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Supplements

vitamin B6

What Is It?
Health Benefits

Forms

Recommended Intake

If You Get Too Little

If You Get Too Much
General Dosage Information
Guidelines for Use

General Interaction

Cautions
References
Evidence Based Rating Scale

 

What Is It?

Day by day, there's probably no nutrient as actively involved in keeping the body running smoothly as Vitamin B6. Technically an umbrella term used to describe three B vitamins—pyridoxine, pyridoxal, and pyridoxamine—vitamin B6 partakes in no fewer than 100 chemical reactions throughout the body. Following metabolism in the liver, it becomes pyridoxal 5’ phosphate (P-5-P), which is also available as a supplement. It functions primarily as a coenzyme, working along with other enzymes to speed up chemical reactions in cells.

Incredibly, government surveys indicate that one-quarter of adults are deficient in this key nutrient. (1) The elderly, pregnant or nursing women, oral contraceptive users, and smokers are particularly at risk for a deficiency. A vitamin B6 deficiency in adults can affect the peripheral nerves, skin, mucous membranes, and the hematopoiesis system (responsible for the formation of blood cells), and in children can also affect the central nervous system. (2)

Many foods, including whole grains, legumes, vegetables, liver, meat and eggs, contain rich stores of vitamin B6. But to counter a deficiency or to treat specific disorders, supplements have proven effective. (2)

Health Benefits

A workhorse, vitamin B6 helps manufacture the building blocks of proteins known as Amino acids. It also takes part in producing brain neurotransmitters (chemical messengers) such as Serotonin, in releasing energy stored in cells, and in manufacturing red blood cells. Vitamin B6 also helps to keep hormones in balance and the immune system functioning properly.

Taken as part of a vitamin B-complex supplement, vitamin B6 may help to protect against heart disease and a host of other disorders. For example, in concert with folic acid and vitamin B12, it aids the body in processing Homocysteine, an amino acid-like compound that, at elevated levels, is associated with an increased risk for heart disease and other vascular disorders.

Vitamin B complex supplements (which include vitamin B6) may also minimize memory loss associated with the early stages of Alzheimer's disease. Because a deficiency in vitamin B6 may cause sleep problems, taking it along with the B vitamin niacinamide, which reduces anxiety, may provide some relief from insomnia.

Specifically, vitamin B6 (taken alone) may help to:

Ease carpal tunnel syndrome. Conflicting evidence exists regarding the use of vitamin B6 supplements to treat carpal tunnel syndrome. Proponents believe people who suffer from this painful wrist and hand disorder are often deficient in vitamin B6. Supplements, they believe, may not only decrease the Inflammation that causes complications but may also improve circulation to the compromised areas. In addition, proponents believe vitamin B6 may boost the production of the Neurotransmitter GABA (gamma-aminobutyric acid), which helps to control pain. Some studies have supported these claims. (3, 4) However, a large body of reliable research has shown these patients are not generally deficient in vitamin B6 and do not benefit from supplements. (5-20) 

Improve symptoms of premenstrual syndrome (PMS) and breast pain. Some women find that taking vitamin B6 supplements eases PMS symptoms. This is particularly true for women who suffer from severe breast pain around the time that PMS symptoms occur. The nutrient appears to help by assisting the liver in its effort to wash excess estrogen from the body. In addition, B6 raises levels of the Hormone progesterone and assists in the manufacture of serotonin, a neurotransmitter that enhances mood. A 1999 review of nine trials including 940 patients with PMS found that vitamin B6 in doses of up to 100 mg per day were effective in treating symptoms of PMS, including premenstrual depression. (21) A 2000 study of 44 women with PMS showed that daily supplementation with 50 to 100 mg of vitamin B6 modestly improved symptoms, such as breast pain and tenderness, and premenstrual depression; and taking 50 mg of vitamin B6 plus 200 mg of magnesium oxide daily seemed to relieve anxiety related to PMS. (22) In a 2009 systematic review of randomized, controlled trials involving 62 herbs, vitamins and minerals used to treat PMS, vitamin B6 was one of only ten such treatments identified as effective in relieving symptoms. However, the trials involving vitamin B6 were deemed to be of low quality. Further randomized, controlled trials are needed. (23) 

