Vitamin B6 (Pyridoxine)
Also Known As: Pyridoxal, Pyridoxamine, Pyridoxine hydrochloride, Pyridoxal-5-phosphate
Vitamin B6, also called pyridoxine, is one of eight water-soluble B vitamins.
The B vitamins help the body to convert carbohydrates into glucose (sugar), which
is "burned" to produce energy. These vitamins, often referred to as the B complex,
are also essential in the metabolism of fats and protein. B complex vitamins also
play an important role in maintaining muscle tone in the gastrointestinal tract
and promoting the health of the nervous system, skin, hair, eyes, mouth, and liver.
Vitamins B12, B6, and B9 (folic acid) work closely together to control blood
levels of the amino acid homocysteine. Elevated levels of this substance appear
to be linked to heart disease. Plus, vitamin B6 is essential for normal brain development
and function, participating in the process of making important brain chemicals called
neurotransmitters.
Pyridoxine is an especially important vitamin for maintaining healthy nerve and
muscle cells and it aids in the production of DNA and RNA, the body's genetic material.
It is necessary for proper absorption of vitamin B12 and for the production of red
blood cells and cells of the immune system. Pyridoxine has also been called the
"woman's vitamin" because it may help relieve symptoms of premenstrual syndrome
(PMS).
In addition to other B complex vitamins, pyridoxine is considered an "anti-stress"
vitamin because it is believed to enhance the activity of the immune system and
improve the body's ability to withstand stressful conditions.
Symptoms of pyridoxine deficiency include muscle weakness, nervousness, irritability,
depression, difficulty concentrating, and short-term memory loss.
Uses
Heart Disease
Low dietary intake of vitamin B6 is associated with higher risk of having heart
disease. This may be related to the fact that vitamin B6, together with vitamin
B9 (folic acid) and vitamin B12, help to keep homocysteine levels under control.
Homocysteine is an amino acid. Elevated levels of this amino acid are associated
with increased risk of heart disease and increased risk of stroke.
The American Heart Association recommends, for most people, that enough of these
important B vitamins be obtained from the diet, rather than taking extra supplements.
Under certain circumstances, however, supplements may be necessary. Such circumstances
include elevated homocysteine levels with known heart disease or strong family history
of heart disease at a young age.
Nausea and Vomiting during pregnancy
A recent review of scientific studies concluded that vitamin B6 may help reduce
the severity of nausea during early pregnancy.
Osteoporosis
Keeping bones healthy throughout life depends on getting sufficient amounts of
specific vitamins and minerals, including phosphorous, magnesium, boron, manganese,
copper, zinc, folate, and vitamins C, K, B6, and B12.
Eating Disorders
Levels of important nutrients are often quite low in those with anorexia or bulimia.
At least 20% of people with anorexia admitted to a hospital for treatment are deficient
in vitamins B2 and B6 (pyridoxine). Some research information suggests that as many
as 33% of those with an eating disorder could be deficient in vitamins B2 and B6.
Dietary changes alone, without additional supplements, can often bring vitamin B
levels back to normal. However, extra B2 and B6 may be required (which will be determined
by your doctor or nutritionist). Plus, B-complex vitamins may help alleviate stress
and reduce symptoms of depression, frequently associated with eating disorders.
Burns
It is especially important for people who have sustained serious burns to obtain
adequate amounts of nutrients in their daily diet. When skin is burned, a substantial
percentage of micronutrients may be lost. This increases the risk for infection,
slows the healing process, prolongs the hospital stay, and even increases the risk
of death. Although it is unclear which micronutrients are most beneficial for people
with burns, many studies suggest that a multivitamin including the B complex vitamins
may aid in the recovery process. Vitamin B6, along with other members of the B complex,
may be of particular importance, given their value in building protein. Protein
is necessary to recover from any kind of an injury. In addition, as stated earlier,
the amount of B complex needed may increase during times of stress.
Depression
Studies suggest that vitamin B9 (folate) may be associated with depression more
than any other nutrient. Between 15% and 38% of people with depression have low
folate levels in their bodies and those with very low levels tend to be the most
depressed. Many healthcare providers start by recommending a multivitamin (MVI)
that contains folate, and then monitoring the homocysteine levels in the blood to
ensure the adequacy of therapy. Elevated homocysteine levels indicate a deficiency
of folate even if the levels of folate in the blood are normal. If the MVI alone
is not enough to lower homocysteine and improve folate function, the provider may
suggest additional folate along with vitamins B6 and B12 to try to bring the homocysteine
levels down, thereby eliminating the functional folate deficiency and, hopefully,
helping to improve feelings of depression.
