Isomalt is a sugar substitute and a sugar alcohol that is processed from real sugar made from beets. The German company PALATINIT, founded in 1979, manufactures it. Isomalt was made by the early 1980s but not approved for use by the US Food and Drug Administration (FDA) until 1990.

In some forms Isomalt is blended with other non-sugar sweeteners like sucralose so it has approximately the same sweetness as sugar, but does not bake or quite react in the same way sugar does. For instance you can’t caramelize isomalt. Further, a few forms of isomalt sold for baking, like Diabetisweet, are often quite bitter. The treatment to granulate isomalt involves treating the sugar with acesulfame potassium, and results in an undesirable taste.

Nevertheless, it’s quite common to find isomalt used as a sugar substitute, particularly in sugar free or dietetic foods. Unlike regular sucrose, isomalt does not tend to raise blood glucose levels and is considered safe for consumption by diabetics. Animal studies with suggest the product is not carcinogenic or toxic.

This does not mean that isomalt can’t create problems, especially when consumed in large quantities. Studies on people taking isomalt have linked the substance to a high rate of stomach upset, gas and diarrhea. Even in relatively low doses, isomalt can cause diarrhea in about 10% of women who take it and about 4% of men. Just as with sugar, it’s a good idea to keep consumption of isomalt to a minimal amount, more so for the stomach upset it may cause than because of any long-term negative effects.

Isomalt is not completely without calories. It contains roughly half the calories of sugar. That’s about eight calories per teaspoon. So though it will lower calorie intake, it can't be used in zero calorie sodas. On the plus side, it won’t degrade your teeth, as does regular sucrose. Some toothpastes now contain isomalt to sweeten the toothpaste without causing cavities.

The substance has also been shown to prolong shelf life, and you may find it as a typical ingredient in breakfast cereals or crackers. You’ll also find isomalt in many different hard candies and in a variety of other products. Usually the amounts added to baked goods are relatively small and won’t cause tummy upset.

The reason that isomalt may prove upsetting to the stomach is because the body recognizes it as a dietary fiber instead of as a simple carbohydrate. Therefore, like most fibers, it can increase bowel movements and it passes through the bowel in virtually undigested form. Like other dietary fibers, regular consumption of isomalt might eventually lead one to become desensitized to it, decreasing the risk of stomach upset.