Sugar substitutes are used as an alternative to sugar in foods. Together with sweeteners, they form the functional class “sweeteners” of food additives approved in the European Union. The most important sugar substitutes include the sugar alcohols sorbitol (E 420), xylitol (E 967), mannitol (E 421), maltitol (E 965), isomalt (E 953), lactitol (E 966), as well as erythritol (E 968) and fructose (fruit sugar, monosaccharide; simple sugar). Fructose is not considered a food additive in the legal sense and therefore does not have an E number. Compared with the carbohydrates sucrose (“household sugar“, disaccharide; twofold sugar) and glucose (monosaccharide; single sugar), sugar substitutes have only a minor influence on the glucose serum level (blood sugar level). In addition, their metabolism is largely insulin-independent. For these reasons, sugar substitutes are used in particular in dietetic foods for diabetics instead of the usual household sugar and, from a chemical point of view, are not sugar. Fructose in particular has long been considered the preferred substitute for sucrose and glucose because insulin is not required in the initial stages of fructose metabolism. If fructose is consumed in small to moderate amounts, i.e. < 50 g/day or < 10% of daily energy, its proven advantages, such as insulin-independent metabolism, come into play. Ingestion of larger amounts of fructose, on the other hand, promotes obesity (overweight) and the development of metabolic syndrome. Human studies have shown that the high consumption of fructose promotes the formation of new fats (liponeogenesis) and the storage of fats in adipose tissue and in the liver, and is thus associated with non-alcoholic fatty liver disease (NAFLD). NASH: nonalcoholic steatohepatitis), which is considered an early sign of metabolic syndrome. Furthermore, heavy consumption of fructose leads to elevated LDL cholesterol and triglyceride levels. According to current scientific knowledge, persons with diabetes mellitus no longer require special dietary foods, since the same recommendations for a healthy diet now apply to them as to the general population. The energy value of sugar alcohols averages 2.4 kcal/g, which is lower than that of household sugar, but must still be included in the calorific value calculation by the diabetic. The energy value of fructose and sucrose is 4.1 kcal/g. The sweetening power of sugar alcohols (with the exception of xylitol, whose sweetening power is only slightly lower than that of household sugar) is about 40-90% of conventional sugar and lower than that of sweeteners. However, the sweetening power of fructose is about 120% of the household sugar. Sugar substitutes are not cariogenic, which is why they are also found in chewing gum and toothpaste. Sugar substitutes are considered harmless to health. However, they are poorly absorbed in the small intestine and consequently enter the large intestine largely unchanged. Sugar substitutes have a hygroscopic (water-attracting) effect, i.e. they liquefy the stool. In high doses (more than 20-30 g/day), they can therefore cause diarrhea and flatulence, which is why they are not used in beverages. If a food contains more than 10% sugar substitutes, it must be labeled “May have a laxative effect if consumed in excess.” Furthermore, the sugar substitutes fructose and sorbitol (synonym: sorbitol; sorbitol syrup) are of particular relevance with regard to food intolerances. In the case of fructose intolerance (fructose intolerance), foods containing sucrose, inulin, sorbitol, honey and invert sugar should be avoided. In case of sorbitol intolerance, diet foods as well as chewing gums and lozenges should be avoided. Caution. People suffering from fructose intolerance or malabsorption should not consume sorbitol either, because sorbitol is converted into fructose in the metabolism. The incidence (frequency of new cases) of hereditary fructose intolerance (inherited disorder of fructose metabolism) is 1:20,000, while fructose malabsorption (acquired fructose intolerance) affects about 30-40% of Central Europeans.The prevalence of sorbitol tolerance is around 10%. People with fructose or sorbitol tolerance must therefore look very carefully at the list of ingredients in food.
