Vitamin B6 — known chemically as pyridoxine in its most common supplemental form — is a water-soluble B vitamin with an exceptionally broad range of biochemical roles. It serves as a coenzyme in over 100 enzymatic reactions, most of which involve amino acid metabolism. This makes B6 relevant to protein utilisation, neurotransmitter synthesis, haemoglobin production, immune function, hormone regulation, and homocysteine management. Despite being widely available in food and rarely deficient in populations eating a varied diet, B6 insufficiency does occur in specific groups — and high-dose supplementation carries well-documented neurological risks that are frequently underappreciated.
The Active Form of Vitamin B6: Pyridoxal-5-Phosphate
Vitamin B6 is not a single compound but a family of six interconvertible vitamers: pyridoxine, pyridoxal, pyridoxamine, and their respective 5-phosphate forms. All three non-phosphorylated forms are absorbed from the gastrointestinal tract and converted in the liver to pyridoxal-5-phosphate (P-5-P) — the biologically active coenzyme form that participates in enzymatic reactions throughout the body.
Pyridoxine hydrochloride (pyridoxine HCl) is the form used in most conventional supplements and is effective for the majority of people. However, individuals with impaired liver function, certain genetic variants affecting B6 metabolism, or specific health conditions may benefit from supplementing directly with P-5-P, which bypasses the hepatic conversion step. P-5-P supplements are slightly more expensive but may be preferable for those with absorption or conversion concerns. Both pyridoxine HCl and P-5-P supplements are available in our vitamin B collection.
What Vitamin B6 Does in the Body
As a coenzyme in amino acid metabolism, P-5-P participates in transamination, deamination, and decarboxylation reactions — the reactions that interconvert amino acids, convert them to energy, or transform them into other biologically active molecules. This enzymatic role makes B6 relevant to:
- Neurotransmitter synthesis — B6 is essential for producing serotonin (from tryptophan), dopamine, noradrenaline, GABA, and histamine. This connection to neurotransmitter levels makes B6 status directly relevant to mood regulation, sleep quality, and cognitive function.
- Haemoglobin production — B6 is required for the synthesis of haem, the iron-containing component of haemoglobin; deficiency can contribute to a microcytic anaemia that resembles iron deficiency anaemia in blood tests
- Immune function — B6 supports lymphocyte proliferation and antibody production; B6 deficiency impairs immune responses, and adequacy is particularly important during illness and periods of high physiological stress
- Homocysteine regulation — alongside folate and B12, B6 participates in the transsulphuration pathway that converts homocysteine to cysteine; all three B vitamins are needed for complete homocysteine management, which has implications for cardiovascular and neurological health
- Glycogen metabolism — B6 is involved in glycogenolysis (the release of glucose from glycogen stores), making it relevant to energy availability during fasting and exercise
- Hormone balance — B6 influences the activity of steroid hormone receptors and is involved in oestrogen and progesterone metabolism, which contributes to its use in women's health contexts
Dietary Sources of Vitamin B6
Vitamin B6 is widely distributed in both animal and plant foods. The richest sources include:
- Poultry and pork — chicken, turkey, and pork are among the most concentrated animal sources
- Fish — tuna, salmon, and cod provide substantial amounts
- Whole grains and pseudograins — buckwheat (one of the richest grain sources), brown rice, oats, and whole wheat
- Starchy vegetables — potatoes (with skin) and sweet potatoes are good plant sources
- Legumes — chickpeas and lentils contribute meaningfully
- Nuts — pistachios are particularly high in B6; sunflower seeds also provide relevant amounts
- Bananas — one of the better fruit sources
B6 is sensitive to heat and light, with cooking reducing content by up to 50% in some foods. The bioavailability of B6 from animal sources is generally higher (approximately 70–80%) than from plant sources (approximately 45–65%), where it occurs partly in glycosylated forms that are less efficiently absorbed. This may be relevant for those following strict plant-based diets.
Who Is at Risk of Vitamin B6 Deficiency?