Prevent recurring kidney stones. Vitamin B6 and magnesium are key nutrients for preventing the formation of calcium oxalate stones, by far the most common kind. Magnesium reduces calcium absorption and lowers urinary oxalate. Stone formation has been shown to be associated with a deficiency of both vitamin B6 and magnesium. Some evidence indicates that taking vitamin B6 alone or in combination with magnesium may help to decrease urinary output of oxalate in people with type I primary hyperoxaluria, a condition that often leads to the formation of this kind of kidney stone. (24-27) Preliminary evidence also indicates that women with higher levels of vitamin B6 may have a reduced risk of developing kidney stones. (28) However, the same association has not been found to be true for men. (29) 

Prevent lung cancer. Preliminary evidence indicates that male smokers who take vitamin B6 prophylactically may reduce the risk of developing lung cancer. In a prospective study involving a cohort of 300 men, those with higher levels of vitamin B6 had a significantly lower risk of developing lung cancer than men with lower levels of vitamin B6. (30) A study of 50 stage III and IV lung cancer patients found those with higher levels of vitamin B6 had reduced red blood cell counts. (31) However, a 2009 combined analysis of two randomized, controlled trials evaluated cancer outcomes and mortality in 1705 patients given vitamin B6 as part of a study on ischemic heart disease. The studies found no correlation between and incidence of cancer. (32)  

Treat ADHD. The B vitamins are believed to help promote nervous system health, an important factor in treating the symptoms of attention deficit disorder (ADHD). In one small study done in the 1970s, vitamin B6 was more effective than Ritalin in relieving symptoms of ADHD in children. (33, 34) However, in conflicting research using megadose pyridoxine in combination with other vitamins, there was no effect on ADHD symptoms. (35) No more recent studies have been carried out.  

Combat depression. Because it is essential for the production of neurotransmitters in the brain (especially serotonin), vitamin B6 may be of value in treating depression. (36) Studies have shown that up to 30% of people struggling with depression may have a deficiency of this nutrient. (37-39) Low vitamin B6 levels have also been linked to stress and anxiety. In a preliminary study of men who were members of a bereavement group, those with low levels of vitamin B6 were more anxious and distressed than those with adequate levels of the nutrient. (40) More research is needed.  

Fight asthma. According to various studies, vitamin B6 may play a role in the treatment of some asthma sufferers. Older studies suggest that some children with severe asthma have deficient metabolism of tryptophan, which is vitamin B6 dependent.  (41) Also, the prescription drug theophylline depresses natural levels of the vitamin B6 analog known as pyridoxal-5-phosphate (P-5-P), and supplementation is recommended. (42-44) Some conflicting studies indicate patients, in general, don't seem to benefit from vitamin B6 supplementation in doses up to 300 mg daily. (45)  

Prevent diabetic nerve damage (neuropathy). People with diabetes are at risk of developing nerve damage. Supplemental vitamin B6 may guard against this complication. Some research shows that taking pyridoxine daily can help to improve symptoms. (46-48) In a 1992 open, multi-center observational study 234 doctors evaluated 1,149 patients with conditions of the nervous system, such as neuropathy. After three weeks of treatment with a vitamin B preparation (Neurotrat forte), 69% of patients reported improvements in pain, and researchers noted a clear improvement in overall symptoms. (46) However, conflicting evidence exists. (49, 50) More research is needed. 

Prevent heart disease. Some preliminary evidence indicates that inadequate vitamin B6 levels may contribute to the development of heart disease. (51-54) Vitamin B6 deficiency allows levels of plasma homocysteine to rise, which has been associated with increased risk for atherosclerosis and myocardial infarction. (55) In a 2008 prospective cohort study involving 40,803 healthy subjects aged 40-59, increased dietary intake of vitamin B6 was associated with a reduced risk of coronary heart disease. (56) However, conflicting evidence exists. A seven-year study published in the Journal of the American Medical Association involving more than 3,000 patients found that taking 40 mg of vitamin B6 supplementation daily did not affect mortality or the incidence of heart disease. (57) And a 2009 Cochrane Database review of trials found no evidence to support the use of homocysteine-lowering interventions, such as vitamin B6 supplementation, to prevent cardiovascular events or heart disease. (58)  And more recently, in a randomized controlled study, diabetics with nephropathy (kidney disease) took a combination of 25 mg of vitamin B6, 2.5 mg of folic acid, and 1 mg of vitamin B12 or placebo. In this study, kidney function worsened more rapidly in the B vitamin group, and they also had an increased risk of heart attack, stroke, heart surgery, or of dying within three years of the study start. (68) The researchers suggested that the pre-existing kidney disease may have compromised excretion of the vitamins, which normally occurs through the kidneys, allowing the vitamins to reach toxic levels.

