Summary: Fructose is a monosaccharide belonging to FODMAPs, it is a digestive-resistant carbohydrate with a low degree of absorption in the digestive tract, which undergo rapid fermentation in the intestines. In food products, it occurs in free form in fruits and honey, in mixed form in sucrose in combination with a glucose molecule and in the form of polymers as fructooligosaccharides. The term fructose intolerance refers to two separate disease entities – congenital disorders of fructose metabolizm (fructosemia) and malabsorption of fructose from the gastrointestinal tract. Symptoms of fructosemia appear in infants after the inclusion in the diet of foods containing sucrose or fructose. In breastfed infants, the symptoms of fructose appear when products containing fructose (most often fruit and vegetable meals) are included in the diet, they occur about 5–6 months of age. The clinical picture of fructosemia is extremely diverse, probably depending on the individual, residual activity of fructose-1-phosphate Aldolase B. Most often there are vomiting, jaundice, enlargement of the liver, urinary tract infection, hypoglycemia. Fructose malabsorption occurs in about 30% of healthy people, and among patients with functional gastrointestinal disorder it accounts for 45%. The predominant clinical signs are abdominal pain, bloating, gas, overflowing, diarrhea or constipation. Symptoms occur about 0.5–2 hours after eating food containing fructose. For the treatment of both forms, a diet is used with a restriction of the consumption of foods containing fructose.