Vitamin B6
Vitamin B6 is a water-soluble B-vitamin the body uses for amino-acid metabolism, neurotransmitter and haemoglobin synthesis, and immune function. UK NHS reference intakes are 1.4 mg/day for men and 1.2 mg/day for women. Most people get enough from food. NHS guidance cautions against long-term supplemental intakes above 10 mg/day because chronic high doses can cause peripheral nerve damage.
Camden Medicals editorial · Last reviewed 27 April 2026 · Next review October 2026
- Cross-checked against
- NHS
- NICE
- BNF
- EFSA
- FSA
Camden's editorial team independently graded each health claim below on the strength of the published evidence — see the grade beside every condition.
- Class
- Vitamin
- NHS daily RNI
- 1.4 mg ♂ · 1.2 mg ♀
- Typical supplemental
- 10-50 mg/day appears in PMS literature; 30-100 mg/day across four daily doses for nausea and vomiting in pregnancy under clinical advice.
- Top use evidence
- Strong
On this page
What it is
Vitamin B6 is the umbrella name for six closely-related cobalt-free pyridine compounds called vitamers: pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM), and their 5'-phosphorylated forms PNP, PLP, and PMP. The body interconverts them and phosphorylates them to pyridoxal-5'-phosphate (PLP), the active coenzyme used by around 140 enzymes in human metabolism.
UK food sources include poultry, fish (especially salmon and tuna), potatoes (with skin), bananas, chickpeas, fortified breakfast cereals, and milk. Cooking and food processing can degrade B6 modestly — fresh, minimally-processed sources retain the most.
Two supplemental forms dominate the UK market. Pyridoxine hydrochloride is the most common — it is cheap, very stable, and is converted to PLP in the liver. Pyridoxal-5-phosphate (P5P) is sold as the "pre-active" form at a higher price; the marketing argument is that it bypasses a conversion step. Head-to-head bioavailability and clinical-outcome data in healthy adults are limited, and for most people the practical difference is small. The NHS injectable B6 used in vitamin-deficiency clinical pathways is pyridoxine hydrochloride.
At a glance
- NHS adult RNI: 1.4 mg/day (men), 1.2 mg/day (women).
- NHS guidance: do not take more than 10 mg/day from supplements long-term unless directed by a doctor; ≥200 mg/day can cause peripheral neuropathy.
- Supplemental forms: pyridoxine hydrochloride (most common, low cost) and pyridoxal-5-phosphate (P5P, the active coenzyme). Both work; head-to-head clinical evidence in healthy adults is limited.
- NICE-recognised uses: pyridoxine 10–25 mg three or four times a day for nausea and vomiting in pregnancy; some clinicians use 50–100 mg/day for premenstrual symptoms — evidence is older and methodologically limited.
What people use it for
Adults eating a varied UK diet
Most adults meet the 1.4 mg (men) / 1.2 mg (women) NHS RNI from food alone. Routine supplementation is rarely needed if diet includes poultry, fish, potatoes, bananas, or fortified cereals. [1]
Some evidenceStrongWomen with premenstrual symptoms
Older trials (synthesised in Wyatt et al 1999, BMJ) reported modest reductions in PMS scores at doses up to 100 mg/day, but methodological quality was limited. NICE CKS lists vitamin B6 as one of several options women may try; evidence is not strong, and chronic high doses risk peripheral neuropathy. Discuss with your pharmacist or GP before starting. [8,2]
Some evidenceLimitedPregnant women with nausea and vomiting
Pyridoxine is one of the longest-standing first-line options for nausea and vomiting in pregnancy. Typical regimens described in the literature are 10–25 mg three or four times a day, often combined with doxylamine in licensed prescription products in some markets. Speak to a midwife, GP, or pharmacist before starting in pregnancy. [9,10]
Some evidenceModeratePeople taking isoniazid, penicillamine, or hydralazine
These medicines deplete B6 or interfere with its function. Pyridoxine is routinely co-prescribed alongside isoniazid in UK TB pathways to prevent isoniazid-induced peripheral neuropathy. Dosing is a clinical decision — talk to your prescriber. [1]
Some evidenceStrongOlder adults
Mild B6 inadequacy is more common with age, partly through reduced intake and partly through medicine interactions (e.g. theophylline, some antiepileptics). UK food-based intake is the first port of call; supplemental intake should remain within NHS guidance unless directed by a clinician. [1]
Some evidenceModerate
How it works
As pyridoxal-5-phosphate (PLP), vitamin B6 is the coenzyme for around 140 enzymes — including those that build and break down amino acids, synthesise neurotransmitters (serotonin, dopamine, GABA), make haemoglobin via the haem pathway, and recycle homocysteine to cysteine in the transsulfuration pathway.
