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. Lactose, carbohydrate containing one molecule of glucose and one of galactose linked together. Composing about 2 to 8 percent of the milk of all mammals, lactose is sometimes called milk sugar. Lactose is the sugar that’s in milk. Our bodies use an enzyme called lactase to break down that sugar so we can absorb it into our bodies. But people with lactose intolerance don’t have enough. 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 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. 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. 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. Begin with a lactose-free diet, then gradually reintroduce lactose-containing foods to see how your system responds. Some people with lactose intolerance can tolerate up to 12 grams (g) of lactose at one time, which is a cup of milk or a scoop of ice cream. 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).