Remember this means it must be eaten every day stays only in the system about 5 hours has very little chance of building up to toxic levels is absorbed easily excess is excreted in the urine is very fragile and can be destroyed by light, heat, acids, alkalis, and even air. Riboflavin is part of a coenzyme used in energy metabolism . It supports normal vision and skin health. Symptoms of toxicity are not seen. Sources are milk, yogurt, cottage cheese, meat, leafy green vegetables, and whole grains.
Milk is by far the outstanding source.
Storage is so small that you need a source at every meal. Excretion of excess is in the urine. Pour milk just before eating so that the light will not destroy the riboflavin. Riboflavin is a dye - a bright yellow that shows up in your urine. Physicians sometimes add it to prescriptions as a marker to find out if you are taking your medication.