Reduce nausea and vomiting during pregnancy. Several studies have shown that taking a daily dose of 25 mg of vitamin B6 every eight hours helps relieve morning sickness (nausea and vomiting) during pregnancy. Supplementation has been shown to be particularly effective against more severe cases of nausea. (59, 60) The American College of Obstetrics and Gynecology recommends vitamin B6 as a first-line treatment for pregnancy-induced nausea and vomiting. (61)  

Slow the progression of Parkinson's disease. People with this disease have decreased levels of dopamine, a brain chemical that transmits impulses from nerve to nerve. They are also often deficient in vitamin B6. Interestingly, supplements of the vitamin work to increase the production of dopamine. Although a 2006 review of studies found inconclusive results regarding the effects of vitamin B6 on neurocognitive disorders, such as Parkinson's disease (PD) and Alzheimer's disease, there is some favorable evidence. (62) That same year, results were published from the Rotterdam Study, a prospective, population-based cohort study evaluating dietary intake of various B vitamins and the risk of PD. The results showed that a higher intake of vitamin B6 was associated with a significantly decreased risk of PD. (63) A 2010 case-study of 249 patients with PD found similar results: a low intake of vitamin B6 was associated with an increased risk of PD. (64) More research is needed.  

Treat recurrent seizures in newborns. Certain types of recurring seizures in newborns may be responsive to high doses of intravenous pyridoxine. These may result from genetic pyridoxine dependence, use of high doses of vitamin B6 in pregnancy, or infections. (65-67) 

Forms

  • tablet
  • liquid
  • capsule
  • injectable

Recommended Intake

The RDA for vitamin B6 is 1.3 mg a day for men and women under age 50. For those over 50, the RDA is 1.7 mg for men and 1.5 mg for women.

If You Get Too Little

Mild deficiencies of vitamin B6 can cause increased levels of the amino acid homocysteine, raising the risk of heart and vascular diseases. Severe deficiency is rare. When it occurs, symptoms can include skin disorders such as acne, dermatitis, and mouth sores. Neurological signs of a severe deficiency include insomnia, depression, and, in extreme cases, seizures.

If You Get Too Much

No adverse reactions have been reported with high intakes of vitamin B6 from foods. When taking supplements, even long-term daily doses up to 100 mg are safe. However, in rare cases, taking 200 to 300 mg daily over time has resulted in nerve damage with associated numbness, weakness, and loss of function in the extremities. This serious consequence is more likely to occur when doses of more than 1,000 mg are consumed daily for lengthy periods (two months or more) or with total consumption of 1000 gms. Fortunately, nerve damage is reversible once the vitamin is discontinued.

General Dosage Information

Special tips: Vitamin B6 supplements are available as pyridoxine hydrochloride or pyridoxal-5-phosphate (P-5-P). While both forms will fulfill daily requirements for vitamin B6, P-5-P may be the optimal choice because it appears to be more easily absorbed.

In addition to being available as a single supplement, vitamin B6 is commonly contained in multivitamin and vitamin B complex products. These products supply more than the RDA for vitamin B6, and some may even provide the commonly recommended maximum daily intake of 50 mg. Higher doses are sometimes needed for specific ailments, however.  

For carpal tunnel syndrome: Taking 100 mg three times a day for two weeks, then reducing the dose to 50 mg three times a day has been used. Many sufferers find that vitamin B6 in the form of P-5-P works best for this disorder. 

  • For PMS: 50 to 100 mg daily has been used. For premenstrual breast pain: Take l00 mg twice a day during the week before menses are expected.

  • For kidney stones: 2 to 200 mg daily has been used for primary hyperoxaluria; 10 mg pyridoxine in combination with 300 mg magnesium has been used to prevent kidney stones.

  • For lung cancer prevention: The daily recommended allowances vary by age. Consult a doctor for appropriate dosage.

  • For ADHD: 300 mg daily or larger dosages ranging from 500 mg to 2 g daily have been used.

  • For depression: 50 to 200 mg daily has been used.

