Vitamin B6
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| Vitamin
B6 |
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Vitamin B6 (pyridoxine) is required for the synthesis of the neurotransmitters
serotonin and norepinephrine, and for myelin formation.
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Pyridoxine deficiency in adults principally affects the peripheral nerves,
skin, mucous membranes, and the blood cell system. In children, the central
nervous system (CNS) is also affected. Deficiency can occur in people with
uremia, alcoholism, cirrhosis, hyperthyroidism, malabsorption syndromes,
congestive heart failure (CHF), and in those taking certain medications.
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Mild deficiency of vitamin B6 is common. Major sources of vitamin B6 include:
cereal grains, legumes, vegetables (carrots, spinach, peas), potatoes, milk,
cheese, eggs, fish, liver, meat, and flour.
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Pyridoxine is frequently used in combination with other B vitamins in vitamin
B complex formulations.
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2-Methyl-3-hydroxy-4,5-dihydroxymethylpyridine,
5-hydroxy-6-methyl-3,4-pyridinedimethanol [65-23-6], Adermine Hydrochloride, B
Complex Vitamin, B6, B (6), Bio Zinc, Vicotrat, Beesix, Benadon, Bexivit,
Bonadon N, Hexobion 100, Naturetime B6, Pyridoxal, Pyridoxal Phosphate,
Pyridoxal-5-Phosphate, Pyridoxamine, Pyridoxine HCl, Pyridoxine Hydrochloride,
Pyroxin, Rodex, Vita-Valu, Vitabee 6, Vitamin B-6.
These uses have been tested in humans or animals. Safety
and effectiveness have not always been proven. Some of these conditions are
potentially serious, and should be evaluated by a qualified healthcare provider.
| Uses based on scientific evidence |
Grade* |
| Hereditary sideroblastic anemia
Pyridoxine supplements are effective for treating hereditary
sideroblastic anemia under the supervision of a qualified healthcare
provider.
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A |
| Preventing adverse effects in people taking
cycloserine (Seromycin®)
Cycloserine is a prescription antibiotic that may cause anemia,
peripheral neuritis or seizures by acting as a pyridoxine antagonist or
increasing excretion of pyridoxine. Requirements for pyridoxine may be
increased in patients receiving cycloserine. Pyridoxine may be
recommended by a healthcare provider to prevent these adverse effects.
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A |
| Pyridoxine deficiency/ neuritis
Pyridoxine supplements are effective for preventing and treating
pyridoxine deficiency and neuritis due to inadequate dietary intake,
certain disease states, or deficiency induced by drugs such as isoniazid
(INH) or penicillamine. Dietary supplements should be taken under the
guidance of a qualified healthcare provider.
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A |
| Pyridoxine-dependent seizures in newborns
Pyridoxine-dependent seizures in newborns can result from use of
high-dose pyridoxine in pregnant mothers or from genetic (autosomal
recessive) pyridoxine dependency. Refractory seizures in newborns that
are caused by pyridoxine dependence may be controlled quickly with
intravenous administration of pyridoxine by a qualified healthcare
provider.
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A |
| Akathisia (movement disorder)
Some prescription drugs called neuroleptics, which are used in
psychiatric conditions, may cause movement disorders as an unwanted side
effect. Vitamin B6 has been studied for treatment of acute neuroleptic-induced
akathisia (NIA) in schizophrenic and schizoaffective disorder patients.
Preliminary results indicate that high doses of vitamin B6 may be useful
additions to the available treatments for NIA, perhaps due to its
combined effects on various neurotransmitter systems. Further research
is needed to confirm these results.
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C |
| Angioplasty
There are conflicting findings about the potential benefit or harm of
taking folic acid plus vitamin B6 and vitamin B12 following angioplasty.
Further research is needed before a recommendation can be made.
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C |
| Asthma
Preliminary research suggests that children with severe asthma might
have inadequate pyridoxine status. Theophylline, a prescription drug
used to help manage asthma, seems to lower pyridoxine levels. Studies of
pyridoxine supplementation in asthma patients taking theophylline yield
conflicting results. Further research is needed before a conclusion can
be drawn.
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C |
| Attention deficit-hyperactivity disorder (ADHD)
Some research suggests that pyridoxine supplementation alone or in
combination with high doses of other B vitamins might help ADHD. Other
studies show no benefit. Further research is needed before a conclusion
can be drawn.
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C |
| Birth outcomes
Studies of birth outcomes with vitamin B6 supplementation during
pregnancy yield mixed results. Further well-designed clinical trials
might be helpful in this area.
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C |
| Cardiovascular disease / hyperhomocysteinemia
High homocysteine levels in the blood (hyperhomocysteinemia) are a risk
factor for cardiovascular disease, blood clotting abnormalities,
myocardial infarction, and ischemic stroke. Taking pyridoxine
supplements alone or in combination with folic acid has been shown to be
effective for lowering homocysteine levels. However, it is not clear if
lowering homocysteine levels results in reduced cardiovascular morbidity
and mortality. Until definitive data is available, the current
recommendation is screening of 40 year-old men and 50 year-old women for
hyperhomocysteinemia.Decreased pyridoxine concentrations are also
associated with increased plasma levels of C-reactive protein (CRP). CRP
is an indicator of inflammation that is associated with increased
cardiovascular morbidity in epidemiologic studies.Investigation of more
renal transplant recipients undergoing longer treatment with Vitamin B6
is needed as study results conflict.
