Riboflavin

Question 1

Explain structure of Riboflavin

Answer 1

flavin attached to a ribitol

Question 2

coenzyme forms

Answer 2

flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)

Question 3

Is riboflavin absorbable as FMN/FAD

Answer 3

No. it must be broken down to be absorbed

Question 4

Food sources of riboflavin

Answer 4

milk, eggs, meat, legumes

Question 5

How is riboflavin destroyed

Answer 5

sunlight

Question 6

How does riboflavin exist in food sources

Answer 6

free form, FMN, and FAD

Question 7

What does riboflavin have an affinity for

Answer 7

protein

Question 8

Digestion

Answer 8

riboflavin attached to proteins is freed by HCL or other stomach acids

Question 9

what enzyme breaks down FAD to FMN

Answer 9

FAD pyrophosphatase

Question 10

what enzyme breaks FMN down to riboflavin

Answer 10

FMN phosphatase

Question 11

What affects riboflavin bioavailability

Answer 11

divalent metals (copper, zinc, manganese)

Question 12

How is free riboflavin absorbed

Answer 12

via sodium dependent carrier mechanism in proximal SI (active transport)

Question 13

How is riboflavin stored

Answer 13

converted to FAD within cells; liver, kidney, brain

Question 14

How do FMN and FAD function

Answer 14

bound to enzymes within the oxidative systems; accepts one electron at a time

Question 15

Where is riboflavin used

Answer 15

ETC, PDH complex, succinate dehydrogenase, fatty acid oxidation

Question 16

Electron Transport Chain function

Answer 16

complex I/II: transfer of electrons from NAD to FMN to CoQ

Question 17

PDH complex function

Answer 17

FAD serves as intermediate electron carrier

Question 18

Succinate dehydrogenase function

Answer 18

FAD converts succinate to fumarate, forms FADH2

Question 19

Fatty acid oxidation function

Answer 19

fatty acyl CoA dehydrogenase requires FAD

Question 20

What 3 vitamins require FAD to metabolize

Answer 20

vitamin B6, vitamin A, folate

Question 21

Riboflavin excretion

Answer 21

limited metabolism prior to urinary excretion; may be excreted in feces/bile

Question 22

Riboflavin DRI/RDA

Answer 22

1.3 and 1.1mg (may be related to macronutrient intake)

Question 23

Riboflavin deficiency

Answer 23

ariboflavinosis

Question 24

Ariboflavinosis

Answer 24

rarely occurs in isolation; occurs aftr 4 months of inadequate intake (skin issues and neuropathy)

Question 25

why might someone need increased riboflavin

Answer 25

conditions resulting in limited intake, altered metabolism (thyroid disease), increase urinary excretion (diabetes)

Question 26

is riboflavin ever toxic

Answer 26

none reported

Question 27

Assessment of riboflavin

Answer 27

activity of erythrocyte glutathione reductase