Vitamin B6 (Pyridoxine)
Requirements:
- RDA:
2 mg. - 2.2 mg.
Pregnancy/Lactation: 2.6 mg. - 2.7 mg.
- Daily Optimal Intake:
50 mg. for females
35 mg. for males
Supplement Forms:
- Pyridoxine 5 phosphate (the active form of vitamin B6) -
better absorbed
- Pyridoxine hydrochloride - most commonly available
Labs:
- Erythrocyte Glutamate Oxaloacetic Transaminase Test (EGOT
Test)
- Tryptophan Load Test
Food Sources:
- 100% bran cereal 1 cup (2.1 mg.)
- 40% bran flakes cereal 1 cup (0.80 mg.)
- Avocado 1 med. (0.56 mg.)
- Banana 1 med. (0.66 mg.)
- Beef liver 3 oz. (0.47 mg.)
- Chicken, light meat without skin 3 oz. (0.51 mg.)
- Pork loin chop broiled 3 oz. (0.78 mg.)
- Salmon, raw 3 oz. (0.63 mg.)
- Sunflower seeds 1/4 cup (0.45 mg.)
- Tomato juice 1 cup (0.47 mg.)
- Trout - rainbow or steelhead, raw 3 oz. (0.45 mg.)
- Turkey, light meat without skin 3 oz. (0.48 mg.)
- Watermelon 1 slice (0.69 mg.)
Signs and Symptoms of Deficiency:
- Abnormal head movements
- Ataxia
- Convulsions
- Depression
- Hyperacusis
- Hyperirritability
- Mucous membrane lesions
- Nausea
- Peripheral neuritis
- Seborrheic dermatitis
- Vomiting
Causes of Deficiency:
- Aging
- Alcohol
- Antioxidants in the petroleum industry
- Birth control pills
- Celiac disease
- Crohn's disease
- Hydrazine compounds
- Hypoacidity (acid is necessary for vitamin B6 absorption)
- L-canavanine compound - found in alfalfa
- Maleica hydrazide - a plant growth regulator and
herbicide
- Monoamine oxidase inhibitors, isoniazid, theophyline and other
anti asthma medications
- PCB's (polychlorinated biphenols) - have been found in 99% of
all Americans tested
- Penicillamine
- Peroxides and free radicals
- Plating materials and antitarnish agents used in metal
manufacturing
- Pregnancy
- Tartrazine (yellow dye #5)
- Tobacco smoke
Adverse Effects and Toxicity:
- 2 - 5 gm. over a few months may result in numbness and
tingling in the extremities - symptoms usually disappear after B6
is discontinued
- Doses larger than 50 mg. per day may suppress lactation
- Doses of 500 mg. per day or more for extended periods of time
have been reported to cause sensory neuropathy in a stocking-glove
distribution
- Lower doses may cause insomnia or anxiety which may be
prevented by co-administration of magnesium
Drug/Nutrient Interaction:
- Vitamin B6 converts L-Dopa into dopamine outside the blood
brain barrier, decreasing the therapeutic of leva-dopa
- Large doses may increase the need for magnesium, zinc,
essential fatty acids and other B vitamins
- May prevent depression secondary to exogenous estrogens
- Sinemet (L-Dopa and Carbidopa) - synergistic effect
- Oral contraceptives deplete vitamin B6
- Cycloserine limits vitamin B6 availability
- Vitamin B6 (500 mg) protects against elevation of cholesterol by disulfiram
- Oral estrogens decrease optimal absorption of vitamin B6
- Ethionamide causes vitamin B6 deficiency
- Hydralazine antagonizes vitamin B6 and causes deficiency
- Hydrazine decreases vitamin B6 absorption
- Thiosemicarbizide causes vitamin B6 deficiency
- Vitamin B6 decreases neurological symptoms caused from prolonged theophylline usage
- Leva-dopa decreases bioavailability of vitamin B6
- Penicillamine compromises the biological activity of vitamin B6
- Progesterone lowers biological levels of vitamin B6
- Tetracycline decreases absorption of vitamin B6
- Theophylline causes a pyridoxal 5-phosphate deficiency but does not alter serum levels of vitamin B6
- Vitamin B6 decreases neurological symptoms from prolonged theophylline usage
- Pyrazinamide causes pyridoxine deficiency
- Isoniazid causes pyridoxine deficiency
Biochemical Functions:
- Deamination - removal of amino groups from certain amino acids
for energy
- Decarboxylation - removal of COOH groups from certain amino
acids to form another compound
- Desulfuration - transfer sulfhydryl group (HS) from one amino
acid methionine to another, serine, to form cysteine
- Promotes release of glycogen from liver and muscle as
glucose-1-phosphate
- Required for formation of alpha aminolevulinic acid (precursor
of heme in hemoglobin)
- Required for formation of sphygolipids involved in development
of myelin sheath
- Required for series 1 prostaglandins (PGE 1) formation from
linoleic acid
- Required for synthesis of intrinsic factor
- Required for synthesis of neurotransmitters serotonin,
norepinephrine, histamine
- Transamination - transfer of NH2 to other amino acids
Clinical Indications:
Copyright 1998 - 2008 by L. Vicky Crouse, ND and James S. Reiley, ND. All rights reserved (ISSN 1527-0661).