Erythritol, Maltitol, Xylitol: What Are Sugar Alcohols and Should You Avoid Them?

Pick up almost any protein bar that says "low sugar" or "no added sugar" on the front, flip it over, and read the actual ingredients list. There's a good chance you'll find one of these: maltitol, erythritol, xylitol, sorbitol. They're called sugar alcohols, and they're the reason a bar can taste sweet while claiming barely any sugar.

Here's the part most people miss. Sugar alcohols don't show up in the sugars line on the nutrition panel, and under Australian labelling rules they don't count as added sugar either. So a bar can be loaded with them and still display the claims that made you pick it up. The only place they appear is the ingredients list.

This article explains what they actually are, how they differ from each other, and what the current research says about each one. Some are better tolerated than others. A couple have picked up genuine cardiovascular question marks in the last two years. I'll tell you which is which, cite the actual studies, and be honest where the science isn't settled. By the end you'll be able to read any bar's label and decide for yourself.

What sugar alcohols actually are

Sugar alcohols are a class of carbohydrate called polyols. The name is misleading on both counts: they're not alcohol in the sense that gets you drunk, and they're not quite sugar either. Chemically they sit somewhere in between, a sugar molecule with a structure that's been altered enough to change how your body handles it.

Most of the ones in your food are made industrially, usually by hydrogenating sugars derived from corn or wheat starch. A few of them, erythritol and sorbitol among them, do occur naturally in small amounts in fruits and vegetables. But the quantities used to sweeten a protein bar are nothing like what you'd ever get from eating fruit. The 2024 Cleveland Clinic research measured this directly: a single 30g dose of erythritol raised blood levels more than a thousandfold above what the body normally carries. So "it's found in nature" is technically true and practically meaningless when it comes to the doses in processed food.

On an Australian label they show up either by their name (maltitol, erythritol, xylitol, sorbitol, isomalt) or by an E number in the 900s or, in sorbitol's case, 420. Once you know the names, they're easy to spot. The harder part is knowing what each one does, which is the rest of this article.

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Why they're in your protein bar

Sugar alcohols solve several problems for a bar manufacturer at once, which is why they're so common.

The first is sweetness at a lower calorie cost. Most polyols carry roughly half the calories of sugar, around 2 to 2.6 calories per gram against sugar's 4, because the body can't fully absorb or metabolise them. That lets a bar taste sweet while the calorie count stays down.

The second is texture. Sugar alcohols hold moisture and give a bar that soft, fudgey, slightly chewy bite. Anyone who's eaten a date-and-nut bar next to a typical protein bar knows the difference in mouthfeel, and polyols are part of how the second one gets there without much in the way of real food doing the work.

The third is blood glucose. Most sugar alcohols raise blood sugar less than regular sugar does, which is what lets a product position itself as low-GI or diabetic-friendly. How much less depends entirely on which one, and as you'll see, maltitol is far less innocent here than the marketing suggests.

The fourth is the one that matters most commercially: the label. Because sugar alcohols don't count as sugar on an Australian nutrition panel, they let a bar carry "no added sugar" or "low sugar" on the front while still tasting like dessert. That single labelling quirk is doing more selling than any of the other three reasons combined.

The sugar alcohols worth knowing

Not all polyols behave the same way. The differences between them, how much they spike your blood sugar, how badly they upset your gut, and what the latest research says about them, are large enough that lumping them together as "sugar alcohols" hides the important stuff. Here are the five you're most likely to meet on an Australian label, roughly in order of how much they should concern you.

Maltitol (E965)

Maltitol is the one you'll run into most often, especially in the chocolate coating of protein bars, where it does the sweetening the front of pack would rather you didn't think about.

It's also the one that most undermines the "no sugar" pitch. Powdered maltitol has a glycaemic index of around 35. That's lower than sugar, but it's not nothing, and it's far from the zero-impact sweetener the packaging implies. Worth knowing too that maltitol syrup, the cheaper form used in a lot of products, runs higher again, closer to a GI of 52, almost up at sugar's level. Eat a couple of bars and the blood-glucose effect adds up. At around 2.1 calories per gram it isn't saving you as much as the "half the calories of sugar" line suggests either.

Then there's your gut. Maltitol is poorly absorbed in the small intestine, so most of it travels down to the large intestine where your gut bacteria ferment it. That fermentation is what produces the bloating, gas, cramping and, at higher doses, the diarrhoea that maltitol is notorious for. Of the common sugar alcohols, it's the most likely to cause that kind of distress at the serving sizes bars actually use. If you've ever eaten a "healthy" bar and felt wrecked an hour later, maltitol is a prime suspect.

