Evidence

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.

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 (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
A

Anemia

Vitamin B6 has been studied for a genetic disorder called sideroblastic anemia, in which the body does not make enough healthy red blood cells. Vitamin B6 supplements have been found to be effective for treating this condition under the care of a medical professional.
A

Nutrition (vitamin B6 deficiency)

Vitamin B6 supplements are effective for preventing and treating vitamin B6 deficiency and nerve inflammation caused by low intake, certain diseases, or some drugs. Dietary supplements should be taken under the guidance of a medical provider.
A

Preventing adverse effects in people taking cycloserine

Cycloserine is a prescription drug that treats tuberculosis or urinary tract infections. It may cause side effects such as anemia (low amounts of healthy red blood cells in the body), nerve inflammation, or seizures. Vitamin B6 has been found to help prevent these side effects.
A

Pyridoxine-dependent seizures in newborns

High doses of vitamin B6 (pyridoxine) in pregnant mothers or genetic disorders may cause seizures in newborns. These seizures may be controlled quickly by a medical professional injecting pyridoxine into the vein.
B

Premenstrual syndrome (PMS)

There is some evidence that taking pyridoxine by mouth may improve PMS symptoms, such as breast pain, depression, or anxiety in some women. Further research is needed before a conclusion can be made.
C

ADHD

Some research suggests that vitamin B6 supplementation used alone or with other vitamins and minerals may help treat ADHD. However, there is conflicting evidence. Further research is needed before a conclusion can be made.
C

Akathisia (disorder causing restlessness and inability to sit still)

Some anti-psychotic drugs may cause movement disorders, such as akathisia. Early study suggests that high doses of vitamin B6 may be helpful when added to standard treatment for this disorder. Further research is needed to confirm these results.
C

Alzheimer's disease prevention

High blood levels of the amino acid homocysteine may indicate Alzheimer's disease risk. Pyridoxine supplements taken alone or with other B vitamins (folic acid) have been found to be effective for lowering homocysteine levels. However, it is unclear whether lowering homocysteine levels also lowers Alzheimer's disease risk. Further research is needed before a conclusion can be made.
C

Angioplasty (surgery for blocked arteries)

There are conflicting findings to support the use of folic acid, vitamin B6, and vitamin B12 together after angioplasty. Further research is needed before firm conclusions can be made.
C

Anxiety

Evidence is lacking to support the use of vitamin B6 for relieving anxiety. More research is needed in this area.
C

Asthma

Early research suggests that children with severe asthma may have low vitamin B6 levels. Theophylline, an anti-asthma drug, seems to lower vitamin B6 levels. Studies of vitamin B6 supplementation in people taking theophylline for asthma have found conflicting results. Further research is needed before a strong conclusion can be made.
C

Atopic eczema (skin disorder causing itchy, scaly rashes)

Supplementation with vitamin B6 has been studied for the treatment of atopic eczema. Early study has looked at the use of vitamin B6 for eczema symptoms in children, but found a lack of effect. High-quality research is needed to make firm conclusions.
C

Birth outcomes

Studies of birth outcomes in which pregnant mothers were given vitamin B6 supplements have found mixed results. Other research suggests that vitamin B6 supplements during pregnancy may help improve dental health and birth weight of babies. More high-quality study is needed in this area.
C

Breast feeding (reducing breast milk)

Early studies have found conflicting results on the use of vitamin B6 for reducing breast milk. Further research is needed before a firm conclusion can be made.
C

Breast tenderness

Evidence is lacking to support the use of vitamin B6 for breast pain or tenderness. More study is needed in this field.
C

Cancer prevention

Some evidence suggests that vitamin B6 lowers the risk of colon cancer. However, a combination of folic acid, vitamin B6, and vitamin B12 did not appear to decrease the risk of breast cancer. There is some evidence that male smokers with higher blood levels of vitamin B6 may have a lower risk of lung cancer. High-quality research is needed to confirm these results. Supplementation is not standard therapy at this time.
C

Carpal tunnel syndrome

Evidence to support the use of vitamin B6 for carpal tunnel syndrome is currently lacking. Early study suggests that people who have the condition may have lower vitamin B6 levels. More research is needed before a firm conclusion can be made.
C

Central nervous system disorders

Early evidence suggests that vitamin B6 supplementation may benefit children with overactive restlessness and low levels of serotonin, a chemical in the brain. Further research is needed to confirm these results.
C

Cognitive function

Early research suggests that poor cognitive function may be associated with low levels of folate in the blood. However, this effect was lacking with vitamin B6. More study on the effects of vitamin B6 alone is needed.
C

Depression

Early study has looked at the use of vitamin B6 for symptoms of depression. Higher blood levels of the amino acid homocysteine may increase the risk for later depression. More studies are needed to confirm potential benefits.
C

