galaktoz

Galactose is a monosaccharide sugar of the aldohexose class. It has the chemical formula C6H12O6 and is a C-4 epimer of glucose. It is a reducing sugar and an aldose.

In nature, galactose occurs mainly as a constituent of lactose, the disaccharide in milk. Lactose is hydrolyzed by lactase in the small intestine to glucose and galactose, which are absorbed into the bloodstream. In humans, galactose is metabolized mainly in the liver via the Leloir pathway, where it is converted to galactose-1-phosphate and eventually to UDP-galactose for glycoprotein and glycolipid biosynthesis and to enter energy metabolism as glucose-1-phosphate.

Clinical significance: Inherited disorders of galactose metabolism include classic galactosemia caused by deficiency of galactose-1-phosphate uridylyltransferase (GALT); more rarely deficiencies of galactokinase (GALK1) or UDP-galactose 4'-epimerase (GALE). Newborn screening detects these conditions; treatment requires strict dietary restriction of galactose and lactose to prevent serious complications such as liver dysfunction, cataracts, and intellectual disability.

Industrial and dietary aspects: In dairy processing and food science, galactose is used as a reference sugar; it is also produced industrially by hydrolysis of lactose. Galactooligosaccharides, derived from lactose, are used as prebiotics in foods and supplements.