They occur both naturally and as ingredients in many foods. The most familiar sugar is sucrose. It is made of two simple sugars, fructose and glucose. Fruits and vegetables naturally contain fructose and glucose. During digestion, all of these sugars except lactose break down into fructose and glucose.
Lactose breaks down into glucose and galactose.
Sugars play important roles in foods. They add taste, texture and color to baked goods. They provide energy for yeast used in baking bread. They add body to yogurt. They help balance acidity in tomato sauces and salad dressings.