Vitamin B6, Pyridoxine
Pyridoxine is absorbed in the upper small intestine by simple diffusion. Greater absorption occurs with more acidic environments.
The active form is pyridoxine phosphate, PyrP, which is cofactor for:
L-DOPA -> Dopamine (note: Dopamine -> NE -> EPI)
tryptophan -> niacin (several steps)
linoleic acid -> gamma linoleic acid (note: GLA -> DHGLA -> PGE-1)
homocysteine -> Cystathione-> Cysteine (both steps)
histidine -> histamine
Succinyl CoA -> 2 Amino 3 Keto Adipate (forms Heme)
5-HTP -> Serotonin
transamination - transfer NH2 to amino acids
deamination, desulfuration, decarboxylation
promotes release of glycogen from liver and muscle as glucose-1P
vital for the formation of sphyngolipids involved in myelin sheaths
involved in the synthesis of intrinsic factor
RDA - 2-2.2 mg, pregnancy - 6 mg, lactation - .5 mg
Optimal - men - 35 mg, women - 50 mg
Requirement increased in pregnancy and with estrogen use.
Estrogens may inhibit pyridoxal phosphate in tryptophan metabolism.
tryptophan load test
Erythrocyte Glutamate Oxaloacetic Transaminase Test
contraindicated with L-Dopa treatment for Parkinson's
but not with Cinemet (L-Dopa with carbo-Dopa)
hydrazines (Nardil), Isoniazid, theophylin, BCPs, hydralazine
tartrazine (yellow dye #5), tobacco smoke, some pesticides
bend the fingers at the PIP joint while keeping the DIP joints straight
people with homocysteinuria develop significant atherosclerosis
and severe osteoporosis by age 20
nausea and vomiting
mucus membrane lesions, seborrheic dermatitis
peripheral neuritis, grand mal seizures
asthma - phosphodiesterase inhibitor (similar to theophylin)
MSG sensitivity - cofactor for glutamate -> 2-Keto glutarate
kidney stones - cofactor for oxaloacetate -> aspartate
anemia - cofactor for Succinyl CoA-> Heme
pyridoxine dependant epilepsy - siezures up to 18 months of age
depression, dementia, schizophrenia, ADD - 5-HTP -> Serotonin
carpal tunnel syndrome, rheumatism
diabetic neuropathy - prevents tissue glycosylation
acne - phosphodiesterase inhibitor
seborrheic dermatitis - topically, usually gets worse short-term
lupus - drugs that induce lupus also inhibit B6, 500 mg qd
nausea of pregnancy, toxemia of pregnancy
gestational diabetes - high estrogen impairs tryptophan pathways
which promotes xanthurenic acid production which binds to insulin
autism - large doses reduce difficult behavior patterns
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