Diabetes

Early research suggests that daily vitamin B6 supplementation may improve blood sugar levels in diabetes associated with pregnancy. High-quality research is needed to confirm these results.
C

Fertility in women

Early research suggests that vitamin B6 supplementation may affect female fertility. Vitamin B6 used with other supplements may improve pregnancy outcome. However, strong evidence to support this effect is currently lacking. Further high-quality research on the effects of vitamin B6 alone is needed.
C

Heart disease (high homocysteine levels)

High blood levels of the amino acid homocysteine may be a risk factor for heart disease, blood clotting disorders, clogged arteries, heart attack, and stroke. Vitamin B6 has been studied in combination with other B vitamins (mainly folic acid) for lowering homocysteine levels. Some studies suggest that folic acid may be more effective than vitamin B6, while others report that vitamin B6 alone may lack effect. More research is needed before firm conclusions can be made on the use of vitamin B6 for heart disease.
C

High blood pressure

Early research suggests that vitamin B6 may lower blood pressure. More research is needed to confirm these results.
C

Immune function

Vitamin B6 is thought to be important for immune system function. Early study found positive effects of vitamin B6 on immune response. More research on vitamin B6 supplementation for this use is needed.
C

Kidney stones (general)

Vitamin B6 taken alone or with magnesium may reduce the risk of certain types of kidney stones. Higher vitamin B6 intake has been linked to a lower risk of developing certain kidney stones in women, but this effect was found to be lacking in men without a history of kidney stones. Further studies are needed before a firm conclusion can be drawn.
C

Kidney stones (calcium oxalate stones)

Vitamin B6 taken with other treatments may help maintain kidney function in people with hyperoxaluria, in which excessive amounts of a compound called oxalate are found in the urine. People who have hyperoxaluria often have a high risk for calcium oxalate stones. High-quality research is needed in this area.
C

McArdle's disease

McArdle's disease is a rare, inherited muscle disease that causes fatigue, painful muscle cramps, and muscle failure. Muscle damage in people with this disease may cause dark urine and vitamin B6 deficiency. Early research found a lack of benefit of vitamin B6 for McArdle's disease. Further research is needed.
C

Menstrual cramps

Early research suggests that vitamin B6 may be effective for relieving menstrual cramps. However, evidence is lacking and further research is needed to confirm these results.
C

Osteoporosis prevention

Evidence is conflicting in support of vitamin B6 for bone protection. More studies are needed before a firm conclusion can be made.
C

Pain from nerve disorders

Supplementing with vitamin B6 has been suggested as a treatment for nerve pain. Further research is needed to form conclusions.
C

Pregnancy-induced nausea and vomiting

Studies have looked at the use of vitamin B6 alone or with other anti-nausea treatments in pregnant women, with conflicting results. Further research is needed before a firm conclusion can be made.
C

Preventing vitamin B6 deficiency associated with taking birth control pills

It is thought that women who take birth control pills may need to take vitamin B6 supplements, although this lacks scientific proof. Women on low-dose birth control taken by mouth may have lower levels of the vitamin. B6 supplementation should be used with caution, since long-term effects are unknown. High-quality research is needed in this area.
C

Seizures (caused by fever)

Early research suggests that vitamin B6 may lack effect on seizures caused by fever. More research is needed to confirm these results.
C

Tardive dyskinesia (disorder causing uncontrolled movements)

Vitamin B6 has been studied for people who have tardive dyskinesia. Early research suggests that vitamin B6 may be of benefit for symptoms of this condition. Further research is needed before a firm conclusion can be made.
C

Vein clots

Early research suggests that low levels of vitamin B6 may be a risk factor for blood clots in the veins. Further study is needed to form conclusions.
D

Autism

Studies on at the use of vitamin B6 alone or with magnesium have found unclear results for the treatment of autism. Further research is needed. Autism should be treated by a qualified medical provider.
D

Stroke prevention

Vitamin B6 alone or with vitamin B12 and folic acid has been found to lack effectiveness in preventing recurrent strokes. Further research is needed to determine the effect of vitamin B6 alone.

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.

Alcohol intoxication, allergies, antioxidant, appetite stimulation, arthritis, bladder inflammation, chorea (uncontrolled movement disorder), diabetic nerve pain, dizziness, Down's syndrome, epilepsy (repeated seizures over time), eye disorders (pink eye), high cholesterol, improving urine flow, infertility, kidney failure, menopause, mental illness, migraine headaches, motion sickness, muscle cramps, neural tube defects, nocturnal leg cramps (leg cramps at night), Parkinson's disease, poisoning, radiation sickness, seizure disorders (brain in state of persistent seizure), sickle cell anemia (abnormal red blood cell shape), skin conditions, sleep enhancement, Tourette's syndrome.

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com