Outright B6 deficiency is uncommon in healthy people eating a varied diet, but subclinical insufficiency is more prevalent than is often recognised. Groups at elevated risk include:
- Women taking oral contraceptives — oestrogen-containing contraceptives increase B6 requirements by affecting its metabolism; women on the pill for extended periods are among the most commonly cited at-risk groups
- Pregnant women — foetal demand increases maternal B6 requirements; adequate B6 also contributes to the management of pregnancy-related nausea, with B6 supplementation used clinically for morning sickness at doses of 10–25 mg three times daily under medical guidance
- Older adults — absorption decreases and requirements may increase with age; B6 is included in most senior multivitamin formulations for this reason
- Individuals with alcohol dependency — alcohol impairs B6 absorption and accelerates its breakdown
- Those taking certain medications — isoniazid (anti-tuberculosis medication), certain anticonvulsants, and cycloserine can deplete B6 or interfere with its metabolism
Symptoms of deficiency include microcytic anaemia, dermatitis and seborrheic skin changes, mouth sores and glossitis, depression, irritability, impaired immune function, and in severe cases, peripheral neuropathy and seizures. Explore our immune system supplements collection for B6-containing products alongside broader immune support options.
[tip:Vitamin B6 works synergistically with magnesium in many enzymatic pathways — this is why magnesium + B6 combinations are among the most popular supplement pairings for stress, muscle function, and sleep support. B6 also functions most effectively when folate and B12 are also adequate, as the three vitamins operate together in homocysteine metabolism.]Daily Requirements
The EU Nutrient Reference Value for vitamin B6 is 1.4 mg/day for adults. Requirements increase modestly during pregnancy (1.9 mg/day) and breastfeeding (2.0 mg/day). The EU tolerable upper intake level (UL) for supplemental B6 from all sources is 12.5 mg/day — a figure that reflects documented safety concerns around peripheral neuropathy at higher doses.
Vitamin B6 and the Upper Intake Limit: An Important Safety Note
Vitamin B6 is unusual among the B vitamins in having a well-established upper safety limit and a documented toxicity syndrome. Peripheral neuropathy — characterised by numbness, tingling, burning pain, and impaired coordination in the hands and feet — has been documented in individuals taking supplemental B6 at doses that may appear moderate: cases have been reported at chronic intakes as low as 50–100 mg/day, and are well-documented at 200 mg/day and above.
This is not a remote risk: peripheral neuropathy attributed to B6 excess is the most common adverse effect of B-vitamin supplementation reported in European pharmacovigilance databases. Importantly, the neuropathy is usually reversible when supplementation is discontinued, but recovery can take months and may be incomplete in severe cases. The EU's UL of 12.5 mg/day is deliberately conservative to reflect this risk profile. For most people seeking general B6 supplementation, doses in the 1.4–10 mg range are appropriate. Standard B-complex supplements (B-50 or B-100 products providing 50–100 mg) supply doses that exceed this UL — and should not be used as long-term daily supplements without medical oversight.
[warning:Do not supplement with high-dose vitamin B6 (above 25 mg/day) for extended periods without medical supervision. Chronic intake above 50–100 mg/day has been associated with peripheral sensory neuropathy — numbness, tingling, and pain in the extremities. The EU tolerable upper intake level is 12.5 mg/day from supplemental sources. If you develop numbness or tingling in your hands or feet while taking B6 supplements, discontinue use and consult a healthcare professional. Doses used in some clinical applications (e.g. pregnancy nausea, PMS) are above this UL and should be medically supervised and time-limited.]Standalone vitamin B6 / P-5-P supplements:
[products: aliness-vitamin-b6-p-5-p-25-mg-100-tablets, formeds-bicaps-p-5-p-60-capsules, haya-labs-vitamin-b6-p-5-p-40-mg-90-tablets, medverita-p-5-p-coenzymatic-vitamin-b6-25-mg-120-capsules, now-foods-vitamin-b-6-100-mg-100-veg-capsules, solgar-vitamin-b6-50-mg-100-tablets]Magnesium and vitamin B6 combinations — the classic synergistic pairing:
[products: solgar-magnesium-with-vitamin-b6-100-tablets, aliness-chelated-magnesium-vitamin-b6-100-capsules, vitalers-magnesium-125-mg-vitamin-b6-120-capsules, formeds-bicaps-p-5-p-60-capsules, formeds-prenacaps-mag-b6-60-capsules] [note:All Medpak products are shipped from within the European Union, ensuring fast and reliable delivery across Europe with no customs fees or import complications.]
