Fructose is a monosaccharide, a component of some disaccharides. It is the sweetest of all simple sugars; it delivers, like other carbohydrates, 4 calories per 1 g. Fructose absorption occurs in the duodenum according to the concentration gradient. It is the highest when the same amount of glucose is absorbed at the same time. Absorption also improves adaptively with higher dietary fructose intake. Fructose is a substrate in the lipogenesis process (a precursor of acetyl-CoA and 3-phosphoglycerol aldehyde), leading to the formation of triglycerides, which, in the absence of fructose metabolism regulation, may contribute to dyslipidemia and nonalcoholic fatty liver disease. Excessive consumption of fructose may also increase the formation of uric acid in the liver and thus increase the risk of cardiovascular disease and contribute to the accumulation of adipocytes in the adipose tissue. The effect of fructose on the reduction of insulin sensitivity of tissues, and thus on the development of type 2 diabetes and metabolic syndrome, is also described. Until now, no recommendations for population have been issued regarding the consumption of fructose alone. The WHO recommends – to both adults and children – limiting the intake of simple sugars to 10% of the energy value of the diet. Reduction in fructose consumption is recommended to people with diabetes and cardiovascular diseases. Most fructose is found in sweet drinks and products sweetened with sucrose, fructose syrup and fructose. There have been reports of various health effects of fructose syrups and fructose naturally occurring in products.

24.1.2019