Vitamin B2, or riboflavin, is a vitamin that the body needs to produce energy and facilitate cell growth, function, and development. It is also used to metabolize drugs and fats. The vitamin is bright yellow. It is found in organ meats, eggs, milk, lean meats, and vegetables. Cereals and some grains are fortified with riboflavin. People who are vegetarian or vegan may become deficient in riboflavin. Supplemental riboflavin may be an effective treatment for people who suffer from migraines. Taking a riboflavin supplement may cause urine to turn a bright yellow color.