MODULE 2: B1, B2, B3, B6

Question 1

** General function of B vitamins

Answer 1

• ENERGY (B1,B2,B3 = ENERGY) - energy releasing

- Blood cell production/hematopoietic

Question 2

** How is alcohol involved with deficiency of certain B vitamins

Answer 2

Alcohol INHIBITS ABSORPTION of B vitamin, B1 (thiamin) especially

B1 depletion (due to alcohol) associated with certain neurological disorders

Question 3

** Which B vitamin involved in nerve conduction/transmission

Answer 3

B1/Thiamin

Question 4

** B1 coenzyme and non-coenzyme main functions

Answer 4

Coenzyme:

1. Energy Transformation
2. NADPH production (pentose phosphate pathway)

Non-coenzyme:
1. Membrane and nerve conduction

Question 5

** Thiamin’s function in terms of energy (what type of carboxylation involved in?)

Answer 5

Involved in ENERGY TRANSFORMATION

Acts as coezyme for

1. Conversion of pyruvate of acetyl-CoA (requires TDP)
2. Pentose-phosphate/Hexosmonphosphate shunt
3. **OXIDATIVE DECARBOXYLATION reaction in Kreb cycle (TDP required for oxidative decarboxylation of alpha ketoglutarate)

Question 6

What important substances are produced via the Pentose-Phosphate pathway/Hexosmonophosphate shunt?

Answer 6

1. 5 CARBON SUGARS (eg. DNA/RNA)

2. NADPH (important electron donor in electron transport chain)

Question 7

** T/F only carboxylases (add COO group) require biotin as a coenzyme?

Answer 7

T

Question 8

** B6 and heme synthesis

Answer 8

B6 as PLP acts as coenzyme that is necessary in the first step of heme synthesis

Question 9

** B6 functions importantly in all of the following:

Answer 9

1. Energy production (transamination, decarboxylation, dehydration/deamination)
2. heme synthesis
3. Fatty acid/sphingolipid synthesis
4. Niacin synthesis
5. Nuclei acid synthesis
6. Glycogen degradation (gluconeogenesis)
7. NON COENZYME: gene expression (regulates)

Question 10

** In excess of water soluble vitamin intake, what does body do?

Answer 10

Results in urinary excretion of (intact) vitamin

Question 11

** B6 deficiency can be seen with what type of anemia?

Answer 11

Hypochromic (pale RBCs because low HbG), Microcytic (small RBCs) anemia

Question 12

** Symptoms of B6 deficiency

Answer 12

SEBORRHEIC DERMATITIS 
Fatigue
Confusion 
Peripheral neuropathy 
Glossitis 
** Hypochromic, microcytic anemia 
Hyperhomocysteinemia

Question 13

** How to access for B6 deficiency (functional v serum)

Answer 13

Serum = PLP

Functional = Urinary test of XANTHURENIC ACID (high X = low B6)

Question 14

** Upper tolerable limit of B6 (in mg)

Answer 14

100mg/day

Question 15

** Thiamin testing?

Answer 15

Serum & Urine TDP/Thiamin (decreased urinary excretion = decreased B1 status)

• Measuring B1 dependent enzyme TRANSKETOLASE activity

Question 16

** Major functions of B vitamins

Answer 16

1. ENERGY (releasing)

2. BLOOD CELL FORMATION/HEMATOPOIESIS

Question 17

** Vitamins that can result in cheilosis

Answer 17

B2**
B3
B6**

Question 18

** Consequences of Thiamin deficiency

Answer 18

Beriberi = nervous system and cardiac dysfunction

• Enlarged heart
• Tachychardia
• Neuropathy
• Changes in reflexes
• Ataxia
• Ocular changes

Question 19

** Which B vitamins are associated with NEUROPATHY?

Answer 19

B1
B2
B6
B12

Question 20

** Thiamin’s function in terms of sodium channels and nerve impulse generation

Answer 20

Thiamin REGULATES sodium channels/sodium channel permeability

Thiamin (as TTP) important for nerve impulses because:

• necessary for synaptic protein synthesis
• necessary for acetyl CoA conversion (CoA crucial for MYELINATION therefore NERVE IMPULSE)