Common myths
Myth"Vitamin B6 fixes carpal tunnel syndrome"
RealityHigh-dose B6 for carpal tunnel was a popular claim in the 1970s and 1980s but is not supported by current systematic reviews. Carpal tunnel syndrome has well-established management pathways (wrist splints, corticosteroid injection, decompression surgery in selected cases) — talk to your GP if you have symptoms.
Myth"P5P (pyridoxal-5-phosphate) is dramatically better than pyridoxine HCl"
RealityBoth work. The body converts pyridoxine HCl to the active coenzyme PLP in the liver. P5P supplements skip that conversion step — a plausible but not strongly evidenced advantage in healthy adults with normal liver function. Head-to-head clinical-outcome data are limited; the price gap is often larger than the bioavailability gap.
Myth"High-dose B6 is always safe because it is water-soluble"
RealityWater-soluble does not mean unlimited. Chronic intakes above 100 mg/day (consistently above 200 mg/day) have caused peripheral sensory neuropathy in case series and large cohorts (Schaumburg et al 1983, NEJM). The European Scientific Committee on Food set an adult Tolerable Upper Intake Level of 25 mg/day; UK NHS guidance is to stay below 10 mg/day from supplements long-term without clinical advice. The US figure of 100 mg/day is the US Institute of Medicine UL, not the EU/UK value. [11]
Myth"B6 cures depression"
RealitySevere B6 inadequacy is associated with low mood, and replacement corrects the picture. The leap from "associated with deficiency" to a depression remedy in non-deficient adults is not supported by current evidence. The GB-authorised health claim is that B6 contributes to normal psychological function — a claim about adequacy supporting normal function, not a remedy claim. If your mood is affecting your day-to-day, talk to your GP about evidence-based options. [6]
Myth"B6 megadoses give you more energy"
RealityThe GB-authorised claim is that B6 contributes to "the reduction of tiredness and fatigue" — a function-of-adequacy claim. There is no good evidence that supplementing above adequacy produces above-normal energy in healthy adults, and the dose-related neuropathy risk above 100–200 mg/day is well documented. Megadosing is not a route to more energy. [6]
Common online questions
Synthesised from the questions UK shoppers most often ask online about Vitamin B6. Each answer is editorial and links to its evidence in the Sources list below.
Pyridoxine HCl vs P5P — is the active form worth the extra money?
For most healthy adults, the practical difference is small. Pyridoxine hydrochloride is converted to the active form (pyridoxal-5-phosphate, PLP) in the liver; this conversion is not usually rate-limiting. P5P supplements are marketed as "pre-active" and skip that conversion step, which is a plausible but not strongly evidenced advantage in healthy adults. The price difference is real; the clinical-outcome difference is not well established. Read the elemental B6 amount on both — that is the figure that matters most.
How much B6 do you take for PMS?
Doses of 50–100 mg/day appear in older PMS trials (Wyatt et al 1999 systematic review). NICE Clinical Knowledge Summaries lists vitamin B6 among options women may try while flagging that evidence quality is limited. NHS guidance is clear that long-term intakes above 10 mg/day from supplements carry a peripheral-neuropathy risk and should not be taken without clinical advice. For PMS specifically, talk to your pharmacist or GP — there are evidence-based options worth discussing alongside (or instead of) high-dose B6. [8,2]
How much B6 for morning sickness?
