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PY

Vitamin B6 (Pyridoxine)

water-soluble

Vitamin
(15 studies)

Key Takeaways

  • FDA daily value is 1.7 mg
  • Cofactor for 100+ enzymatic reactions
  • Excess B6 causes neuropathy (pmid:41609902, pmid:40418248)
  • Used as antiemetic in pregnancy and with isoniazid
  • Active form is pyridoxal 5-phosphate (PLP)

Evidence Spectrum

15 studies reviewed →
Strong (2)
Moderate (1)

Isoniazid neuropathy prevention

INH competitively inhibits B6; supplementation prevents peripheral neuropathy.4

Antiemetic in pregnancy

Used for pregnancy nausea including in doxylamine-pyridoxine combinations.13

Pyridoxine-responsive seizures

IV pyridoxine causes dramatic seizure cessation in deficiency states.25

15

Studies Reviewed

1.7 mg

RDA (Adults (FDA Daily Value))

100 mg

Upper Limit

water-soluble

Solubility

Role in the Body

Vitamin B6 (pyridoxine) is closely associated with nervous, immune, and endocrine systems. PLP serves as cofactor for 100+ reactions, primarily amino acid metabolism (pmid:24035968). B6 contributes to neurotransmitter synthesis and inhibits glutamate release (pmid:34477538). Excess B6 rather than deficiency causes neuropathy in developed countries (pmid:41609902, pmid:40418248).

  • Cofactor for 100+ amino acid metabolism reactions
  • Neurotransmitter synthesis (serotonin, dopamine, GABA)
  • Hemoglobin synthesis
  • Immune function
  • Glutamate modulation

Supplement Forms

Pyridoxine HCl

Recommended

Bioavailability: 0.75%

Most common supplement form

Pyridoxal 5-phosphate (P5P)

Recommended

Bioavailability: 0.5%

Active coenzyme form

Food Sources

Poultry

Fish

Potatoes

Chickpeas

Bananas

Fortified cereals

Beef liver

Deficiency

Prevalence: Isolated B6 deficiency uncommon; excess intake neuropathy more common in developed countries (pmid:41609902).

Symptoms:

  • Seborrheic dermatitis
  • Microcytic anemia
  • Convulsions in infants
  • Depression
  • Neuropathy (from excess)

Risk Factors:

  • Chronic alcoholism
  • Isoniazid therapy (pmid:6269259)
  • Elderly populations

Safety & Interactions

Possible Side Effects:

  • • Sensory neuropathy above 200 mg/day (pmid:15666709, pmid:40418248)
  • • CNS effects resolving on cessation (pmid:40418248)

Drug Interactions:

  • • Isoniazid inhibits B6 (pmid:6269259)
  • • May reduce levodopa effectiveness

Contraindications:

  • • Levodopa monotherapy patients avoid high-dose B6

Frequently Asked Questions

Can you take too much B6?

Yes. Chronic intake above 200 mg/day can cause sensory neuropathy. UL is 100 mg/day.

Research Sources

15 peer-reviewed studies analyzed from PubMed. 5 directly cited in this review.

View All Sources
1The Pharmacological and Clinical Roles of Antiemetics: A Narrative Review.
2Vitamin B6: deficiency diseases and methods of analysis.
3[Vitamin B6 (Pyridoxine)--excessive dosage in food supplements and OTC medications].