Vitamin B2 (riboflavin) is a water-soluble B vitamin that serves as a building block for two coenzymes, FAD and FMN, which are involved in energy production at a cellular level. Beyond energy metabolism, riboflavin plays a role in the metabolism of other B vitamins (including folate, B6, and niacin), supports healthy skin and eye function, and contributes to iron metabolism and red blood cell production.
Riboflavin deficiency (ariboflavinosis) is relatively uncommon in people eating a varied diet, as B2 is found in many common foods including dairy products, eggs, meat, leafy green vegetables, and fortified cereals. Those at higher risk of deficiency include people who avoid dairy and meat, individuals with gastrointestinal conditions that impair absorption, heavy drinkers, and people with chronically restricted or monotonous diets.
The classic signs of riboflavin deficiency affect the mouth and skin: cracked or sore lips (angular cheilitis), a swollen red tongue (glossitis), skin rashes around the nose and mouth, and increased sensitivity to light. Because riboflavin is needed for the metabolism of other B vitamins, a deficiency in B2 can also impair the utilisation of folate and B6, potentially affecting those pathways as well.
There is growing interest in riboflavin's role in migraine management. Some research suggests that high-dose B2 supplementation may reduce migraine frequency in certain people, and practitioners investigating migraines may request a baseline riboflavin level before recommending supplementation.
Riboflavin is light-sensitive, which is relevant to sample handling (the laboratory takes appropriate precautions). It is also water-soluble, meaning excess amounts are excreted in urine rather than accumulating, which makes toxicity from dietary intake extremely unlikely. A bright yellow colour in urine after taking B2 supplements is harmless and simply reflects excretion of the excess.
To measure circulating riboflavin and identify levels that may be insufficient to support normal energy metabolism and tissue health.