Trials of pyridoxine for nausea and vomiting in pregnancy typically used 10–25 mg three or four times a day. UK clinical pathways (and the licensed combination doxylamine-pyridoxine in some markets) sit in this same range. Pregnancy is not a context for self-medicating with a high-dose supplement — speak to a midwife, GP, or pharmacist before starting any supplement in pregnancy. [9]
Can you overdose on B6?
Yes — this is the single most important safety message about B6. Although it is water-soluble, chronic intakes above 100 mg/day (and consistently above 200 mg/day) have caused peripheral sensory neuropathy — numbness, tingling, and ataxia — first described in seven adults by Schaumburg et al in the 1983 NEJM "megavitamin syndrome" paper. NHS guidance is to keep supplemental B6 below 10 mg/day for long-term use unless a clinician has advised otherwise. [11,1]
Is the B6 + magnesium combination good for PMS?
It is a popular combination. Direct trial evidence for the combination specifically is thin; most evidence is from single-ingredient trials. Magnesium has the GB-authorised claim that it contributes to normal psychological function; B6 has the same. Whether co-supplementing produces a meaningful additional effect on PMS symptoms is not well established. NHS guidance keeps both well below their respective neuropathy and bowel-tolerance ceilings.
Does vitamin B6 interact with levodopa?
High-dose B6 (around 5 mg or more) was historically a problem for plain levodopa: B6 accelerates levodopa breakdown in the periphery and reduces the dose reaching the brain. Modern Parkinson's prescriptions almost always combine levodopa with carbidopa (or benserazide), which blocks this peripheral conversion and largely neutralises the B6 interaction. If you take a levodopa-containing medicine, talk to your pharmacist or GP before starting any B6 supplement.
Can high-dose B6 give you neuropathy?
Yes, and the threshold is lower than people often assume. The classic case series is Schaumburg et al 1983, NEJM — seven adults developed sensory neuropathy on chronic high-dose pyridoxine. The European Scientific Committee on Food set a Tolerable Upper Intake Level of 25 mg/day for adults, and EFSA's 2023 re-evaluation lowered the adult UL to 12 mg/day (EFSA Journal 2023, DOI 10.2903/j.efsa.2023.8006); the NHS is more conservative still and advises against chronic supplemental intakes above 10 mg/day without clinical advice. Symptoms usually resolve when the supplement is stopped, but recovery can be slow and is not always complete. [11,1]
⚖️ The official position
What may lawfully be claimed about Vitamin B6 in Great Britain. This is a regulatory position, not an evidence grade.
A health claim is authorised in Great Britain.
“Vitamin B6 contributes to normal cysteine synthesis”
“Vitamin B6 contributes to normal energy-yielding metabolism”
“Vitamin B6 contributes to normal functioning of the nervous system”
“Vitamin B6 contributes to normal homocysteine metabolism”
“Vitamin B6 contributes to normal protein and glycogen metabolism”
“Vitamin B6 contributes to normal psychological function”
“Vitamin B6 contributes to normal red blood cell formation”
“Vitamin B6 contributes to the normal function of the immune system”
“Vitamin B6 contributes to the reduction of tiredness and fatigue”
“Vitamin B6 contributes to the regulation of hormonal activity”
This claim is authorised for use in Great Britain under the GB Nutrition and Health Claims regulation. A product may carry it when it provides at least 15% of the UK NRV per recommended daily portion.
Authorised UK health claims
Verbatim from the GB Nutrition and Health Claims Register (Reg 432/2012 as assimilated in GB). A product can carry these claims when it provides at least 15% of the UK NRV per recommended daily portion.
