Erythritol (E968) is a natural sugar that is mass produced by unnatural means. Naturally occurring in some fermented foods and some fruits, this sugar alcohol can be digested to yield about 0.2 calories per gram, or about 5% of the energy in an equivalent amount of regular sugar. The European Union recently approved the use of erythritol as a sweetener but requires all sugar alcohols to be labeled as 2.4 calories per gram regardless of the actual caloric content.
Although erythritol is low in calories, it's about half as sweet as sugar and does not have a noticeable aftertaste. Unlike mannitol and xylitol, erythritol is poorly digested by the bacteria that live in the lining of the small intestine, so it does not cause gas unless it's consumed in amounts in excess of 50 grams (about 2 oz) a day. And erythritol has an unusual kind of chemistry that causes it to cool down juices and beverages to which it is added. This is a plus in processing fruit and vegetable juices.
You will occasionally see erythritol on the label fruit and vegetable juices. You won't see it on the label of some products that use just 0.5 g of erythritol with an even tinier amount (about 0.01 gram) of stevia extract. Just be sure not to consume more than about half a liter (2 cups) of any juice product that is sweetened with erythritol in any one day to avoid stomach rumbling, diarrhea, and flatulence. Erythritol has no long-term side effects.