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C |
| Carpal tunnel syndrome
Preliminary data suggests that large doses of vitamin B6 may be helpful
for carpal tunnel syndrome. Well-designed clinical trials are needed
before a firm conclusion can be drawn.
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C |
| Depression
Preliminary evidence suggests that because pyridoxine increases
serotonin and GABA levels in the blood, it may benefit people in
dysphoric mental states.Well-designed clinical trials are needed to
confirm potential benefit.
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C |
| Hyperkinetic cerebral dysfunction syndrome
There is preliminary evidence that pyridoxine supplementation might
benefit hyperkinetic children who have low levels of blood serotonin.
Further research is needed to confirm these results.
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C |
| Immune system function
Vitamin B6 is important for immune system function in older individuals.
One study found that the amount of vitamin B6 required to reverse immune
system impairments in elderly people was more than the current
recommended dietary allowance (RDA). Well-designed clinical trials on
vitamin B6 supplementation for this indication are needed before a
recommendation can be made.
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C |
| Kidney stones (nephrolithiasis)
Pyridoxine alone, or taken with magnesium, may decrease urinary oxalate
levels, which can contribute to a certain type of kidney stones. Higher
pyridoxine intake has been associated with decreased risk of kidney
stone formation in women but not in men with no history of stone
formation. Benefit has not been proven in other types of kidney stones
such as those associated with high urinary calcium, phosphorus, and
creatinine. Further data is needed before a firm conclusion can be
drawn.
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C |
| Lactation suppression
Study results of pyridoxine used to suppress lactation yield mixed
results. Well-designed clinical trials are needed before a firm
conclusion can be drawn.
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C |
| Lung cancer
Epidemiological research suggests that male smokers with higher serum
levels of pyridoxine may have a lower risk of lung cancer. Well-designed
clinical trails of pyridoxine supplementation are needed to confirm
these results and supplementation is not standard therapy at this time.
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C |
| Pregnancy-induced nausea and vomiting
Studies of the use of pyridoxine alone or in combination with other
antinausea treatments in pregnant women yield conflicting results.
Further research is needed before a recommendation can be made.
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C |
| Premenstrual syndrome (PMS)
There is some evidence that taking pyridoxine orally may improve
symptoms of PMS such as breast pain or tenderness (mastalgia) and
PMS-related depression or anxiety in some patients. Further research is
needed before a recommendation can be made.
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C |
| Preventing vitamin B6 deficiency associated with
taking birth control pills
The need for vitamin B6 supplementation in women taking birth control
pills has not been proven although some studies show decreased
pyridoxine levels in these women. Supplementation of B6 should be
approached cautiously since the long-term effect of such therapy is
uncertain.
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C |
| Tardive dyskinesia
Pyridoxine has some antioxidant effects, which theoretically may benefit
patients with tardive dyskinesia. Further research is needed before a
recommendation can be made.
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C |
| Autism
Studies of B6 supplementation alone or in combination with magnesium
have not been shown to benefit autism. Autism should be treated by a
qualified healthcare provider.
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D |
| Stroke reoccurrence
Pyridoxine alone or in combination with B12 and folic acid orally does
not seem to be useful for preventing stroke recurrence.
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D |
*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.
Grading rationale
Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often
have not been thoroughly tested in humans, and safety and effectiveness have
not always been proven. Some of these conditions are potentially serious, and
should be evaluated by a qualified healthcare provider.
Acne, alcohol intoxication, allergies, appetite stimulation, arthritis, cancer
prevention, chorea, conjunctivitis, cystitis, diabetic neuropathy, diuresis,
dizziness, Down syndrome, high cholesterol, improving dream recall, infertility,
menopausal symptoms, migraine headaches, motion sickness, muscle cramps,
mushroom poisoning, night leg cramps, psychosis, radiation sickness, sickle cell
anemia, skin conditions.
The below doses are based on scientific research,
publications, traditional use, or expert opinion. Many herbs and supplements
have not been thoroughly tested, and safety and effectiveness may not be proven.
Brands may be made differently, with variable ingredients, even within the same
brand. The below doses may not apply to all products. You should read product
labels, and discuss doses with a qualified healthcare provider before starting
therapy.
Adults (18 years and older):
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Recommended daily allowances (RDAs) of vitamin B6: Males (19-50 years) 1.3
milligrams; (51 years and older) 1.7 milligrams; females (19-50 years) 1.3
milligrams; (51 years and older) 1.5 milligrams. Some researchers think the
RDA for women 19-50 years should be increased to 1.5-1.7 milligrams per day.
Pregnant women, 1.9 milligrams; and lactating women, 2 milligrams.
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Recommended maximum daily intake of vitamin B6: Adults, pregnant and lactating
women (over 18 years) 100 milligrams. A doctor and pharmacist should be
consulted for dosing in other conditions.
