Sorbitol, Mannitol, Isomalt | Sweetener Buying Guide

SORBITOL, MANNITOL & ISOMALT

2025 BUYING GUIDE

In my quest to explore all the sugar-free sweeteners in stores, I came across three sugar alcohols: sorbitol, mannitol, and isomalt. While two are natural, one is artificial. They're not zero-calorie, but provide 35% to 60% fewer calories than sugar. Whether you want to know how they’re made, how they bake, or if they have any downsides, this guide covers it all!

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HOW THEY COMPARE

Sorbitol, mannitol, and isomalt are slow-digesting carbohydrates known as polyols or sugar alcohols — despite containing neither sugar nor alcohol. Since they’re partially absorbed, they provide fewer calories than sugar.

Sorbitol, mannitol and isomalt don’t just sweeten recipes—they also help maintain a sugar-like texture. As bulk sweeteners, they add both weight and volume. This sets them apart from bulk-free sweeteners, which are highly concentrated and used solely for sweetness.

THE BASICS

Sorbitol and mannitol were among the first polyols to be commercially used as sweeteners, though their discovery dates back over a century.

Sorbitol was first discovered in the berries of the mountain ash tree (Sorbus aucuparia), which is how it got its name. Mannitol, named after "manna" — a sweet-tasting tree exudate — was historically referenced in the bible as a miraculous food that sustained people in the desert.

Are they natural or artificial?
Sorbitol and mannitol are natural sweeteners. Both are found naturally in a variety of fruits and vegetables. But because these sources contain too little for extraction, store-bought sorbitol and mannitol are not derived directly from them.

Instead, for large-scale production, sorbitol and mannitol are synthetically made from glucose and fructose, respectively. The most common and more cost-effective raw material for both polyols is cornstarch (glucose syrups).

The Food and Drug Administration classifies them as natural because they exist in nature AND are derived from natural materials. While the FDA acknowledges that some natural ingredients can be "manufactured artificially", here at WhatSugar, we refer to them as a synthetic sweeteners for clarity. You can read more about this HERE and HERE.

It’s important to note that synthetic does not mean artificial. Artificial sweeteners are those not found in nature [Check out or artificial sweetener buying guide]. Sorbitol and mannitol, even when produced from corn, are not considered artificial because they are chemically identical to those naturally present in fruits.

One the other hand, isomalt is different. Isomalt is an artificial sweetener because it does not occur in nature and is made from beet sugar (sucrose).

BREAKING THEM DOWN

Calories, Carbs & Digestive Issues

How do sorbitol, mannitol, and isomalt behave in our bodies?
A small portion of the amount ingested is slowly absorbed and converted into glucose.

The remaining unabsorbed amount travels to the large intestine, where it can be fermented by the microbiota (the beneficial microbes in the intestinal tract).

Sorbitol & mannitol have an unique behavior. They're slowly absorbed in the small intestine and metabolized by the liver, mostly as fructose. Fructose, unlike glucose, does not immediately increase blood sugar levels and is converted to glucose without insulin.

Sorbitol & mannitol don't significantly increase blood sugar levels [there is a time delay from when fructose is digested to when it becomes available as glucose].

Isomalt is hardly broken down and absorbed in the small intestine, being mainly fermented by the microbiota in the large intestine.

Are they zero-calorie sweeteners?
No, sorbitol, mannitol, and isomalt are not zero-calories.

Since 50% to 75% (or more) of the ingested amount is not metabolized, these sweeteners provide fewer calories than sugar—but not zero.

According to the FDA regulation for nutrition labels, the caloric value per gram of sorbitol is 2.6, mannitol 1.6, and isomalt 2.0. To compare:

Sorbitol: 2.6 cal/gram | ∼8 cal/tsp (3g) | ∼380 cal/cup
Mannitol: 1.6 cal/gram | ∼7 cal/tsp (4g) | ∼340 cal/cup
Isomalt: 2 cal/gram | ∼12 cal/tsp (6g) | ∼580 cal/cup
Sugar (sucrose): 4 cal/gram | 16 cal/tsp | 770 cal/cup

By law, a sweetener may be labeled calorie-free, no-calorie, or zero-calorie if it provides less than 5 calories per serving. Since sorbitol, mannitol, and isomalt exceed this threshold, they cannot be labeled as zero-calorie. Instead they're reduced-calorie sweeteners, meaning they provide at least of 25% fewer calories than sugar per serving.

