MODULE 2: B6, B9, B12

Question 1

Folate is?

Answer 1

B9

Question 2

Cobalamin is?

Answer 2

B12

Question 3

Pyridoxine is?

Answer 3

B6

Question 4

Pantothenic acid is?

Answer 4

B5

Question 5

Thiamin is?

Answer 5

B1

Question 6

Riboflavin is?

Answer 6

B2

Question 7

Niacin is?

Answer 7

B3

Question 8

** Know what the 4 D’s stand for? Vitamin Associated

Answer 8

Dementia
Dermatitis
Diarrhea
Death

Niacin! (B3)

Question 9

Biotin is?

Answer 9

B7

Question 10

** Know what pellegra is; what B vitamins might be associated

Answer 10

Pellegra is SEVERE B3 deficiency - presents as 4 D’s

B6 deficiency might also present with Pellegra

Question 11

** Fate of homocysteine in methylation pathway (what vitamins involved?)

Answer 11

B6! = Homocysteine —> Cystathionine —> Cysteine

B12! = Homocysteine —> Methionine (using methionine synthase) + folate

Question 12

Zinc and folate absorption

Answer 12

Zinc deficiency INHIBITS folate (B9) absorption

Question 13

** Regulation of sodium channels and ACH receptors involves what B vit?

Answer 13

Thiamin/B1

Question 14

** T/F there is more folate in RBCs than is plasma

Answer 14

T

Question 15

**FUNCTION OF FOLATE

Answer 15

Facilitates the transfer of one carbon-groups from one bio molecule to another

Question 16

** Why is SAMe important? (Function)

Answer 16

Important methylating compound (produced by methionine in methylation pathway)

** PRINCIPAL BIOLOGICAL METHYL DONOR

Question 17

** Cysteine, glutamine, and glycine are used to produce?? (Hint: antioxidant)

Answer 17

GLUTATHIONE

Question 18

** Vitamin B12 & Intrinsic Factor relationship

Answer 18

B12 must BIND with IF in order to be absorbed in the small intestine

(Forms a complex and complex binds to receptors in intestinal enterocytes)

Question 19

** Describe absorption of B12/where it takes place

Answer 19

1. B12 released from food
2. Binds to R proteins (found in gastric juice)
3. R protein brings B12 to small intestine
4. B12 binds with INTRINSIC FACTOR (in upper intestine)
5. B12-IF complex binds to enterocyte receptors and B12 is absorbed in **DISTAL small intestine

Question 20

** Know B vitamin involved in Pernicious Anemia

Answer 20

B12

Question 21

** Where is B12 primarily stored in the body?

Answer 21

LIVER

Question 22

** Conversion of homocysteine to methionine requires ?

Answer 22

B12

Question 23

** Metabolism of vitamin B6 to the primary coenzyme form, PLP (pyridoxal phosphate), requires ??

Answer 23

RIBOFLAVIN

Question 24

** Lethargy, depression, hallucinations, muscle pain, scaly/red dermatitis is seen with deficiency in?

Answer 24

BIOTIN (B7)

Question 25

** Fatty acid and cholesterol synthesis - know B vitamin involved

Answer 25

NIACIN

Question 26

** What 3 B vitamins are needed to synthesize fatty acids?

Answer 26

Niacin (B3) Riboflavin (B2) Pantothenic Acid (B5)

Question 27

** B vitamin involved in pernicious anemia?

Answer 27

B12 (caused by not enough IF)

Question 28

** Niacin & toxicity?

Answer 28

Tolerable Upper Limit because of VASODILATORY EFFECTS Those with HYPERLIPIDEMIA should avoid/be careful

Question 29

** Niacin toxicity includes

Answer 29

``` SKIN FLUSHING Rapid heart beat Dizziness GI distress (nausea, abdominal pain) Itching Headache ```

Question 30

** Niacin can be synthesized in the body from?

Answer 30

Tryptophan

Question 31

** Niacin’s use in cholesterol treatment? Blood sugar? Metabolic syndrome?

Answer 31

Niacin: Used to treat high cholesterol (Lower LDL, raise HDL, lower triglycerides) May not be useful as it is also associated with inducing insulin resistance/affecting glucose homeostasis and therefore exacerbating metabolic syndrome

Question 32

** Niacin function in fatty acid/cholesterol synthesis?

Answer 32

Niacin AS NADPH acts as a reducing agent in F.A./cholesterol synthesis

Question 33

** Hexose Monophosphate shunt is????

Answer 33

Pentose Phosphate pathway

Question 34

** Niacin’s relationship to Hexose Monophosphate shunt?

Answer 34

NADPH (Niacin/nicotinamide) produced via the Hexose Monophosphate shunt/Pentose-Phosphate pathway

Question 35

** B12 testing?

Answer 35

Serum B12 ** Methylmalonic acid urine test (If MMA high, B12 low)

Question 36

** B12 deficiency symptoms include:

Answer 36

* * Megaloblastic, macrocytic anemia - Fatigue, pale skin - Shortness of breath - Heart palpitations Neurological - Numbness in extremities - Poor coordination - Abnormal gait - Memory loss - Psychosis - Dementia

Question 37

** RDA for folic acid in women of childbearing age

Answer 37

400 micrograms

Question 38

** Relationship between folic acid and B12 deficiency

Answer 38

Consuming high amounts of folate can MASK B12 deficiency

Question 39

** Digestive enzymes relationship to FOLATE

Answer 39

Folic acid digestion requires CONJUGASE and other enzymes in order to be broken down and absorbed ** Go from poluglutamate form in food —> monoglutamate (to be absorbed)

Question 40

** Best way for accessing long term folate levels?

Answer 40

FIGLU excretion Homocysteine levels! (Elevated H means low B9/12)

Question 41

** What enzyme is the drug methotrexate designed to inhibit?

Answer 41

Inhibits DIHYDROFOLATE REDUCTASE which converts DHF to Tetra hydrofolate

Question 42

** Methyl-Folate Trap hypothesis

Answer 42

Involves SYNERGISTIC RELATIONSHIP b/t B9 & B12 (During synthesis of methionine from homocysteine) adequate B12 is require to transfer methyl group to folate If not enough B12, folate gets “trapped” in unusually form/form needed for DNA synthesis THEREFORE DNA synthesis cannot be accomplished

Question 43

** What vitamin is required to activate B6?

Answer 43

Riboflavin (B2)

Question 44

** Elevated homocysteine means what for B6/9/12?

Answer 44

Elevated H = deficiency B6/9/12

Question 45

** Folate’s function in dividing cells during growth

Answer 45

THF (tetrahydrofolate) involved in DNA synthesis/cell division —> promotes proliferation of all cells (good and bad)

Question 46

** Tetrahydrofolate and cancer/dividing cells

Answer 46

THF involved in cells division/proliferation/DNA synthesis —> THF sometimes blocked in anti-cancer drugs because THF PROMOTES CELLS PROLIFERATION/GROWTH

Question 47

** Absorption of folate from green (leafy) vegetables (eg. FOLATE IN FOOD)

Answer 47

Dietary folate (veggies) require digestion in order to be absorbed Digestion occurs via ENZYMES (Conjugases/carboxypeptidases in brush border) - Brush border enzymes require ZINC & ADEQUATE pH