Lactose is a major type of sugar found in milk and milk products. Lactose is a disagreed (two sugar units) composed of one glucose unit and one galactose unit. Commonly known as "milk sugar", lactose is the main carbohydrate in milk. Dairy products (other than milk) vary in lactose content. Natural cheeses for example contain lower lactose contents compared to milk. This is due to the removal of lactose-whey and the conversion of lactose to lactic acid by select micro organisms in cheese-making.