Vitamin B2, molecular model. Vitamin B2 (riboflavin) is an essential nutrient that humans are unable to produce and need to obtain from their diet. It is found in beans, yeast, almonds, green vegetables and dairy products. Vitamin B2 is needed to break down carbohydrates, fats, and proteins in the body. Deficiency can lead to cracked lips, mouth ulcers, excess fluid in the mucous membranes and itchy eyes that are sensitive to light. Vitamin B2's chemical formula is C17H20N4O6.Atoms are represented as spheres and are colour-coded: carbon (C, grey), hydrogen (H, turquoise), nitrogen (N, blue) and oxygen (O, red).