Are sugar alcohols good or bad? Just the science

When someone asks me if sugar alcohols are healthy, I have to pause. It’s not a black and white issue. It depends on what you’re comparing them to.

If you’re comparing them to refined sugar, I’ll take sugar alcohols any day. They have fewer calories, a lower glycemic index, and aren’t trailing a barnyard of data linking them to chronic disease.

High-sugar diets make us sick. That much is clear.

But if you’re comparing sugar alcohols to, say, a low-carb sweetener like stevia, I’ll take stevia. Stevia has zero calories and—unlike sugar alcohols—rarely causes digestive upset.

It also depends on which sugar alcohol we’re talking about. Are we talking about xylitol, sorbitol, maltitol, mannitol, lactitol, or erythritol? Each has a distinct nutritional profile.

In this article, I’ll elucidate the pros and cons of sugar alcohols. Then you can decide if you want to use them.

Sugar Alcohols 101

Sugar alcohols (also called polyols) are sweet carbohydrates that are digested and metabolized differently than sugar. Instead of being digested through the small intestine and raising blood sugar, most sugar alcohols are digested by gut bacteria in the large intestine.

I say “most” sugar alcohols because erythritol doesn’t follow this pattern. This keto favorite passes through the small intestine and into the bloodstream, but unlike sucrose (table sugar), it’s not broken down. It’s excreted intact through urine.

By the way, sugar alcohols aren’t some weird chemicals concocted by mad scientists. They’re found naturally in grapes and mushrooms, and when they’re synthesized, they’re synthesized from natural forms of sugar.

Sugar alcohols are used to sweeten medicines, gum, and low-carb processed snacks and sweets. With more and more people going keto, they’re becoming increasingly popular sugar substitutes.

One last thing. Despite the name, there is ZERO ethanol (what we consider alcohol) in sugar alcohols. Somewhere, somebody out there is trying to get buzzed off xylitol gum. But that person isn’t the type of person (like you) who reads evidence-based blogs on sugar alcohols.

4 Common Sugar Alcohols

Here I’ll give a brief rundown of the four most common sugar alcohols. Each has different nutritional profiles and effects on the body.

#1: Maltitol

Derived from maltose (a type of sugar), maltitol is said to mimic sucrose rather nicely. It’s about 90% as sweet and contains nearly half the calories.

But maltitol has a glycemic index of 35—more than half that of sucrose at 65. This means that ingesting maltitol will significantly raise blood sugar for most people. (Note: the glycemic index measures how rapidly a food raises blood sugar on average).

In other words, maltitol isn’t a keto-friendly sweetener. Unlike other sugar alcohols, grams of maltitol should count towards your keto carb limit.

#2: Sorbitol

Sorbitol was once the preferred sugar alcohol for sweetening sugar-free treats. It’s 50-70% as sweet as sugar, contains 2.7 calories per gram, and has a favorable glycemic index of 9.

Why has sorbitol gone out of favor? Because even in small quantities, sorbitol can cause gas, bloating, and other GI issues.

#3: Xylitol

The most researched of the sugar alcohols, xylitol is ubiquitous in gum, medicine, and processed foods. It’s just as sweet as sugar but only has a glycemic index of 13.

Xylitol is better tolerated than sorbitol, but it still causes digestive upset in many folks.

#4: Erythritol

Erythritol tends to cause fewer GI issues than the other sugar alcohols. Why? Because most of it never reaches the large bowel to be fermented by gas-producing bacteria.

Rather, it’s absorbed intact through the small intestine and excreted intact through urine. In and out.

Other strong points of erythritol include its glycemic index (0), its low-calorie count (0.2 per gram), and its dental benefits. Erythritol is in a class of its own. Beyond xylitol in oral care products, it’s the only sugar alcohol I actually recommend.

Sugar Alcohols: The Good

Sugar alcohols trump sugar on calories, blood sugar effects, dental health, and a few other areas. Let’s cover those now.

Calories

All sugar alcohols are significantly less caloric than sugar. Sucrose has 3.9 calories per gram, while most sugar alcohols have about half that amount. And erythritol (oh erythritol!) has close to zero calories.

Do calories really matter that much? Yes. I believe the bulk of sugar’s evils can be explained by overeating.

