Vitamin B6
Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and added to others. In its coenzyme forms it performs a wide variety of functions in the body and is extremely versatile, with involvement in more than 100 enzyme reactions, mostly concerned with protein metabolism. It also plays a role in cognitive development through the biosynthesis of neurotransmitters. End-stage renal diseases, chronic renal insufficiency, and other kidney diseases can cause vitamin B6 deficiency, and some medications, such as antiepileptic drugs, can lead to deficiency over time. In infants, vitamin B6 deficiency causes irritability, abnormally acute hearing, and convulsive seizures. People with alcohol dependence might benefit from pyridoxine supplementation.
Where to get it
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Active compounds & mechanisms
Key compounds: Pyridoxine
Research & evidence
Strong support Some support Weak or no supportColours show how well the sources back each point. The reason is next to each one.
Although vitamin B6 shows promise for alleviating PMS symptoms, more research is needed before drawing firm conclusions.
Limited evidenceSome support. The source hedges (“may” or “associated with”)
Study details
NIH ODS says: "Although vitamin B6 shows promise for alleviating PMS symptoms, more research is needed before drawing firm conclusions."
Source: NIH ODS, Vitamin B6 — Health Professional Fact Sheet (Updated June 16, 2023), Vitamin B6 and Health: Premenstrual syndrome View source
Prospective studies on vitamin B6 supplements to treat morning sickness have had mixed results.
Mixed evidenceSome support. Results are mixed
Study details
NIH ODS says: "Prospective studies on vitamin B6 supplements to treat morning sickness have had mixed results."
Source: NIH ODS, Vitamin B6 — Health Professional Fact Sheet (Updated June 16, 2023), Vitamin B6 and Health: Nausea and vomiting in pregnancy View source
Some research has associated low plasma vitamin B6 concentrations with an increased risk of certain kinds of cancer.
Limited evidenceSome support. The source hedges (“may” or “associated with”)
Study details
NIH ODS says: "Some research has associated low plasma vitamin B6 concentrations with an increased risk of certain kinds of cancer"
Source: NIH ODS, Vitamin B6 — Health Professional Fact Sheet (Updated June 16, 2023), Vitamin B6 and Health: Cancer View source
Poor vitamin B6 status has been hypothesized to play a role in the cognitive decline that some older adults experience.
Limited evidenceSome support. The source hedges (“may” or “associated with”)
Study details
NIH ODS says: "Poor vitamin B6 status has been hypothesized to play a role in the cognitive decline that some older adults experience"
Source: NIH ODS, Vitamin B6 — Health Professional Fact Sheet (Updated June 16, 2023), Vitamin B6 and Health: Cognitive function View source
Dosage
| Form | Amount |
|---|---|
| Any form | Recommended daily amounts for adults: 1.3 mg for ages 19 to 50; 1.7 mg (men) and 1.5 mg (women) for ages 51 and older; 1.9 mg during pregnancy and 2.0 mg during lactation. The upper limit is 100 mg a day for adults. |
Side effects
Well documented Reported (case reports, anecdotal or one study) None reportedThe circle shows how well documented an effect is, not how serious it is. A rarely reported effect can still be serious, so always read ‘When to stop’.
| Effect | Frequency | When to stop |
|---|---|---|
| Peripheral neuropathy (numbness or tingling in hands and feet) at very high dosesWell documentedListed plainly by NIH, MSK or LiverTox | Occurs with chronic high-dose intake, typically above 100 mg/day | Stop supplementing and consult a doctor if numbness or tingling develops. |
| Nausea or stomach upsetReportedCase reports only | Uncommon at recommended doses; more likely on an empty stomach | Stop and talk to a doctor if you notice any unexpected or concerning symptoms. |
Safety & interactions
Safety
High intakes of vitamin B6 from food sources have not been reported to cause adverse effects. The upper limits for vitamin B6 apply to both food and supplement intakes. The upper limit is 100 mg a day for adults, and it is lower for children and adolescents based on body size. The upper limits do not apply to individuals receiving vitamin B6 for medical treatment.
Contraindications
No specific contraindications are listed by our sources. If you take cycloserine, levetiracetam, theophylline or another antiepileptic drug, see Drug interactions.
Drug interactions
NIH ODS lists cycloserine (Seromycin), a broad-spectrum antibiotic used to treat tuberculosis, in its vitamin B6 drug interactions section. Our sources don't describe the effect.
NIH ODS lists levetiracetam (Keppra), an antiepileptic medication with behavioral side effects that include irritability, in its vitamin B6 drug interactions section. Our sources don't describe the effect.
NIH ODS lists theophylline, which can prevent or treat shortness of breath, in its vitamin B6 drug interactions section. Our sources don't describe the effect.
NIH ODS says some medications, such as antiepileptic drugs, can lead to vitamin B6 deficiency over time.
Established: stated plainly by an authoritative source. Documented: supported by case reports or trial data. Theoretical: based on mechanism, animal data, or a cautious listing. Always check with your pharmacist or prescriber.
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