Find out about lactose intolerance, including symptoms, how it's diagnosed, treatment and what causes it. Lactose is a natural, complex sugar produced in all mammalian milk that’s difficult to breakdown unless you have lactase, a protein, in your small bowel. Another reason is that lactose intolerance tends to be under-reported: most lactose-intolerant individuals can tolerate at least some lactose before they show symptoms, and their symptoms differ in severity. Lactose is a sugar naturally found in dairy products like milk, butter, yogurt, and more. Learn which 5 foods to avoid for lactose intolerance. Lactose is a major disaccharide present in milk. It is composed of two simple sugars, glucose and galactose. Cow, goat, and buffalo milk contains less lactose than human milk. It has several applications in the food industry. The positive and negative health-related effects of lactose are reported, focusing on the condition of lactose intolerance, for which an adequate lactose-free diet has to be followed to avoid symptoms that impairs quality of life. Lactose Lactose diagram Lactose is a disaccharide that is made up of galactose and glucose molecules. Lactose makes up around 2-8% of the solids in milk. The name comes from the Latin word for milk, plus the -ose ending used to name sugars. Lactose is found in some milk products. Lactose intolerance is a condition that makes it hard to digest the sugar in milk and milk products, called lactose. People with lactose intolerance often have diarrhea, gas and bloating after eating or drinking foods containing lactose. Therefore, this review will briefly summarise lactose metabolism, critically review the literature relating to the utility of lactose for athletes, highlight potential risks of lactose consumption and suggest areas for future research (Table 2). Lactose is a disaccharide composed of galactose and glucose, which form a β-1→4 glycosidic linkage. Its systematic name is β- D -galactopyranosyl- (1→4)- D -glucose.