[The metabolism of monosaccharides and polyoles]

The metabolism and the various metabolic effects of the sugar substitutes fructose, sorbitol and xylitol have been studied and compared to those of glucose. Fructose, sorbitol, and xylitol were found to be metabolized almost completely in the liver, whereas glucose was metabolized only 20-30% by this organ. The sugars and polyols exhibit a number of common effects characteristic of carbohydrate metabolism. Some of them are for example increase in lactate concentration, increase in lactate-pyruvate ratio, decrease in the concentration of free fatty acids, and decrease in phosphate concentration. The only effect that is restricted to fructose, sorbitol, and xylitol, is the stimulation of uric acid biosynthesis. Though sugar substitutes may be regarded as precursors of glucose, they have only little effect on the increase of blood glucose concentration in normal subjects. This may be due to the glucose - fatty acid cycle. It is to be expected that the use of fructose, sorbitol, and xylitol in diabetes mellitus and under stress situations has certain advantages over glucose.