Vitamin B6, also called pyridoxine, is one of 8 B vitamins. All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy. These B vitamins, often referred to as B-complex vitamins, also help the body metabolize fats and protein. B-complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.
All B vitamins are water soluble, meaning the body does not store them.
Vitamin B6 helps the body make several neurotransmitters, chemicals that carry signals from one nerve cell to another. It is needed for normal brain development and function, and helps the body make the hormones serotonin and norepinephrine, which influence mood, and melatonin, which helps regulate the body clock.
Along with vitamins B12 and B9 (folic acid), B6 helps control levels of homocysteine in the blood. Homocysteine is an amino acid that may be associated with heart disease. Your body needs B6 in order to absorb vitamin B12 and to make red blood cells and cells of the immune system.
It is rare to have a significant deficiency of B6, although studies indicate many people may be mildly deficient, especially children and the elderly. Certain medications can also cause low levels of B6 in the body. Symptoms of serious deficiency include:
- Muscle weakness
- Difficulty concentrating
- Short-term memory loss
It is not clear how vitamin B6 might affect heart disease. People who do not get enough B6 in their diet have a higher risk of heart disease. And B6 plays a role in lowering levels of homocysteine in the blood. High levels of homocysteine appear to be associated with heart disease. But scientists do not know exactly what the relationship is. They also do not know whether lowering levels of homocysteine will reduce your risk of heart disease. Until more is known, the best action is to get enough B6 through food, and to take supplements if your doctor recommends them.
Nausea and vomiting during pregnancy (morning sickness)
Several studies, including one large double-blind, placebo-controlled study, found that a daily dose of 30 mg of B6 may help reduce morning sickness. However, other studies have found no benefit. If you are pregnant, be sure to ask your doctor before taking any supplements, including vitamin B6.
Age-related macular degeneration (AMD)
One large study found that women who took 50 mg of vitamin B6 daily, along with 1,000 mcg of cyanocobalamin (vitamin B12) and 2,500 mcg of folic acid, reduced their risk of developing AMD, an eye disease that can cause vision loss.
Vitamin B6 helps your body make serotonin, a chemical that influences mood. Low levels of serotonin are associated with depression, and some antidepressant medications work by raising levels of serotonin. Some researchers think that vitamin B6 might help reduce symptoms of depression. More research is needed.
Premenstrual syndrome (PMS)
Although some studies show that vitamin B6 may help improve PMS symptoms, most of these studies were poorly designed. Studies that were well designed found no benefit. Until more research is done, talk with your doctor about whether taking B6 is right for you. Some people who believe B6 is effective for PMS say it may take up to 3 months to see a noticeable change.
Carpal tunnel syndrome
Early studies suggested that B6 might help reduce inflammation and symptoms of carpal tunnel syndrome, however, most well-designed studies have found no such link.
Rheumatoid arthritis (RA)
Low levels of vitamin B6 have been associated with RA. Some studies also suggest that people with RA may need more vitamin B6 than healthy people because chronic inflammation may lower B6 levels. Eating a healthy, balanced diet, and taking a multivitamin is a good idea for anyone who has a chronic illness, such as RA. Talk to your doctor before taking B6 supplements.
A few small studies have found that vitamin B6 may improve symptoms of tardive dyskinesia compared to placebo. Tardive dyskinesia is a side effect of long-term use of antipsychotic drugs, and involves involuntary movement of muscles, such as in the tongue, lips, face and jaw, arms, legs, fingers, or toes.
Good food sources of vitamin B6 include:
- Fortified ready-to-eat cereal
- Beef liver
- Brown rice
- Sunflower seeds
- Wheat germ
- Whole-grain flour
Vitamin B6 can be found in multivitamins, including children's chewable and liquid drops, B complex vitamins, or can be sold separately. It is available in a variety of forms, including tablets, soft gels, 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 should meet the daily requirement for vitamin B6 without taking a supplement. As with all medications and supplements, check with a health care provider before giving vitamin B6 supplements to a child.
Daily recommendations for dietary vitamin B6 are:
- Infants, 0 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)
- Boys, 14 to 18 years: 1.3 mg (RDA)
- Girls, 14 to 18 years: 1.2 mg (RDA)
- Men and women, 19 to 50 years: 1.3 mg (RDA)
- Men, 51 years and older: 1.7 mg (RDA)
- Women, 51 years and older: 1.5 mg (RDA)
- Pregnant women: 1.9 mg (RDA)
- Breastfeeding women: 2.0 mg (RDA)
Larger doses have been used in some studies. But you should not take doses above 100 mg per day without a doctor's supervision. Large doses of B6 may cause nerve damage.
You should take dietary supplements only under the supervision of a knowledgeable health care provider because of the potential for side effects and interactions with medications.
Very high doses, 200 mg or more per day, of vitamin B6 can cause neurological disorders, such as loss of feeling in the legs and imbalance. Stopping high doses usually leads to a complete recovery within 6 months.
There have been rare reports of allergic skin reactions to high doses of vitamin B6 supplements.
Other side effects can include:
- Sensitivity to sunlight
- Abdominal pain
- Loss of appetite
If you are being treated with any of the following medications, you should not use vitamin B6 supplements without talking to your health care provider first.
Medicines that reduce levels of B6 in the body. If you take any of these medications, be sure to get enough B6 in your diet:
- Cycloserine (Seromycin), used to treat tuberculosis
- Hydralazine (Apresoline), used to treat high blood pressure
- Isoniazid, used to treat tuberculosis
- Penicillamine, used to treat RA
- Theophylline (TheoDur), used to treat asthma
Antibiotics, tetracycline: All B complex vitamins, including vitamin B6, interfere with the absorption and effectiveness of antibiotic tetracycline. You should take tetracycline at different times from vitamin B6 and other B vitamins.
Antidepressant medications: Taking vitamin B6 supplements may improve the effectiveness of some tricyclic antidepressants such as nortriptyline (Pamelor), especially in elderly people. Other tricyclic antidepressants include amitriptyline (Elavil), desipramine (Norpramin), and imipramine (Tofranil).
On the other hand, antidepressants called monoamine oxidase inhibitors (MAOIs) may reduce blood levels of vitamin B6. Examples of MAOIs include phenelzine (Nardil) and tranylcypromine (Parnate).
Amiodarone (Cordarone): This drug, used to treat an irregular heartbeat, makes your skin more sensitive to sunlight. Taking vitamin B6 along with this medication may increase your risk of sunburn, blistering, or a rash.
Chemotherapy drugs: Vitamin B6 may reduce certain side effects of 5-fluorouracil and doxorubicin, medications used to treat cancer. Talk to your doctor before taking any supplement if you are undergoing chemotherapy.
Erythropoietin (EPO): Erythropoietin therapy, used to treat severe anemia, may decrease vitamin B6 levels in red blood cells.
Levodopa (L-dopa): Vitamin B6 reduces the effectiveness of levodopa, a medication used to treat Parkinson disease. However, it does not seem to have the same effect on the combination of levodopa and carbidopa. Your doctor may be able to determine a dose of B6 that can safely help reduce side effects of levodopa. You should only take vitamin B6 along with levodopa under your doctor's supervision.
Phenytoin (Dilantin): Vitamin B6 makes phenytoin, a medication used to treat seizures, less effective.
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