Premenstrual Syndrome (PMS)
A comprehensive review of studies concluded that vitamin B6 may be more effective
than placebo in improving symptoms of PMS, particularly depression. Most studies
were poorly designed, however. Still, even though the science is not definitive,
many healthcare providers and their female patients report improvement in PMS from
using vitamin B6. Therefore, how well you respond to vitamin B6 may be very individual.
Until more research is completed, talk with your doctor about whether using B6 is
appropriate and safe for you. Then, if taking the vitamin, follow your symptoms
closely. It can take up to 3 months until any change is noticeable.
Diabetes
Preliminary evidence suggests that vitamin B6 may help control blood sugar in
people with diabetes. In a study of people with diabetes, those who received pyridoxine
alpha-ketoglutarate (a form of vitamin B6) for one month experienced significant
reductions in fasting blood sugar levels compared to those who did not receive the
supplement. More research in this area is needed before conclusions can be drawn
about the relationship between vitamin B6 and diabetes.
Human Immunodeficiency Virus (HIV)
Vitamin B6, particularly together with a complete B complex, may help alleviate
the stress associated with having HIV or AIDS.
Attention Deficit/Hyperactive Disorder (ADHD)
Adequate levels of vitamin B6 are required for normal brain development and are
essential for the synthesis of essential brain chemicals including serotonin, dopamine
and norepinephrine. A preliminary study found that pyridoxine was slightly more
effective than methylphenidate (a medication used to treat ADHD) in improving behavior
among hyperactive children. Although intriguing, the results of this study were
not significant and no other studies have been able to confirm these findings. Therefore,
supplementation with vitamin B6 is not considered standard treatment for ADHD.
Rheumatoid Arthritis
Low levels of vitamin B6 have been associated with rheumatoid arthritis. This
may be due to low dietary intake of vitamin B6 and other important nutrients by
people with this joint disorder. Eating a balanced diet, including a complete vitamin
B complex, is a good idea for anyone with a chronic illness, such as rheumatoid
arthritis. It is not known if taking extra vitamin B6 is of any use if you have
arthritis.
Dietary Sources
Good dietary sources of vitamin B6 include chicken, turkey, tuna, salmon, shrimp,
beef liver, lentils, soybeans, nuts, avocados, bananas, carrots, brown rice, bran,
sunflower seeds, wheat germ, and whole-grain flour.
Available Forms
Vitamin B6 can be found in multivitamins (including children's chewable and liquid
drops), B complex vitamins, or can be sold individually. It is available in a variety
of forms including tablets, softgels, and lozenges. Vitamin B6 is also sold under
the names pyridoxal, pyridoxamine, pyridoxine hydrochloride, and pyridoxal-5-phosphate.
How to Take It
People who eat a balanced diet containing good sources of vitamin B6 should be
able to meet the daily requirement without taking a supplement. Vitamin supplements
should always be taken with water, preferably after a meal. As with all medications
and supplements, check with a healthcare provider before giving vitamin B6 supplements
to a child.
Daily recommendations for dietary vitamin B6 are listed below.
Pediatric
Newborns to 6 months: 0.1 mg (adequate intake)
Infants 7 months to 1 year: 0.3 mg (adequate intake)
- Children 1 to 3 years: 0.5 mg (RDA)
- Children 4 to 8 years: 0.6 mg (RDA)
- Children 9 to 13 years: 1 mg (RDA)
- Males 14 to 18 years: 1.3 mg (RDA)
- Females 14 to 18 years: 1.2 mg (RDA)
Adult
- 19 to 50 years: 1.3 mg (RDA)
- Males 51 years and older: 1.7 mg (RDA)
- Females 51 years and older: 1.5 mg (RDA)
- Pregnant females: 1.9 mg (RDA)
- Breastfeeding females: 2.0 mg (RDA)
Prevention of heart disease and lowering of homocysteine levels: 3.0 mg per day.
Nausea and vomiting during early pregnancy: studies on this topic have used 10
mg per day. The amount to use, however, should be determined together with your
obstetrician.
Therapeutic doses for some of the conditions discussed in the Uses section have
ranged from 100 to as high as 1,800 milligrams per day. Using doses higher than
200 mg per day for long periods of time, however, may cause neurologic disorders
(see Precautions).
