Riboflavin Flashcards
Explain structure of Riboflavin
flavin attached to a ribitol
coenzyme forms
flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)
Is riboflavin absorbable as FMN/FAD
No. it must be broken down to be absorbed
Food sources of riboflavin
milk, eggs, meat, legumes
How is riboflavin destroyed
sunlight
How does riboflavin exist in food sources
free form, FMN, and FAD
What does riboflavin have an affinity for
protein
Digestion
riboflavin attached to proteins is freed by HCL or other stomach acids
what enzyme breaks down FAD to FMN
FAD pyrophosphatase
what enzyme breaks FMN down to riboflavin
FMN phosphatase
What affects riboflavin bioavailability
divalent metals (copper, zinc, manganese)
How is free riboflavin absorbed
via sodium dependent carrier mechanism in proximal SI (active transport)
How is riboflavin stored
converted to FAD within cells; liver, kidney, brain
How do FMN and FAD function
bound to enzymes within the oxidative systems; accepts one electron at a time
Where is riboflavin used
ETC, PDH complex, succinate dehydrogenase, fatty acid oxidation
Electron Transport Chain function
complex I/II: transfer of electrons from NAD to FMN to CoQ
PDH complex function
FAD serves as intermediate electron carrier
Succinate dehydrogenase function
FAD converts succinate to fumarate, forms FADH2
Fatty acid oxidation function
fatty acyl CoA dehydrogenase requires FAD
What 3 vitamins require FAD to metabolize
vitamin B6, vitamin A, folate
Riboflavin excretion
limited metabolism prior to urinary excretion; may be excreted in feces/bile
Riboflavin DRI/RDA
1.3 and 1.1mg (may be related to macronutrient intake)
Riboflavin deficiency
ariboflavinosis
Ariboflavinosis
rarely occurs in isolation; occurs aftr 4 months of inadequate intake (skin issues and neuropathy)
