B6

Question 1

Interaction with tryptophan

Answer 1

Increases serotonin

Antidepressant

Question 2

Comes in 3 forms

Answer 2

Pyridoxine PN (most stable form, found in plants and supplements). Alcohol form.

Pyridoxal PL. Aldehyde form. Animal.
Pyridoxamine PM. Amine form. Animal.

All have 5’ phosphate derivative

Question 3

Schiff base

Answer 3

Binds to AA to make Schiff base.
Active phosphorylated form.

Coenzyme functions.

Question 4

PLP

Answer 4

Liver main site of synthesis. RBC. 10% stored in liver. 80% stored in cell.

PLP food source hydrolyzed by zinc dependent phosphatase prior to uptake. Creates PL.

PL rephosphorylated in cell.

Question 5

PLP Storage

Answer 5

In blood: PLP bound to albumin (protect from phosphatase)

Unphosphorylated passively diffuse.

80% stored in muscle bound to glycogen

In RBC: PLP bound to hemoglobin

Question 6

Interactions with other nutrients

Answer 6

Riboflavin maintains B6

Works with thiamin in Kreb’s cycle.

Question 7

Sources

Answer 7

Chicken, banana, fortified cereal.

Supplement: pyridoxine hydrochloride

Question 8

RDA

Answer 8

1.3 mg

Question 9

Assessment

Answer 9

Direct: plasma >30 nmol/L

Functional: tryptophan load test measures xanthurenic acid excretion (produced in deficiency)

Question 10

Function

Answer 10

Coenzyme.

AA metabolism.

Niacin synthesis.

Glycogen degradation.

Question 11

Deficiency

Answer 11

Depression, cheilosis, anemia.

Can be caused my riboflavin deficiency.
Mg needed as well to convert PN to PLP.

Question 12

Toxicity

Answer 12

100 mg

Neuropathy, impaired reflexes.

Question 13

Therapy/ megadosing

Answer 13

Carpal tunnel, premenstrual, depression, muscle fatigue