Vitamin B2, also known as riboflavin, is one of the eight B-complex vitamins. Riboflavin is a vitamin that is needed for growth and overall good health. It helps the body break down carbohydrates, proteins and fats to produce energy, and it allows oxygen to be used by the body. Riboflavin is also used for the development and function of the skin, lining of the digestive tract, blood cells and other vital organs.