  • For asthma: Up to 300 mg daily has been used, but with no proven benefit.

  • For Diabetic neuropathy: 50 mg pyridoxine plus 25 mg thiamine daily has been used.  Do not use is there is co-existing diabetic nephropathy.

  • For Heart disease prevention: 40 mg daily has been used, but with no proven benefit.

  • For Morning sickness: 25 mg every eight hours, as needed, is recommended. Be sure to inform you maternity care provider.

  • For Parkinson's Disease: 400 mg daily has been used. 

Be sure to check out our Dosage Recommendations Chart for vitamin B6, which lists therapeutic dosages for specific ailments at a glance.

Guidelines for Use

For optimum absorption, take no more than 100 mg of vitamin B6 at a time.

General Interaction

The medications phenobarbital and phenytoin used in the treatment of epilepsy are metabolized more quickly and likely to be less effective at doses of 200mg/day. High doses of , vitamin B6 should be avoided when taking these drugs. 

When the prescription drug levodopa (L-dopa) is used as a single agent for Parkinson’s Disease, vitamin B6 supplements can decrease the drug’s efficacy due to more rapid metabolism. Consult a doctor for guidance if on this medication.  

A number of drugs are known to cause increased metabolism of vitamin B6  that could lower levels and result in deficiency. These include: oral contraceptives and other hormone replacement therapy, cycloserine, furosemide, hydralazine, isoniazid, penicillamine, and theophylline.  

Note: For information on interactions with specific generic drugs, see our WholeHealthMD Drug-Nutrient Interactions Chart.

Cautions

Taking high doses of this vitamin (more than 200 mg daily) over the long term may cause nerve damage. 

If taking vitamin B6 for nerve pain and any new numbness or tingling develops, stop taking the supplement and consult a doctor.

References 

1. Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. Washington, DC: National Academy Press; 1998.
2. McKevoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
3. Fuhr JE, Farrow A, Nelson HS Jr. Vitamin B6 levels in patients with carpal tunnel syndrome. Arch Surg 1989;124:1329-30.
4. Head KA. Peripheral neuropathy: Pathogenic mechanisms and alternative therapies. Altern Med Rev 2006;11:294-329.
5. Ellis JM, Kishi T, Azuma J, Folkers K. Vitamin B6 deficiency in patients with a clinical syndrome including the carpal tunnel defect. Biochemical and clinical response to therapy with pyridoxine. Res Commun Chem Pathol Pharmacol 1976;13:743-57.
6. Ellis JM, Azuma J, Watanabe T, et al.
Survey and new data on treatment with pyridoxine of patients having a clinical syndrome including the carpal tunnel and other defects. Res Commun Chem Pathol Pharmacol 1977;17:165-77.
7. Folkers K, Ellis J, Watanabe T, et al. Biochemical evidence for a deficiency of vitamin B6 in the carpal tunnel syndrome based on a crossover clinical study. Proc Natl Acad Sci U S A 1978;75:3410-2.
8. Ellis J, Folkers K, Watanabe T, et al. Clinical results of a cross-over treatment with pyridoxine and placebo of the carpal tunnel syndrome. Am J Clin Nutr 1979;32:2040-6.
9. Ellis J, Folkers K, Levy M, et al. Therapy with vitamin B6 with and without surgery for treatment of patients having the idiopathic carpal tunnel syndrome. Res Commun Chem Pathol Pharmacol 1981;33:331-44.
10. Ellis JM, Folkers K, Levy M, et al. Response of vitamin B-6 deficiency and the carpal tunnel syndrome to pyridoxine.
Proc Natl Acad Sci U S A 1982;79:7494-8.

11. Byers CM, DeLisa JA, Frankel DL, Kraft GH.
Pyridoxine metabolism in carpal tunnel syndrome with and without peripheral neuropathy. Arch Phys Med Rehabil 1984;65:712-6.

12. Smith GP, Rudge PJ, Peters TJ. Biochemical studies of pyridoxal and pyridoxal phosphate status and therapeutic trial of pyridoxine in patients with carpal tunnel syndrome.
Ann Neurol 1984;15:104-7.
13. Stransky M, Rubin A, Lava NS, Lazaro RP. Treatment of carpal tunnel syndrome with vitamin B6: a double-blind study
Date Published: 04/19/2005

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