Artificial Sweeteners

Over the last two weeks I've pushed back on exaggerated headlines about erythritol, Splenda, and aspartame. You might think that means I believe artificial sweeteners are perfectly safe and everyone should use them freely.

That's not what I'm saying. There are real, documented concerns anyone using these products should understand. They're just not the ones the headlines focused on.

How Sweeteners May Work Against Your Habits

The mouth and digestive tract contain receptors that can detect sweet taste. When you eat or drink something sweet, the body may begin preparing for incoming calories before they even arrive. That preparation can include shifts in appetite signals and gut hormones. Researchers refer to this anticipatory response as the cephalic phase response, though not every sweetener-related craving effect falls neatly under that label.

The concern with zero-calorie sweeteners is strongest when intense sweetness arrives with few or no calories, or without the normal food structure that usually accompanies sweet foods. Some research suggests that mismatch may increase hunger or cravings later. The effect isn't universal and doesn't show up consistently across all studies or all sweeteners. But it's a plausible enough mechanism that it helps explain why some people find that diet drinks don't help them eat less overall.

This concern isn't limited to aspartame or sucralose. It may apply to sweet taste in general, including stevia-based products, though the effect appears to vary by person, product, and context.

Sugar Alcohols Are a Different Story

Sugar alcohols like xylitol, sorbitol, and mannitol get grouped with artificial sweeteners, but they work differently and come with their own specific issues.

Their calorie content varies. Some provide roughly half the calories of regular sugar. Erythritol provides very little usable energy, which is why it's become so popular in low-calorie products.

People with diabetes should know that some sugar alcohols, especially maltitol, can still affect blood glucose in meaningful ways. Others, like erythritol, have very little effect on blood sugar. Reading labels carefully and knowing which sugar alcohol is in a product matters more than treating them as a single category.

Sugar alcohols also don't feed the bacteria in your mouth that cause tooth decay, which is why they show up in sugar-free gum and dental products.

The concern most people don't know about is what happens in the digestive system. Sugar alcohols are poorly absorbed in the small intestine, so they travel to the large intestine where gut bacteria ferment them. That fermentation produces gas, bloating, cramping, and in larger amounts a significant laxative effect. In some cases the cramping and diarrhea can be severe enough that people seek medical care. If you've had that experience after eating sugar-free candy, chocolate, or baked goods, check the label for mannitol or sorbitol. Those two are the most likely culprits.

Erythritol is somewhat different. Much of it is absorbed in the small intestine and excreted in urine, so it's generally less likely to cause the gas and laxative effects you'd get from sorbitol or mannitol, though large amounts can still bother some people. As covered in Part 1, the fact that erythritol circulates in the blood is also why the cardiovascular research around it, particularly the experimental work linking it to platelet activation, is worth watching even though causation at normal intake levels hasn't been established.

A Note on Phenylketonuria

As mentioned in Part 2, people with the genetic condition phenylketonuria, or PKU, need to avoid aspartame specifically because it contains phenylalanine, which people with PKU can't process safely. Products with aspartame are required by law to carry a warning about this. For people without PKU, phenylalanine from aspartame is not considered a concern at normal intake levels.

The Microbiome Question

Your gut microbiome is the community of trillions of bacteria, viruses, and other microorganisms living in your digestive tract. Research has established that this community plays an important role in metabolism, immune function, and overall health.

Several studies have linked certain sweeteners, particularly saccharin and sucralose, to changes in gut bacterial diversity and some measures of metabolic function. The proposed mechanisms include reduced production of beneficial compounds called short-chain fatty acids and activation of inflammatory pathways. These findings are real enough to take seriously, but how much they matter at normal consumption levels in healthy people is still being worked out.

Stevia may have a more favorable profile in some short-term studies, but long-term evidence is still limited, and stevia products aren't all formulated the same way. It's too early to declare any sweetener the clear winner in this area.

The Bigger Picture

For most approved non-sugar sweeteners, the strongest concern is probably not proven cancer risk or clearly established cardiovascular harm at normal intake levels. The more practical concern is behavioral.

Sweeteners work best as a temporary bridge. If someone is drinking several regular sodas a day and switches to diet versions as part of a genuine effort to change their eating habits, that's a reasonable strategy. The controlled trial evidence supports modest short-to-medium-term benefits in that situation.

Where sweeteners tend to fall short is as a permanent solution. They can keep the expectation of intense sweetness in place without ever reducing it. Research suggests that sweetness perception isn't fixed. In one study, people who reduced their sugar intake over several months rated moderately sweet foods as tasting sweeter than before. They didn't necessarily stop liking sweet foods, but their threshold shifted. With repeated exposure to less-sweet foods, some people find that intensely sweet products become less necessary or less appealing over time.

That shift is worth more than any sweetener swap. The goal that serves long-term health best isn't finding the perfect substitute for sugar. It's gradually building a diet that doesn't need everything to taste like dessert.

Do you want to live a healthier life? Eating a varied diet rich in fruits, vegetables, whole grains, and fiber is essential. Additionally, avoiding excessive use of antibiotics unless necessary and managing stress levels can help promote a healthy gut microbiome.

Start tracking your calories. Write down everything you eat and drink over a day and see how much you take in. Most people are shocked when they realize just how high that number is.

Lift weights at least two or three times a week. Do cardio workouts at least two or three days a week. Get to bed and sleep more. Doing all that can make fundamental, meaningful changes to your health and longevity.

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7/2/2023
Updated 5/26/2026