RIBO-flavor

Question 1

What makes up Riboflavin

Answer 1

Isoalloxazine + Ribityl side chain

Question 2

What is the active form of Riboflavin?

Answer 2

The cofactors:
- FMN
-FAD

Question 3

What is required for the conversion of Riboflavin to FMN? FAD?

Answer 3

FMN requires Zn & ATP
FAD requires Mg & ATP (you get PP)

Question 4

What regulates the conversion of FMN and FAD

Answer 4

Thyroid hormone

Question 5

What is the main element FMN & FAD carry ?

Answer 5

2 H-atoms

Question 6

What is the metabolic roles of B2

Answer 6

Energy production (TCA,ETC,B-ox)
Regulation of redox statis
Detoxification (FMOs)
Conversion of vitamins (B6 and Folate)
Syn of Niacin from typtophan

Question 7

Where would you find B2 in TCA cycle

Answer 7

PDH (E3)
a-ketoglutarate to succinyl-coa
Succinate to fumarate (succinate dehydrogenase)

Question 8

Describe the role of B2 in ETC

Answer 8

Complex 2 (succinate to fumarate)
Complex 1 (NADH to NAD)

Question 9

Which step in B-ox requires B2

Answer 9

Acyl-CoA to trans-2 Enoyl-CoA

Question 10

Describe B2 absorption into the enterocyte

Answer 10

Enters as a FMN/FAD protein
Gastric acid + Intestinal proteases convert to FMN/FAD
FMN-phosphatase + PAD-pyrophosphatase convert to Riboflavin
[Low] RFT1&2
[high] >12 it can diffuse

Question 11

How is B2 metabolically trapped

Answer 11

When converted to FMN via RFK then to FAD via FADS
- Some FMN and all FAD is trapped

Question 12

What forms of B2 are able to travel in the plasma

Answer 12

FMN and riboflavin

Question 13

Where is the highest concentration of B2 found

Answer 13

little storage, highest in the liver
(1/3 FAD)

Question 14

What would reflect dietary intake of riboflavin?

Answer 14

Urinary excretion
little is stored, rapidly excreted two hours after ingestion
limited accuracy

Question 15

which form of riboflavin is most found in food?

Answer 15

2/3 as FAD

Question 16

Out of the products listed which would give me 1/3 of the RDA for B2: green leafy veg, enriched flour, meat, dairy and eggs?

Answer 16

Dairy and eggs
Bioavailability is related to digestibility of food

Question 17

Why might a vegetarian have better riboflavin status than a meat-based diet?

Answer 17

Riboflavin can be syn by bacteria in the large intestine and syn increases in veg diets

Question 18

RDA? UL?

Answer 18

RDA: 1mg
UL: none set

Question 19

What is the FAD effect?

Answer 19

A serum concentration test of glutathione reductase - if an increase in FAD when added would show deficiency
A:<20
M:20-40
D:>40

Question 20

Ariboflavinosis

Answer 20

Deficiency: stunted growth, lack of energy, cheilosis & glossitis, angular stomatitis, skin lesions, corneal vascularization

Question 21

Why is it hard to diagnose Ariboflavinosis

Answer 21

similar deficiencies as B6 (pyridoxine) because active form requires FMN

Question 22

With which other nutrients would you see a B2 deficiency?

Answer 22

Iron - conversion of Fe3-Fe2
Folate - conversion of oxidized folate

Question 23

Which populations are at risk for folate deficiency?

Answer 23

Low intake (Elderly/China/Wherever lacks dairy&meat)
Pregnancy
Disease states: (thyroid, diabetes, hyperbilirubinemia)