Vitamins & Minerals

Vitamin B6 (Pyridoxine)

Vitamin B6 (pyridoxal 5'-phosphate in its active form) is a water-soluble vitamin involved in over 150 enzymatic reactions. It is critical for amino acid metabolism, neurotransmitter synthesis (serotonin, dopamine, GABA), haemoglobin formation, and immune function. Unlike fat-soluble vitamins, B6 is not stored in significant quantities and must be replenished regularly through diet.

Optimal Ranges

Clinical (NHS) Range

20-125 nmol/L

nmol/L

Performance-Optimised Range

50-125 nmol/L

nmol/L

The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best.

Why It Matters

Why Vitamin B6 matters for performance

B6 is a cofactor in the production of key neurotransmitters — serotonin for mood, dopamine for motivation, and GABA for calm focus. Deficiency can directly impair mental performance and sleep quality. For active men, B6 supports the conversion of glycogen to glucose during exercise and is involved in steroid hormone modulation (it helps reduce excess oestrogen by supporting liver clearance). B6 also works with folate and B12 to regulate homocysteine — deficiency in any of the three raises cardiovascular risk.

Symptoms

Signs your levels may be off

Low / Deficiency

  • Irritability and low mood
  • Confusion and difficulty concentrating
  • Cracked lips and sore tongue (glossitis)
  • Weakened immune function
  • Peripheral neuropathy (tingling in hands/feet)

High / Excess

  • Nerve damage (peripheral neuropathy) with chronic high doses (>100mg/day)
  • Photosensitivity
  • Nausea and heartburn

Dietary Sources

Foods that support Vitamin B6 levels

Chicken and turkey breastSalmon and tunaChickpeas and other legumesPotatoes and starchy vegetablesBananas and avocados

Supplementation

Evidence-based supplementation

Most B6 supplements use pyridoxine hydrochloride, but pyridoxal 5'-phosphate (P5P) is the active coenzyme form and may be better absorbed by those with liver impairment or genetic variants affecting conversion. Standard supplemental dose is 10-50mg daily. The UK tolerable upper limit is 200mg/day (long-term), but chronic doses above 100mg can cause reversible nerve damage. B6 is best taken as part of a B-complex rather than in isolation, as B vitamins work synergistically. Taking B6 in the morning may support daytime neurotransmitter production without disrupting sleep.

Research

Key study

Vitamin B6 and its role in cell metabolism and physiology

Parra M, Stahl S, Hellmann H

Cells (2018)

DOI: 10.3390/cells7070084

Related Biomarkers

Vitamins & Minerals

Vitamin B12 (Cobalamin)

Optimal: 500-800 pg/mL

Vitamins & Minerals

Folate (Vitamin B9)

Optimal: 20-45 nmol/L

Vitamins & Minerals

Magnesium (Serum)

Optimal: 0.85-1.0 mmol/L

Related Guides

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Complete Guide to Blood Tests

What to test and why it matters

Test your Vitamin B6 levels

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This content is for educational purposes only and does not constitute medical advice. Your data suggests areas for optimisation, but any concerns should be discussed with a qualified healthcare professional. If your results flag values outside safe ranges, we recommend consulting your GP.