Precautions
Because of the potential for side effects and interactions with medications,
dietary supplements should be taken only under the supervision of a knowledgeable
healthcare provider.
Vitamin B6 can cause neurological disorders, such as loss of sensation in legs
and imbalance, when taken in high doses (200 mg or more per day) over a long period
of time. Discontinuing high doses usually leads to a complete recovery within 6
months.
There have been extremely rare reports of allergic skin reactions to high doses
of vitamin B6 supplements.
Possible Interactions
If you are currently being treated with any of the following medications, you
should not use vitamin B6 supplements without first talking to your healthcare provider.
Antibiotics, Tetracycline
Vitamin B6 should not be taken at the same time as the antibiotic tetracycline
because it interferes with the absorption and effectiveness of this medication.
Vitamin B6 either alone or in combination with other B vitamins should be taken
at different times from tetracycline. (All vitamin B complex supplements act in
this way and should therefore be taken at different times from tetracycline.)
Antidepressant Medications, Tricyclic
Taking vitamin B6 supplements may improve the effectiveness of certain tricyclic
antidepressants such as nortriptyline, especially in elderly individuals. Other
tricyclic antidepressants include desipramine and imipramine.
On the other hand, another class of antidepressants called monoamine oxidase
inhibitors (MAOIs) may reduce blood levels of vitamin B6. Examples of MAOIs include
phenelzine and tranylcypromine.
Antipsychotic Medications
Preliminary evidence suggest that pyridoxine may prove useful in treating tardive
dyskinesia, a common but frustrating side effect from medications used to treat
schizophrenia. Tardive dyskinesia is marked by involuntary movements of the mouth
and tongue. More research is needed to know if vitamin B6 can help prevent or treat
this side effect.
Tuberculosis Medications
Anti-tuberculosis medications such as isoniazid (INH) and cycloserine (used for
resistant forms of tuberculosis) reduce the levels of vitamin B6 in the blood.
Birth control medications
Birth control medications may reduce blood levels of vitamin B6.
Chemotherapy
Vitamin B6 may reduce certain side effects of 5-fluorouracil and doxorubicin,
two agents used to treat cancer without reducing the effectiveness of the chemotherapy.
Erythropoietin
Erythropoietin therapy used for severe anemia may decrease vitamin B6 levels
in red blood cells. Therefore, vitamin B6 supplementation may be necessary during
erythropoietin therapy.
Hydralazine
Vitamin B6 decreases the effectiveness of hydralazine, a medication used to treat
high blood pressure.
Levodopa
Vitamin B6 reduces the effectiveness of levodopa, a medication used to treat
Parkinson's disease.
Methotrexate
People with rheumatoid arthritis taking this medication often have low levels
of vitamin B6.
Penicillamine
Penicillamine, a medication used in the treatment of rheumatoid arthritis and
Wilson's disease (excessive amounts of copper in the body that can lead to liver
damage) may decrease levels of vitamin B6 in the body.
Phenytoin
Vitamin B6 reduces the effectiveness of phenytoin, a medication used to treat
seizures.
Theophylline
Long-term treatment with theophylline for asthma may reduce blood levels of vitamin
B6.
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Review Date: April 2002
Reviewed By: Participants in the review process include: Ruth DeBusk, RD, PhD,
Editor, Nutrition in Complementary Care, Tallahassee, FL; Jacqueline A. Hart, MD,
Department of Internal Medicine, Newton-Wellesley Hospital, Harvard University and
Senior Medical Editor Integrative Medicine, Boston, MA; Gary Kracoff, RPh (Pediatric
Dosing section February 2001), Johnson Drugs, Natick, Ma; Steven Ottariono, RPh
(Pediatric Dosing section February 2001), Veteran's Administrative Hospital, Londonderry,
NH. All interaction sections have also been reviewed by a team of experts including
Joseph Lamb, MD (July 2000), The Integrative Medicine Works, Alexandria, VA;Enrico
Liva, ND, RPh (August 2000), Vital Nutrients, Middletown, CT; Brian T Sanderoff,
PD, BS in Pharmacy (March 2000), Clinical Assistant Professor, University of Maryland
School of Pharmacy; President, Your Prescription for Health, Owings Mills, MD; Ira
Zunin, MD, MPH, MBA (July 2000), President and Chairman, Hawaii State Consortium
for Integrative Medicine, Honolulu, HI.
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