Sugar is easy to overeat. It doesn’t fill you up. A person could drink soda all day and not feel full. (Millions do). And soda contains a TON of empty calories. Is it any surprise that we have an obesity crisis?

By sweetening with fewer calories, sugar alcohols can help folks reduce their intake of empty calories. And overeating sugar alcohols isn’t really an issue, due to the potential for GI distress.

Blood sugar impact

If you want to live a long and healthy life, it’s wise to minimize the frequency and magnitude of your blood sugar spikes.

High blood sugar causes all sorts of problems. It stokes inflammation, messes with longevity genes, shuts down fat burning, prevents ketogenesis, drives insulin resistance, the list goes on.

How can you keep blood sugar within healthy ranges? Avoiding added sugars like sucrose and high fructose corn syrup is a good place to start.

And if you want to replace sugar, replace it with low-glycemic sweeteners like stevia, monk fruit, allulose, and—yes—sugar alcohols.

Except for maltitol, most sugar alcohols have a mere fraction of sugar’s glycemic impact. Erythritol is the best of the lot with a GI of 0.

#3: Oral health

Xylitol is well-documented to help prevent cavities. It does so by suppressing the growth of an oral bacteria called Streptococcus mutans that causes plaque to accrue on teeth.

That’s why you see xylitol in gum, toothpaste, and mouthwash. It’s good for your choppers.

There’s also research showing that erythritol squashes plaque. (Even better than xylitol). But since erythritol costs more to produce, it probably won’t replace xylitol anytime soon.

Other benefits

Here are examples of other health benefits linked to sugar alcohols:

  • Erythritol has potent antioxidant effects and has been shown to improve blood vessel function in a pilot study of type 2 diabetics.
  • Xylitol was found to enhance the intestinal microbiome in mice, which “may exert a favorable effect on bone health”.
  • Rats fed xylitol showed improved bone mineral density.
  • In a separate study, rats fed xylitol showed increased skin collagen content.

Sugar Alcohols: The Bad

Any reason to worry about sugar alcohols? Beyond the glycemic impact of maltitol (which we already covered), here are the main drawbacks:

Digestive issues

The biggest downside of sugar alcohols is that they cause gas, bloating, diarrhea, and other forms of GI distress. This happens because sugar alcohols are fermented by gut bacteria, and fermentation creates gas as a byproduct.

Heard of FODMAPs? Polyols (aka, sugar alcohols) are the “P” in that group of fermentable carbohydrates. And low-FODMAP diets that restrict sugar alcohols appear to be effective at reducing the symptoms of irritable bowel syndrome.

But even for those without IBS, sugar alcohols can be problematic. Sorbitol is probably the worst offender, which is why it’s becoming increasingly rare.

Xylitol is better tolerated, but people still start to experience nausea, watery feces, bloating, and diarrhea at intakes of 35 to 50 grams. In contrast, 35 grams of erythritol was well-tolerated, though 50 grams caused stomach gurgling and nausea in some healthy people.

Not dog-friendly

If you have a dog, keep the xylitol away from them. It’s safe for humans, but not for pups.

When dogs ingest xylitol, it triggers (researchers believe) a massive release of insulin, the blood-sugar regulation hormone. This insulin dump causes blood sugar levels to plummet. The resulting hypoglycemia can lead to liver failure, among other complications.

On the bright side, hypoglycemic dogs generally recover well with appropriate veterinary care. But best not to find out.

Are Sugar Alcohols Healthy?

Compared to sugar, sugar alcohols are model citizens of the sweetener community. They’re sweet enough to do the job, low-glycemic, and—most importantly—not linked to every stinkin’ disease in the book.

But they’re not perfect. Even in healthy folks, they often cause GI distress. And folks that have existing gut issues should probably avoid them entirely.

The exception is erythritol, which largely skips colonic fermentation. Erythritol also has the lowest glycemic index and caloric load. Because of this, erythritol makes my shortlist of keto-friendly sweeteners—but it doesn’t sit in my top 3.

That spot is reserved for stevia, monk fruit, and allulose. Read my blog, the pros and cons of 12 popular sugar substitutes, to learn why the science leads me to favor these options.

But again, the big win is cutting back on sugar. Do that and you’ve won most of the battle.