Erythritol (E968)

On paper, erythritol looks like the good one. It has near-zero calories, about 0.2 per gram, low enough that food labels round it to zero, and a very low glycaemic impact, so it won't spike your blood sugar. And unlike maltitol, about 90% of it is absorbed in the small intestine and excreted unchanged in your urine, rather than being fermented in the colon. That means far less of the bloating and gas that maltitol causes. It's made by fermenting glucose, usually from corn. For years it was considered the best-tolerated sugar alcohol going, and on the digestive front, it largely is.

The reason it's no longer that simple is a pair of studies out of the Cleveland Clinic.

In 2023, a team led by Dr Stanley Hazen published research in Nature Medicine examining erythritol and cardiovascular risk across more than 4,000 people. They found that patients with the highest blood erythritol levels were roughly twice as likely to experience a major cardiac event, a heart attack, stroke or death, over the following three years compared to those with the lowest levels. The researchers also showed, in lab and animal work, that erythritol made platelets more prone to clotting, which is a plausible mechanism for how it could raise that risk.

A 2024 follow-up, published in Arteriosclerosis, Thrombosis and Vascular Biology, tested this directly in healthy volunteers. After drinking a dose of erythritol equivalent to what's in a typical sugar-free food, every single participant showed a sharp increase in platelet reactivity, the clumping behaviour that contributes to clots. Glucose, given to a comparison group, produced no such effect. The same research group reported similar findings for xylitol in the European Heart Journal that year.

Now the honest caveats, because they matter. The 2023 study shows association, not proof of cause: people with high erythritol levels had more cardiac events, but that on its own doesn't prove the erythritol caused them. The follow-up is a small, short-term study measuring a marker of clotting risk, not actual heart attacks. And erythritol remains classified as safe by both FSANZ and the FDA. What you've got is emerging evidence, not a settled verdict.

But emerging evidence pointing this direction, from a serious research group, on a sweetener consumed by millions, is enough that the researchers themselves have called for erythritol's safety to be re-evaluated. That's not nothing. If you're choosing what goes in your body daily, "the science is still developing, but it's developing ominously" is a reasonable thing to weigh.

Xylitol (E967)

Xylitol sits in the middle on digestion: better tolerated than maltitol, not as clean as erythritol, with around 2.4 calories per gram. You'll find it in some protein bar coatings and a lot of products that lean on a "natural" image, since it occurs in small amounts in plants.

It now carries the same asterisk as erythritol. In June 2024 the same Cleveland Clinic group published work in the European Heart Journal showing that high blood xylitol levels were associated with around 50% higher cardiovascular event risk in a large patient group, and that a dose typical of sweetened foods sharply increased platelet reactivity in healthy volunteers. Same caveats apply: association rather than proof, an approved ingredient, evidence still building. But it's the second sugar alcohol in two years to attract this kind of finding, which is worth noting in its own right.

One genuinely practical warning while we're here: xylitol is extremely toxic to dogs, even in small amounts. If you keep xylitol-sweetened bars or snacks around the house, keep them well away from the dog.

Sorbitol (E420)

Sorbitol is absorbed slowly and incompletely, at about 2.6 calories per gram. Its defining feature is a well-documented laxative effect at doses above roughly 20 grams, and that threshold isn't as far off as it sounds. A bar or two relying on sorbitol for sweetness can get you there, with predictable results. It turns up less often than maltitol in Australian protein bars, but it's common enough in sugar-free sweets and some "low-carb" products that it's worth recognising on a label.

Isomalt (E953)

Isomalt is less sweet than sugar and shows up more in hard confectionery and coatings than in protein bars proper. It behaves like the other poorly absorbed polyols, capable of causing the same digestive upset at higher doses. You're less likely to meet it in a bar, but now you'll know it when you do.

At A Quick Glance:

The "no added sugar" label trap

Here's the mechanism that ties all of this together, and the single most useful thing to take from this article.

Under Australian food standards, sugar alcohols are not counted as added sugars. They also don't appear in the "sugars" line of the nutrition information panel, because technically they aren't sugars. They sit in a separate category entirely. What that means in practice is that a bar can contain 15 or 20 grams of maltitol, taste like a chocolate dessert, and still legally print "no added sugar" on the front of the pack with the sugars line on the panel reading low.

So the panel, the thing most people glance at, tells you almost nothing about whether a bar is sweetened with polyols. You can check the sugars number, see it's low, and walk away with a bar that's two-thirds sugar alcohol by sweetening. The number isn't lying. It's just not measuring the thing you think it's measuring.