10 authorised claims — show / hide
- "Vitamin B6 contributes to normal cysteine synthesis"
- "Vitamin B6 contributes to normal energy-yielding metabolism"
- "Vitamin B6 contributes to normal functioning of the nervous system"
- "Vitamin B6 contributes to normal homocysteine metabolism"
- "Vitamin B6 contributes to normal protein and glycogen metabolism"
- "Vitamin B6 contributes to normal psychological function"
- "Vitamin B6 contributes to normal red blood cell formation"
- "Vitamin B6 contributes to the normal function of the immune system"
- "Vitamin B6 contributes to the reduction of tiredness and fatigue"
- "Vitamin B6 contributes to the regulation of hormonal activity"
Camden guides citing Vitamin B6
Editorial pieces from the Camden blog that reference Vitamin B6. Each guide cites the evidence it draws on.
🔬 Camden’s evidence review
The research Camden reviewed, graded on its strength. This is our own appraisal — it sits beneath the official guidance above, never above it.
Premenstrual symptoms
LimitedEvidencelimitedWyatt et al's 1999 BMJ systematic review of nine placebo- controlled trials (940 women) reported an overall odds ratio of 1.57 in favour of B6 for overall PMS symptoms, rising to 2.32 when one heterogeneous trial was removed; the authors noted that conclusions were limited by the low quality of most included trials. The earlier Cochrane protocol on this topic (CD002919) was withdrawn. NICE Clinical Knowledge Summaries currently lists vitamin B6 among options women may try, while flagging that evidence quality is limited and that chronic high-dose use risks peripheral neuropathy. [8,2]
Nausea and vomiting in pregnancy
ModerateEvidencemoderatePyridoxine 10–25 mg three or four times a day reduced nausea scores compared with placebo in randomised trials synthesised by a 2023 systematic review and meta-analysis (Jayawardena et al., Archives of Gynecology and Obstetrics). Combination doxylamine-pyridoxine is a licensed prescription medicine for nausea and vomiting in pregnancy in some markets and appears in UK clinical pathways when first-line measures (rest, hydration, ginger) are not enough — discuss with a midwife, GP, or pharmacist. [9,10]
Cardiovascular events through homocysteine lowering
InsufficientEvidenceinsufficientB6 with B12 and folate lowers blood homocysteine, but four large randomised trials (HOPE-2, VISP, NORVIT, SEARCH) and the 2017 Cochrane review (Martí-Carvajal CD006612, 86,393 participants) did not find that this lowering reduced myocardial infarction or all-cause mortality in adults at cardiovascular risk. A small reduction in stroke was reported in pooled analyses; major clinical-event benefit is not established. [7,12,13,14,15]
B6-deficiency dermatitis and peripheral neuropathy
StrongEvidencestrongFrank vitamin B6 inadequacy is uncommon in the UK general population but well-described — clinical features include seborrhoeic dermatitis, glossitis, peripheral neuropathy, and (in severe cases) a microcytic anaemia. Replacement corrects the picture. Diagnosis and treatment of clinical B6 inadequacy are a clinical decision; do not self-medicate suspected inadequacy with high-dose B6 — see your GP or pharmacist. [1]
Safety
Vitamin B6 at the levels in a normal diet (1.4 mg/day for men, 1.2 mg/day for women) is safe and necessary. Supplemental B6 above 10 mg/day long-term is the level where the NHS advises clinical input — chronic intakes above 100–200 mg/day can cause peripheral nerve damage.
Talk to your pharmacist or GP first if you:
- You take levodopa (especially without carbidopa or benserazide) — high-dose B6 can reduce its effect.
- You take isoniazid for tuberculosis — pyridoxine is often co-prescribed at a clinician-set dose to prevent isoniazid-induced neuropathy.
- You take penicillamine or hydralazine — these can deplete B6 or interfere with its function.
- You take phenytoin or phenobarbital — high-dose B6 can lower blood levels of these antiepileptics.
- You are pregnant — for nausea and vomiting in pregnancy, NICE and clinical practice describe pyridoxine 10–25 mg three or four times a day, but pregnancy is not a context to self-medicate. Speak to your midwife, GP, or pharmacist first.