So, sorbitol, mannitol, and isomalt offer a middle ground for those looking to reduce calories without completely eliminating them, making them a balanced choice between full-calorie sugars and zero-calorie sweeteners.

What's their glycemic index? What about net carbs?
The glycemic index (GI) of polyols reflects their potential to raise blood glucose levels. For reference, pure glucose has an arbitrary GI of 100. Polyols generally have a low glycemic impact with the following GI values:
Mannitol = 2
Sorbitol = 9
Isomalt = 2
This makes them a lower-GI alternative to sugar, with minimal effects on blood glucose levels.

Sorbitol, mannitol, and isomalt are technically carbohydrates and included in the “total carbohydrates” count on nutrition labels. However, because they are only partially digested, only about half of the carb content impacts blood sugar.

When calculating net carbs, only half the carbs from these sweetener should be counted. Learn more on my Carb Counter resource Carb Counter resource.
Can they cause gut issues? Are they safe for sensitive stomachs?
Like all sugar alcohols, a portion of what we eat remains undigested and reaches the large intestine. There, it can lead to bloating, stomach rumbling, flatulence, cramps, and diarrhea. These effects are similar to those experienced with high-fiber foods like beans.

Individual tolerance varies—some people are more sensitive than others. However, regular consumption can lead to adaptation, meaning stomach issues may lessen over time.

Among all sugar alcohols, the worst effects happen with sorbitol and mannitol. So, by law, products with sorbitol and mannitol must include a warning on their label stating "excess consumption may have a laxative effect".

If you have a sensitive stomach, be aware that sorbitol, mannitol and isomalt are FODMAPs — an acronym for carbohydrates known to trigger negative digestive issues.

PROS AND CONS

Advantages of Sorbitol, Mannitol & Isomalt:

Sweet taste – Provide sweetness while helping cut back on sugar. Sorbitol, mannitol, and isomalt are about half as sweet as table sugar; 1 teaspoon of sugar = 2 teaspoons of sorbitol/mannitol/isomalt.
Lower in calories – Offer 35% to 50% fewer calories than sugar
Bulking properties – Add weight and volume to foods, impacting mouthfeel and texture, as regular sugar does
Digestive health benefits – May act as prebiotic.
Non-cariogenic – Not fermented by bacteria that cause cavities. They are referred to as Noncariogenic Carbohydrate Sweeteners by the Food and Drug Administration. Their label may carry health claims such as "does not promote," "may reduce the risk of," "useful in not promoting" dental caries.

Disadvantages of Sorbitol, Mannitol & Isomalt:

Do not brown or caramelize
Sorbitol, mannitol, and isomalt do not brown or caramelize like sugar. Unlike glucose and fructose, they lack an exposed carbonyl (C=O) group, which is essential for browning reactions. As a result, baked goods made with sorbitol, mannitol, and isomalt won’t develop a golden color the way they do with regular sugar.
Have a cooling effect
Sorbitol, mannitol, and isomalt crystals create a cold sensation when they dissolves in the mouth. This happens because they absorb energy from their surroundings (your mouth) as they dissolve, similar to the feeling of sucking on a mint—but without the mint flavor. While all polyols have a cooling effect, the sensation from sorbitol, mannitol, and isomalt is milder compared to xylitol and erythritol.
Often associated with adverse digestive issues
Consuming too much sorbitol, mannitol, or isomalt is often associated with bloating, stomach rumbling, flatulence, cramps, and diarrhea.
Sorbitol, mannitol, and isomalt are a FODMAPs carbohydrates.
Storage & Moisture Sensitivity
Sorbitol is highly hygroscopic, meaning it absorbs moisture from the air. To prevent clumping and maintain its quality, it should be stored in an airtight container. Mannitol and isomalt, on the other hand, have low hygroscopicity, so they can be stored in a sugar bowl on the table without absorbing much moisture. Among the three, isomalt has the highest resistance to humidity, making it the most stable for long-term storage in open air.

YOUR OPTIONS: PURE VS BLENDED

Mannitol is only available in powder form due to its low solubility—just 22g dissolves in 100 mL of water.

Isomalt comes in both granules and fine powder and is widely used in hard candy making and sugar work. It doesn’t crystallize, retains a glossy appearance, and is easy to color and flavor. Unlike regular sugar, isomalt stays flexible for longer, making it ideal for intricate sugar decorations.

Sorbitol, however, is sold in two forms: