<P> Food and beverages that provide riboflavin without fortification are milk, cheese, eggs, leaf vegetables, liver, kidneys, legumes, mushrooms, and almonds . </P> <P> The milling of cereals results in considerable loss (up to 60%) of vitamin B, so white flour is enriched in some countries such as US by addition of the vitamin . The enrichment of bread and ready - to - eat breakfast cereals contributes significantly to the dietary supply of vitamin B. Polished rice is not usually enriched, because the vitamin's yellow color would make the rice visually unacceptable to the major rice - consumption populations . However, most of the flavin content of whole brown rice is retained if the rice is steamed (parboiled) prior to milling . This process drives the flavins in the germ and aleurone layers into the endosperm . Free riboflavin is naturally present in foods along with protein - bound FMN and FAD . Bovine milk contains mainly free riboflavin, with a minor contribution from FMN and FAD . In whole milk, 14% of the flavins are bound noncovalently to specific proteins . Egg white and egg yolk contain specialized riboflavin - binding proteins, which are required for storage of free riboflavin in the egg for use by the developing embryo . </P> <P> Riboflavin is added to baby foods, breakfast cereals, pastas and vitamin - enriched meal replacement products . It is difficult to incorporate riboflavin into liquid products because it has poor solubility in water, hence the requirement for riboflavin - 5' - phosphate (E101a), a more soluble form of riboflavin . Riboflavin is also used as a food coloring and as such is designated in Europe as the E number E101 . </P> <P> The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for riboflavin in 1998 . The current EARs for riboflavin for women and men ages 14 and up are 0.9 mg / day and 1.1 mg / day, respectively; the RDAs are 1.1 and 1.3 mg / day, respectively . RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements . RDA for pregnancy is 1.4 mg / day . RDA for lactation is 1.6 mg / day . For infants up to 12 months the Adequate Intake (AI) is 0.3 - 0.4 mg / day . and for children ages 1--13 years the RDA increases with age from 0.5 to 0.9 mg / day . As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient . In the case of riboflavin there is no UL, as there is no human data for adverse effects from high doses . Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs). </P>

Which sign or symptom is characteristic of a riboflavin deficiency