The only place the truth lives is the ingredients list. That's where sugar alcohols have to be declared, either by name or by E number. Scan it for maltitol, erythritol, xylitol, sorbitol, isomalt, or any E number in the 900s and the 420 for sorbitol. Pay particular attention to anything in brackets after the chocolate coating, because that's where maltitol usually hides.

This is why reading the panel is not enough, and why we always come back to the same advice: turn the bar over and read the full ingredients list. If you want the complete method, we've put together a separate guide on how to read a protein bar label. And if you're wondering whether the category is worth the trouble at all, that's a fair question we've tackled in are protein bars actually healthy.

Sugar alcohols and your gut (FODMAPs)

If you've heard the term FODMAP, this is where sugar alcohols intersect with it. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols, a group of carbohydrates that are poorly absorbed in the small intestine and fermented by bacteria further down. That fermentation is what triggers bloating, wind and cramping in people whose guts are sensitive to it. The P on the end of FODMAP is polyols, which is to say sugar alcohols.

With one exception, every sugar alcohol in this article is a FODMAP. Maltitol, xylitol, sorbitol and isomalt all qualify, which is the underlying reason maltitol in particular is such a reliable cause of gut trouble. If you have IBS or a gut that lets you know when it's unhappy, a bar sweetened with any of these is a fairly direct route to a bad afternoon.

The exception is erythritol. Because most of it is absorbed in the small intestine before it ever reaches the fermenting bacteria, erythritol is generally considered low-FODMAP and is the gentlest of the group on digestion. Which leaves it in an awkward spot: the best-tolerated sugar alcohol for your gut is also the one now carrying the cardiovascular questions from the section above. There isn't a polyol that comes out of this clean on every measure.

So should you avoid them?

The honest answer is that it depends on which one, how much, and who you are.

Sugar alcohols are approved by FSANZ and most people tolerate small amounts without trouble. If a bar you like has a bit of erythritol in it and your gut and your heart are both healthy, this isn't worth losing sleep over. Context matters, and one bar is not a health crisis.

That said, the picture is not flattering the more closely you look. Maltitol, the most common one in Australian bars, raises blood glucose more than the "no sugar" framing admits and is the most likely of the lot to leave you bloated and cramping. Erythritol and xylitol, the two often marketed as the cleaner options, have both attracted cardiovascular findings serious enough that the researchers behind them are calling for a safety re-evaluation. Sorbitol will move your bowels if you have a couple of bars. And every one of them except erythritol is a FODMAP. There's no single sugar alcohol that wins on every front, which is the real takeaway: the category is a series of trade-offs, not a free lunch.

For my money, the more interesting question isn't which sugar alcohol is least bad. It's why a snack needs an engineered sweetener at all. There's another way to make a bar taste good, which is to sweeten it with actual food. At Raised we use dates and fruit rather than polyols, and the distinction isn't just philosophical. The sugars in a whole food like dates come bound up with fibre, which slows their absorption and blunts the blood-glucose response, and they arrive alongside the micronutrients and polyphenols that come in the fruit. Dates themselves sit at a low glycaemic index, around 50, for exactly that reason. It's sweetness your body has the machinery to handle, rather than a compound engineered to slip past a nutrition panel. If you want to see which bars actually take this approach, we've listed them in our guide to protein bars without artificial sweeteners.

None of this requires you to be precious about it. Read the list, know what the sweetener is, and decide what you're comfortable with. That's the whole game.

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What to look for on a label

Here's the whole article in practical form, for next time you're holding a bar in the supermarket.

Ignore the front of the pack. "No added sugar" and "low sugar" can both be true while the bar is sweetened with polyols, so those claims don't answer the question you're asking. Skip the nutrition panel too, at least for this purpose, because sugar alcohols don't show up in the sugars line.

Go straight to the ingredients list and read all of it. Scan for maltitol, erythritol, xylitol, sorbitol and isomalt by name, and for E numbers in the 900s along with 420 for sorbitol. Check the coating specifically, since that's where maltitol most often turns up. If you find one, you now know what it is and what it does, and you can decide whether you care.

And if you'd rather sidestep the whole question, the move is simple: look for a bar whose sweetness comes from food you recognise. If the list reads like dates, fruit and nuts rather than a chemistry shelf, you already have your answer. While you're training your eye on ingredients lists, it's worth knowing what are natural flavours and why a bar that's clean on sweeteners can still hide behind that one.