COLLOIDAL MINERALS
RIBOFLAVIN
Riboflavin (vitamin B-2) is chemically known as 7,8-dimethyl-10 (1'-D-ribityl)isoalloxazine. In tissues there is a broad distribution
of flavin but little is present as free riboflavin. The majority is found in
flavocoenzymes [mainly flavin adenine dinucleotide (FAD) and lesser amounts
are in mononucleotide (riboflavin-5'-phosphate)(FMN). Levels of flavin range
from a few µg/g wet weight in skeletal muscle and intestine, and up to 30 to
35 µg/g in liver and kidney. Flavocoenzymes are largely non-covalently associated
within diverse flavoproteins, but some exist as 8a-linked
FAD.
As the catalytically operating moiety within bound flavocoenzymes, riboflavin
participates in oxidation-reduction reactions in numerous metabolic pathways
and in energy production via the respiratory chain. Flavoproteins participate
in both one- and two-electron transfers. They operate in pyridine nucleotide-dependent
and independent and independent dehydrogenations, reactions with sulfur-containing
compounds, hydroxylation, oxidative decarboxylations, deoxygenations, and reduction
of O2 to hydrogen peroxide following abstraction of hydrogen from substrates.
Deficiencies: Ariboflavinosis is characterized by weakness, sore throat,
hyperemia and edema of the pharyngeal and oral mucous membranes, cheilosis,
angular stomatitis, glossitis, seborrheic dermatitis, corneal vascularization,
and normochromic, normocytic anemia associated with pure red cell hypoplasia
of the bone marrow.
Clinical uses: Riboflavin is used therapeutically to ameliorate ariboflavinosis
resulting from diverse causes such as inadequate dietary intake, decreased assimilation,
rare genetic defects in the formation of specific flavoproteins, hormonal disorders
and after use of certain drugs. Also, riboflavin supplements are provided during
treatment of neonatal jaundice with phototherapy. The side chain of the vitamin
is photochemically destroyed as it is involved in the photosensitized oxidation
of bilirubin to more polar excretable compounds.
Diet recommendations: The Recommended Dietary Allowances range from
0.4 mg/d for early infants to 1.3 mg/d for women and 1.7 mg/d for men. An additional
0.3 mg/d is recommended during pregnancy and 0.5 mg/d for lactation.
Food sources: Small amounts of riboflavin, occurring largely as digestible
coenzymes, are present in most plant and animal tissues. Especially good sources
are milk, eggs, enriched cereals and grains, ice cream, liver, some lean meats,
and green vegetables such as broccoli. As much as a third of North American
intake is attributed to milk and other dairy products.
Toxicity: The limited capacity to absorb orally administered riboflavin
precludes its potential for harm. Riboflavin intake of many times the RDA is
without demonstrable toxicity. Nevertheless, the photosensitizing properties
of riboflavin raise the possibility of some theoretical, potential risks.
Recent research: A comprehensive assessment of the human biokinetics
for riboflavin absorption, transport, metabolism, and excretion has just been
completed. Ongoing studies of a more biochemical nature are leading to detailed
understanding of structures and mechanisms of numerous flavoproteins from diverse
organisms.
For further information:
McCormick, D.B. (1994) Riboflavin. In: Modern Nutrition in Health and Disease
(Shils, M.S., Olson, J.A. & Shike, M., eds.), 8th ed., pp. 366-375. Lea & Febiger,
Philadelphia, PA
Yagi, K., ed. (1994) Flavins and Flavoproteins. Walter de Gruyter, New York,
NY; Rivlin, R.S. (1996) Riboflavin. In: Present Knowledge in Nutrition (Ziegler,
E.K. & Filer, L.J., eds.), 7th ed. ILSI Press, Washington, DC.
RELATED ARTICLES
PROTEIN
SILICON
 De-Stress
Super Daily
MINERAL MUNCH
Colloidal
Minerals: Formula Plus
Pre Natal
What is
the use of MAGNESIUM ?
Biotic Code Products
for Immune System Health.
 Total Toddy
Ultra Toddy
VITAMINS:
|