- You are considering doses above 10 mg/day long-term for any reason — peripheral neuropathy is a documented risk at chronic high doses.
Common side effects: Generally very well tolerated at typical supplemental doses. The main safety concern is peripheral sensory neuropathy from chronic intakes above 100–200 mg/day.
Pregnancy and breastfeeding
The NHS RNI for B6 is unchanged in pregnancy (1.2 mg/day). For nausea and vomiting in pregnancy, pyridoxine in clinically described regimens (typically 10–25 mg three or four times a day) is one of the longer-standing first-line options and is reflected in UK clinical pathways. Pregnancy is not a context for self-medicating with a supplement — speak to a midwife, GP, or pharmacist before starting.
NHS RNI is 1.2 mg/day in breastfeeding. Higher supplemental doses should be discussed with a pharmacist or GP.
Talk to your GP, midwife, or pharmacist before starting any supplement during pregnancy or breastfeeding.
More clinical detail (for clinicians and informed readers)
Contraindications
- Known hypersensitivity to pyridoxine, pyridoxal-5-phosphate, or any product excipient.
Drug interactions
- Levodopa (non-combined preparations) — high-dose B6 accelerates peripheral levodopa breakdown and reduces its effect; modern carbidopa-levodopa or benserazide-levodopa combinations are largely unaffected (BNF pyridoxine entry).
- Isoniazid — depletes B6 and can cause peripheral neuropathy; pyridoxine is routinely co-prescribed at a clinician-set dose.
- Penicillamine — depletes B6.
- Hydralazine — can deplete B6 and cause neuropathy at high doses.
- Phenytoin and phenobarbital — high-dose B6 has been reported to lower blood concentrations of these antiepileptics.
- Amiodarone — theoretical photosensitivity at high B6 doses; clinical relevance uncertain.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- Generally well tolerated at typical supplemental doses (≤10 mg/day).
Rare side effects
- Peripheral sensory neuropathy — numbness, tingling, and ataxia in hands and feet — described at chronic intakes ≥100–200 mg/day, especially over months to years (Schaumburg et al 1983, NEJM).
- Photosensitivity has been reported at very high doses.
- Mild nausea on an empty stomach at higher doses.
How to take it
- UK Reference Nutrient Intake
- 1.4 mg/day (men) · 1.2 mg/day (women)
- Typical supplemental range
- 10-50 mg/day appears in PMS literature; 30-100 mg/day across four daily doses for nausea and vomiting in pregnancy under clinical advice.
- Timing
- Anytime — water-soluble.
How to spot quality
Look for
- Form named explicitly: pyridoxine hydrochloride or pyridoxal-5-phosphate (P5P).
- Milligrams of B6 per serving stated alongside % NRV (UK NRV = 1.4 mg).
- Avoid products that say only "B-complex" without per-vitamin breakdown.
- GMP-certified manufacture; ideally third-party potency testing.
Red flags
- Doses above 25 mg/day in general (non-clinical) supplementation — above the EU SCF Tolerable Upper Intake Level for adults.
- Form simply listed as "vitamin B6" with no compound named.
- High-strength B6 (>50 mg) marketed for PMS, mood, or "energy" without context about the long-term peripheral-neuropathy risk.
- Combination products that hide the individual B6 dose inside a proprietary "B-complex" blend.
Where Camden lands · meets the bar
Camden's NB-500 (Magnesium Complex) carries 1.4 mg vitamin B6 as pyridoxine hydrochloride per three-capsule serving — that is 100% UK NRV and well below any toxicity threshold. The form is named on the label; manufacture is GMP-certified through Troo Health Care. Camden does not currently stock a standalone vitamin B6 SKU. People who need higher dedicated B6 doses (e.g. for nausea and vomiting in pregnancy or PMS, on clinician advice) should look for a single-ingredient product with the form and milligrams clearly named, and discuss with a pharmacist or GP before exceeding 10 mg/day long-term.
