They're natural plant extracts. Your body won't even absorb them, so they're safe. The promises are comforting. The reality is more complex.

Natural does not mean your body recognises it

Stevia comes from a plant. That's true. Erythritol is made by fermenting glucose with fungi. That's also technically true. Neither is synthetic. Both are natural in the strictest sense.

But your body doesn't care whether something is natural. Your body cares whether it recognises something as food. And your body does not recognise stevia or erythritol as food.

Stevia is a glycoside compound that tastes sweet but isn't sugar. Your taste buds signal sweetness. Your digestive system doesn't know what to do with it. It's not being used for energy. It's not being metabolised normally. It's being treated as something foreign.

Erythritol is a sugar alcohol. Your small intestine doesn't absorb it well. So it passes into your large intestine undigested. Your colon has to deal with it. And your gut bacteria have to deal with it.

The fact that something is natural doesn't make it good for you. Arsenic is natural. Ricin is natural. Hemlock is natural. Nature is full of compounds that are toxic or indigestible to humans. The question is not whether something is natural. The question is whether your body recognises it as food.

Just because your body doesn't absorb stevia or erythritol doesn't mean they're safe. It means your body rejects them as foreign.

What sweeteners do to your microbiome

Your gut bacteria are part of your immune system. They produce neurotransmitters that affect mood and cognition. They produce short-chain fatty acids that support gut health. They protect against pathogens. They're not just residents in your gut. They're partners in your health.

Stevia and erythritol are not food for your gut bacteria. Your beneficial bacteria evolved eating the foods your ancestors ate: fibre, resistant starch, fermented foods, whole plants. They didn't evolve eating stevia or erythritol.

When sweeteners enter your colon undigested, your bacteria have to process them. Some bacteria thrive on the sweetener. These are often not the beneficial species. The opportunistic bacteria, the ones you don't want thriving, may actually prefer erythritol.

Research shows that erythritol can increase populations of undesirable bacteria whilst decreasing beneficial species.¹ It's a selective pressure that favours dysbiosis. Your microbiome becomes less resilient. Pathogenic bacteria have more room to proliferate.

Stevia has been shown to alter the composition of the microbiome in ways that reduce beneficial bacteria.² The mechanism isn't fully understood, but the effect is clear. Stevia changes the population of your gut bacteria in ways that are less healthy.

Over time, chronic dysbiosis leads to intestinal permeability, immune dysregulation, and metabolic dysfunction. The sweetener is cheap, calorie-free, and harmless in the moment. But it's damaging to the infrastructure that keeps you healthy.

Stevia and erythritol are not metabolised as food. They're processed as foreign compounds. Your microbiome pays the price.

The insulin response you don't see

The marketing for these sweeteners emphasises that they don't spike blood sugar. That's true. But it doesn't mean they don't affect insulin.

Insulin response is not entirely dependent on blood glucose. Your gut bacteria produce compounds that signal insulin secretion. Your taste buds trigger insulin responses. Your digestive tract anticipates what's coming and preps insulin in advance.

When you consume something that tastes sweet but isn't providing calories, your body is confused. It releases insulin in anticipation of sugar. The sugar never arrives. Now you have insulin without glucose. Your blood sugar actually drops. You feel hungry. You crave more food.

This creates a metabolic dysfunction. Your insulin response is trained to trigger at the taste of sweetness, even when no calories arrive. This is exactly the opposite of what you want. You want your insulin to respond to actual nutrition, not to phantom sweetness.

Chronic consumption of sweeteners without calories actually increases insulin resistance.⁴ Your body becomes less sensitive to insulin signalling because the signal (sweetness) is not matched by the normal nutritional consequence (calories and nutrients).

Some research suggests that sweeteners may actually cause weight gain because of this mechanism.³ You're triggering hunger without providing satiety. You end up eating more.

Sweeteners don't spike blood sugar, but they confuse your insulin system and trigger hunger. That's not a win.

Why whole foods are better

If you need sweetness, use honey, maple syrup, or fruit. These are foods. Your body recognises them.⁵ Your digestive system knows what to do with them.

Honey contains trace minerals. Maple syrup contains polyphenols and antioxidants. Fruit contains fibre and vitamins alongside the carbohydrate. You're getting nutrition, not just sweetness.

Yes, these spike blood sugar. They contain real carbohydrates that your body metabolises normally. Your pancreas responds. Your blood sugar rises and then falls. The system works as evolved.

The question is not whether you spike blood sugar. All carbohydrates spike blood sugar. The question is whether the carbohydrate comes with cofactors, nutrients, and fibre that support your body's ability to process it.

Whole-food sweeteners come with their own support system. Honey comes with enzymes. Maple syrup comes with polyphenols. Fruit comes with fibre and vitamins. Your body processes these completely differently than isolated sweetness.

The dose matters, obviously. Eating honey constantly is not better than eating sweeteners constantly. But occasional honey, maple syrup, or fruit is infinitely better than chronic sweetener consumption.

Your body evolved eating honey and fruit, not stevia and erythritol. Feed it what it evolved eating.

The taste receptor confusion

Your taste receptors evolved to identify nutrients. Sweetness signals carbohydrates. Umami signals protein. Saltiness signals minerals. Your taste system is information gathering.

When you consume something that tastes sweet but provides no carbohydrates, you're lying to your taste system. You're training your taste receptors to mistrust sweetness. Over time, this creates a confused signal.

People who use stevia or erythritol chronically often report that foods taste different. Natural sweetness becomes less satisfying. Fruit tastes bland. Honey tastes cloying. The taste receptors have been recalibrated to expect the intense sweetness of artificial compounds.

This is a form of taste dysregulation. It's similar to what happens with processed foods. The more processed foods you eat, the less satisfying whole foods become. You need more and more stimulation to feel satisfied.

Using sweeteners teaches your body to crave sweetness without providing the nutrition that sweetness normally signals. You end up craving sweets more, not less.

The bottom line

This pillar avoids stevia and erythritol not because they're toxic in the short term. They're not. They're avoided because they disrupt the microbiome, confuse insulin signalling, and dysregulate taste receptors. They're anti-nutrient in the strictest sense.

If you're using them to avoid sugar, stop. Use less honey or maple syrup instead. Your body recognises these as food. Your bacteria can process them. Your insulin system understands them.

If you need sweetness, eat whole fruit. It comes with fibre, vitamins, and minerals. Your body processes it completely. There is no clean sweetener that's sweeter than food and better for you than food.

The body is not asking for perfect optimisation. It's asking for recognition. Feed it whole foods. Everything else is pretending to be something it's not.

References

1. 1. Witkowski M, Nemet I, Alamri H, et al. The artificial sweetener erythritol and cardiovascular event risk. Nature Medicine. 2023;29(3):710-718. https://pubmed.ncbi.nlm.nih.gov/36849732/
2. 2. Suez J, Korem T, Zeevi D, et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014;514(7521):181-186. https://pubmed.ncbi.nlm.nih.gov/25231862/
3. 3. Pearlman M, Obert J, Casey L. The association between artificial sweeteners and obesity. Current Gastroenterology Reports. 2017;19(12):64. https://pubmed.ncbi.nlm.nih.gov/29159583/
4. 4. Suez J, Cohen Y, Valdes-Mas R, et al. Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance. Cell. 2022;185(18):3307-3328. https://pubmed.ncbi.nlm.nih.gov/35987213/
5. 5. Bogdanov S, Jurendic T, Sieber R, Gallmann P. Honey for nutrition and health: a review. Journal of the American College of Nutrition. 2008;27(6):677-689. https://pubmed.ncbi.nlm.nih.gov/19155427/