Children (younger than 18 years):
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Recommended daily allowances (RDAs) of vitamin B6: Infants (0-6 months) 0.1
milligrams; (7-12 months) 0.3 milligrams; children (1-3 years) 0.5 milligrams;
(4-8 years) 0.6 milligrams; (9-13 years) 1 milligram; males (14-18 years) 1
milligram per day; females (14-18 years) 1.2 milligrams per day.
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Recommended maximum daily intake of vitamin B6: Children (1-3 years) 30
milligrams; (4-8 years) 40 milligrams; (9-13 years) 60 milligrams. Males,
females, pregnant and lactating females (14-18 years) 80 milligrams.
The U.S. Food and Drug Administration does not strictly
regulate herbs and supplements. There is no guarantee of strength, purity or
safety of products, and effects may vary. You should always read product labels.
If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy. Consult a healthcare provider immediately if you
experience side effects.
Allergies
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Patients should avoid vitamin B6 products if they are sensitive or allergic to
any of their ingredients.
Side Effects and Warnings
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Some individuals seem to be particularly sensitive to vitamin B6 and may have
problems at lower doses. Overall, pyridoxine is generally considered safe in
adults and children when used appropriately at recommended doses. Avoid
excessive dosing.
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Acne, skin reactions, allergic reactions, and photosensitivity have been
reported.
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Nausea, vomiting, abdominal pain, loss of appetite, and increased liver
function test results (serum aspartate transaminase (AST, SGOT)) have been
reported.
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Headache, paresthesia, somnolence, and sensory neuropathy have been reported.
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Breast soreness or enlargement, decreased serum folic acid levels, seizures
after large doses, hypotonia and respiratory distress in infants have also
been reported.
Pregnancy and Breastfeeding
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Pregnancy: Vitamin B6 is likely safe when used orally in doses not exceeding
the recommended dietary allowance (RDA). Vitamin B6 is possibly safe when used
orally and appropriately in amounts exceeding the recommended dietary
allowance. A special sustained-release multi-ingredient product is
FDA-approved for use in pregnancy. However, it should not be used long-term or
without medical supervision and close monitoring or in more excessive doses.
There is some concern that high-dose maternal pyridoxine can cause neonatal
seizures.
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Breastfeeding: Vitamin B6 is likely safe when used orally in doses not
exceeding the recommended dietary allowance (RDA). There is insufficient
reliable information about the safety of pyridoxine when used in higher doses
in lactating women. Because most lactating women do not consume the RDA of
vitamin B6 in their normal diets and do not provide totally breast-fed infants
with the RDA of this vitamin, higher doses of vitamin B6 may be recommended
although benefits have not been well proven.
Most herbs and supplements have not been thoroughly
tested for interactions with other herbs, supplements, drugs, or foods. The
interactions listed below are based on reports in scientific publications,
laboratory experiments, or traditional use. You should always read product
labels. If you have a medical condition, or are taking other drugs, herbs, or
supplements, you should speak with a qualified healthcare provider before
starting a new therapy.
Interactions with Drugs
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Preliminary research suggests that pyridoxine could exacerbate amiodarone (Cordarone®)-induced
photosensitivity. Other research suggests a protective effect. Due to
conflicting information, a firm conclusion cannot be drawn at this time but
monitoring may be warranted.
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Destruction of normal gastrointestinal flora by antibiotics can cause
decreased production of the B vitamins. Clinical significance is unknown.
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Cycloserine is an antibiotic that may cause anemia or peripheral neuritis by
acting as a pyridoxine antagonist or increasing renal excretion of pyridoxine.
Requirements for pyridoxine may be increased in patients receiving cycloserine.
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Use of estrogens and estrogen-containing oral contraceptives can interfere
with pyridoxine metabolism, reducing serum pyridoxine levels. The need for
pyridoxine supplementation has not been adequately studied.
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Hydralazine (Apresoline®) can increase pyridoxine requirements. The need for
pyridoxine supplementation has not been adequately studied.
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Isoniazid (INH, Rifamate®) can increase pyridoxine requirements.
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Pyridoxine enhances the metabolism of levodopa (Sinemet®), reducing its
anti-parkinsonism effects. Carbidopa and levodopa used together may avoid this
interaction.
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Penicillamine (Cuprimine®, Depen®) can increase pyridoxine requirements.
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Preliminary data suggests that pyridoxine can reduce plasma levels of
phenobarbital (Luminal®), possibly by increasing metabolism. Patients taking
phenobarbital should avoid high doses of pyridoxine.
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Preliminary data suggests that pyridoxine can reduce plasma levels of
phenytoin (Dilantin®), possibly by increasing metabolism. Patients taking
phenytoin should avoid high doses of pyridoxine.
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Theophylline (Theo-Dur®), a medication used for asthma, interferes with
pyridoxine metabolism. Study results of supplemental pyridoxine in these
patients are inconclusive.
Interactions with Herbs and Dietary Supplements
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Theoretically, herbs and supplements with estrogen-like activity may interact
with pyridoxine. The need for pyridoxine supplementation has not been
adequately studied.