Riboflavin (a.k.a. vitamin B2) is an essential, water-soluble vitamin that is integral to numerous biochemical reactions in the body, many of which are related to the conversion of food into energy.
      More specifically, riboflavin functions in the bound coenzyme forms flavin mononucleotide (FMN) and flavin-adenine dinucleotide (FAD) as a catalyst for various reduction-oxidation reactions in numerous metabolic pathways. One of its reactions, in the presence of vitamin B12, is involved in the formation of methionine from homocysteine.

      The most recent research on riboflavin suggests a RDI of 1.3 mg for adult males, and 1.1 mg for adult females. Figures for the recent National Academy of Sciences Dietary Reference Intakes study are based upon slightly different age ranges than those previously evaluated, accounting for the overlapping groups in the following table.

      There are numerous natural and fortified food sources for riboflavin. The most common include milk, bread products, whole grain products, pasta, rice, meats, fish and poultry, and vegetables, particularly beans, broccoli, turnip greens, asparagus, and spinach.
      Riboflavin is a light sensitive compound, so foods containing this vitamin should not be stored in direct sunlight otherwise the vitamin will be rapidly destroyed.

      Riboflavin deficiency (ariboflavinosis) is more common in the developed world than deficiencies of other vitamins, despite its ready availability from dietary sources. Typical manifestations of deficiency are sore throat, swelling and inflammation of the mouth and lips, dry, scaly skin, and visual impairment (usually extreme sensitivity to light), potentially leading to conjunctivitis and other eye disease. Usually these symptoms are accompanied by deficiencies in other vitamins of the B complex.

      Supplemental riboflavin is generally found in combination with other vitamins of the B complex, and in multivitamins. The usual application of riboflavin in this form, like thiamin (vitamin B1), is to supplement inadequate dietary intake. A typical multivitamin contains 1.7mg of riboflavin, which is 100% of the current Reference Daily Intake (RDI).

      There have been no definitive reports of health risks resulting from large doses of riboflavin, though few studies have focused directly on the potential of adverse effects. This is due, in part, to the lack of efficient absorption and high rate of excretion of the vitamin in the urine.
      The recent National Academy of Sciences Dietary Reference Intakes study does not set a Tolerable Upper Intake Levels (UL) for this vitamin due to a lack of adequate science. Their report does indicate, however, a so-called “exposure assessment” (an apparently unremarkable intake level) of approximately 7-11mg/day from both dietary and supplemental sources, based upon the highest mean riboflavin intake reported among adult men and women, respectively, of mixed age.

      There have been a few reports of the effects of riboflavin in relation to certain site-specific cancers, and its potential in reducing the risk of cataracts, but overall, the data are insufficient at this time to consider supplemental riboflavin as a preventive measure for reduction of risk in these disorders.
      Supplemental riboflavin has also been associated with the potential risk reduction of migraine headaches, though this application of the vitamin needs to be evaluated in much more detail before any definitive effects can be assessed.