Riboflavin (vitamin B2)
Riboflavin functions as a coenzyme in a wide variety of reactions that take place in the body. Riboflavin is required to release energy from protein, carbohydrate and fat. It is also involved in the transport and metabolism of iron in the body and is needed for the normal structure and function of mucous membranes and the skin.
According to UK surveys, intakes of riboflavin are low in a number of population subgroups, in particular teenage girls (over 20% have intakes below the LRNI), young women (15% of 19-24 year olds below the LRNI) and women over 65 years living at home (10% of those 65-84, 15% of those over 85 years with intakes below the LRNI). A low status of riboflavin is also common but there is no clear deficiency disease because there is very efficient conservation and reutilisation of riboflavin in tissues; therefore deficiency is never fatal. Deficiency is characterised by dryness and cracking of the skin around the mouth and nose and a painful tongue that is red and dry (magenta tongue).
No toxic or adverse reactions to riboflavin in humans have been reported. The body excretes excess riboflavin in urine.
Milk, eggs, fortified breakfast cereals, liver, legumes, mushrooms and green vegetables are all sources of riboflavin.