Sorbitol crystals. Cross-polarised light micrograph of grown crystals of sorbitol. Sorbitol (or glucitol) is a sugar that is found in everyday fruits. It is used as an artificial sweetener, having very few calories, but has laxative side effects. It is thought that the laxative effect of prunes is largely due to sorbitol. Magnification: x19 when printed 10 centimetres wide.