Overview
Vitamin B6 (pyridoxine) is a water-soluble vitamin essential for amino acid metabolism, neurotransmitter synthesis, and homocysteine regulation. It acts as a coenzyme in over 100 enzymatic reactions, particularly in the production of serotonin, dopamine, and GABA, which may explain its role in mood regulation. Research suggests that adequate B6 status, often in combination with folate and B12, is associated with reduced homocysteine levels—a biomarker linked to cardiovascular disease, stroke, and depression [1][2]. Observational data indicate a potential inverse relationship between dietary B6 intake and stroke risk, with dose-response effects observed in meta-analyses [1]. In clinical trials, supplementation with B6 (25 mg/day) alongside B12 and folic acid did not significantly improve depression outcomes in older adults receiving antidepressants, though trends favored the intervention [5]. Additionally, a combination of magnesium and vitamin B6 (30 mg/day) demonstrated superior reduction in perceived stress compared to magnesium alone in stressed adults with low magnesium levels [8]. However, evidence for B6 in cancer prevention or treatment remains inconclusive and potentially context-dependent, warranting caution in high-dose use among oncology patients [6].
Dosage Guide
Recommended Daily Allowance
For generally healthy individuals
Therapeutic Doses
For treatment of specific conditions
Upper Intake Limit
Maximum safe daily intake
100 mg— Tolerable upper intake level for adults; long-term intake above this may cause sensory neuropathy
Special Forms
Alternative forms for specific needs
Active form; used in genetic polymorphisms affecting B6 metabolism, neurological conditions, and when gastrointestinal absorption is impaired
Clinical Notes
- High-dose B6 (≥100 mg/day long-term) is associated with sensory neuropathy, ataxia, and skin lesions; monitor for numbness or tingling.
- P5P may be preferred in individuals with poor conversion of pyridoxine due to genetic or hepatic factors.
- B6 supplementation can interact with medications such as levodopa (reduces efficacy unless co-administered with carbidopa), isoniazid, and antiepileptics.
- Use caution in cancer patients; high-dose B6 may promote tumor progression in certain cancers based on emerging evidence [6].
- Combination with magnesium enhances bioavailability and may improve outcomes in stress and PMS.
Research
Higher dietary intake of vitamin B6 is associated with reduced stroke risk in a dose-response meta-analysis of prospective studies.
B vitamin supplementation, including B6, effectively reduces homocysteine levels in healthy adults, with combinations of B6, B9, and B12 showing strong efficacy.
Supplementation with 25 mg B6, 2 mg folic acid, and 0.5 mg B12 did not significantly improve antidepressant response over 52 weeks in older adults with depression.
High-dose B6 (50 mg/day) as part of a B-vitamin regimen showed no significant reduction in cardiovascular events among high-risk women.
Adjunctive B6 (25 mg/day), B12, and folic acid did not significantly improve depressive symptoms in a 12-month trial despite lowering homocysteine.
Evidence on B6 supplementation in cancer is mixed; high doses may interfere with certain chemotherapies or promote tumor progression in some contexts.
Higher serum B6 levels are associated with lower incidence of metabolic syndrome in a US cohort, suggesting a protective metabolic role.
Combination of 30 mg B6 and 300 mg magnesium significantly reduced perceived stress compared to magnesium alone in stressed adults with low magnesium.
