Vitamin B6

Your intake

What each level of vitamin b6 does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 mg – 0.56 mg

   Well below target. Risk of deficiency symptoms tied to amino acid metabolism.

2. Insufficient

   0.56 mg – 1.7 mg

   Below the recommended daily target. Long-term adequacy not assured.

3. Adequate

   1.7 mg – 2.55 mg

   Daily target met. Standard nutritional support for amino acid metabolism.

4. Therapeutic

   2.55 mg – 3.4 mg

   Common for specific health goals. Check the evidence for your situation before sustaining this level.

5. High

   3.4 mg – 100 mg

   Approaching the tolerable upper limit. Monitor and consider clinical guidance.

6. Over upper limit

   100 mg – +

   Above the tolerable upper limit. Risk of adverse effects — back off or consult a clinician.

Overview

B6 is the most metabolically versatile B vitamin — its active form pyridoxal-5-phosphate (PLP) is a cofactor for ~150 enzymes in amino acid, neurotransmitter, glucose, and heme metabolism. The B6 paradox: routine adequate intake is essential, but chronic high-dose supplementation causes sensory neuropathy.

Functions

• ●Cofactor for amino acid transaminations and decarboxylations
• ●Required for synthesis of serotonin, dopamine, GABA, glycine
• ●Cofactor in heme synthesis (ALA synthase)
• ●Cofactor in homocysteine remethylation and transsulfuration

Mechanism

PLP forms a Schiff base with substrate amino acids, stabilising carbanion intermediates that allow transamination, decarboxylation, and racemisation reactions. PLP-dependent enzymes drive the rate-limiting steps of neurotransmitter synthesis — which is why B6 affects mood and sleep regulation.

Benefits

• ●Reduces nausea in pregnancy (10–25 mg three times daily, often with doxylamine)
• ●Modestly reduces PMS symptoms (especially mood-related)
• ●Required for treatment of B6-responsive seizures in neonates
• ●Possible reduction in homocysteine when paired with B12 and folate

Deficiency

Isolated B6 deficiency is rare; more commonly seen alongside other B-vitamin shortfalls in chronic alcoholism, malabsorption, or with specific medications.

Excess

Chronic intake above ~100 mg/day causes dose- and duration-dependent sensory neuropathy that can take years to recover. Often reversible after discontinuation but not always.

Forms

• Pyridoxine HCl
  Standard inexpensive supplement; requires conversion to PLP
• Pyridoxal-5-phosphate (P5P/PLP)
  Active coenzyme; bypasses conversion (relevant in liver disease)
• Pyridoxamine
  Inhibits advanced glycation end-products; small clinical data

Food sources

• Chickpeas (cooked) · 1 cup1.1 mg
• Cooked tuna · 3 oz0.9 mg
• Cooked salmon · 3 oz0.6 mg
• Cooked chicken breast · 3 oz0.5 mg
• Banana · 1 medium0.4 mg
• Baked potato (with skin) · 1 medium0.4 mg

Supplement forms

Pyridoxal-5-phosphate (P5P/PLP) is the active form and bypasses the conversion step. Standard pyridoxine HCl works fine for most people. Avoid chronic doses above 100 mg/day unless clinically directed — sensory neuropathy from over-supplementation is real.

Bioavailability

All three forms are dephosphorylated in the gut, absorbed as pyridoxal/pyridoxine/pyridoxamine, then re-phosphorylated in tissues. About 75% of food B6 is bioavailable. Riboflavin (FAD) is required for PLP synthesis — low B2 status creates functional B6 deficiency.

Longevity relevance

Adequate but not excessive. The U-shape is real: deficiency drives neuro and cardio risk, excess drives neuropathy. Whole-food intake is the safer route; supplements above ~10 mg/day deserve a reason.

Relationships

References

• NIH ODS — Vitamin B6guideline
• Linus Pauling Institute — Vitamin B6review
• Schaumburg — sensory neuropathy from pyridoxine (NEJM 1983)study

About Vitamin B6

Pyridoxal-5-phosphate; neurotransmitter and amino acid metabolism.

Role

Amino acid metabolism

Daily target

1.7 mg (DV)

Upper limit

100 mg

Also called

vitamin b6, vitamin b-6, pyridoxine, pyridoxine hcl, pyridoxal, pyridoxal-5-phosphate