Tuesday, July 3, 2007

Dietary sources of Vitamin B2

Living cells require FMN and FAD as the prosthetic
groups of a variety of enzymes, and hence the fl avins
are found, at least in small amounts, in all natural unprocessed
foods. In most foods the predominant form
of vitamin B2 is protein-bound FAD. Yeast extract is
exceptionally rich in vitamin B2, and liver and kidney
are also rich sources. Wheat bran, eggs, meat, milk and
cheese are important sources in diets containing these
foods. Cereal grains contain relatively low concentrations
of fl avins, but are important sources in those
parts of the world where cereals constitute the staple
diet. The milling of cereals results in considerable loss
(up to 60%) of vitamin B2, so white fl our is enriched
by addition of the vitamin. The enrichment of bread
and breakfast cereals contributes signifi cantly to the
dietary supply of vitamin B2. Polished rice is not usually
enriched, since the yellow colour of the vitamin
would make the rice visually unacceptable. However,
most of the fl avin content of the whole brown rice is
retained if the rice is steamed prior to milling. This
process drives the water-soluble vitamins in the germ
and aleurone layers into the endosperm (Cooperman
and Lopez, 1991).

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