Commonly combined with
Other ingredients that share a biological pathway, cofactor relationship, or evidence-backed protocol with this one. Mechanisms below cite primary physiology — not folk pairing. Doses are literature ranges, not recommendations. Talk to your pharmacist or GP before changing your stack, especially if you take prescription medication.
Magnesium
Moderate evidenceB6 helps move magnesium into cells — the most-studied micronutrient pairing for PMS.
Vitamin B6 (pyridoxal-5-phosphate) facilitates the cellular uptake and intracellular retention of magnesium ions, particularly in erythrocytes and neuronal tissue. The combination is the single most-studied micronutrient pairing for premenstrual syndrome symptoms, with smaller bodies of evidence for migraine prophylaxis. Mechanistic plausibility is strong; trial quality is heterogeneous.
Evidence: Walker 1998 (J Womens Health Gend Based Med) RCT on Mg+B6 vs Mg alone for PMS. De Souza 2000 extended this. Cochrane reviews of either nutrient alone for PMS show modest, mixed effect; combination data is more positive but from smaller studies. [16,17]
Doses studied: 50 mg vitamin B6 with 200–400 mg magnesium daily (B6 dose well below the 100 mg/day chronic-neuropathy threshold)
Vitamin B12
Moderate evidenceB6 and B12 work together with folate in the methionine cycle that lowers homocysteine.
Vitamin B12 (methylcobalamin) is the cofactor for methionine synthase, which converts homocysteine back to methionine using a methyl group donated by 5-methyltetrahydrofolate. Vitamin B6 (pyridoxal-5-phosphate) is the cofactor for the parallel transsulfuration pathway, where cystathionine beta-synthase converts homocysteine to cystathionine, the precursor of cysteine and glutathione. Adequate status in both vitamins keeps plasma homocysteine within reference range; deficiency in either raises it. The HOPE-2, NORVIT and VISP trials confirmed that combined supplementation lowers measured homocysteine by 2-3 micromol/L on average, but did not reduce major cardiovascular event rates over 2-5 years follow-up.
Evidence: Lonn 2006 (HOPE-2, NEJM 354:1567) randomised 5,522 adults with vascular disease to 2.5 mg folic acid + 50 mg B6 + 1 mg B12 vs placebo for 5 years; homocysteine fell 2.4 micromol/L on treatment but the composite cardiovascular endpoint was unchanged (RR 0.95, p=0.41), with a 25% reduction in stroke offset by a 24% increase in unstable-angina hospitalisation. Bonaa 2006 (NORVIT, NEJM 354:1578) and Toole 2004 (VISP, JAMA 291:565) found similar null cardiovascular results despite confirmed homocysteine reduction. The combined-vitamin effect on homocysteine itself is well-established; the clinical-outcome benefit is not. [14,12,13]
Doses studied: 1.4 mg B6 + 2.5 ug B12 covers UK adult RNI; the homocysteine trials used 25-50 mg B6 + 0.4-1 mg B12 alongside folate.
Methyl Folate (5-Methyltetrahydrofolate)
Moderate evidenceB6 and folate together drive homocysteine clearance through the methionine cycle and transsulfuration pathway.
Methyl-folate (5-methyltetrahydrofolate) donates a methyl group to homocysteine (via methionine synthase, B12-dependent) to regenerate methionine. Vitamin B6 in its active form pyridoxal-5-phosphate is the cofactor for the alternative transsulfuration route (cystathionine beta-synthase) that diverts homocysteine to cysteine and glutathione. Folate alone reduces homocysteine substantially when folate status is the limiting factor; addition of B6 widens the clearance pipeline and targets residual elevation in adequately-folated individuals.
Evidence: The HOPE-2, NORVIT and VISP trials (Lonn 2006; Bonaa 2006; Toole 2004) all combined folic acid with B6 and B12; folic-acid-only arms in NORVIT and VISP showed homocysteine drops similar to the combined-vitamin arm, with no incremental cardiovascular benefit from adding B6. The case for combining B6 with folate rests on completeness of the cycle rather than on outcome trials demonstrating B6-attributable benefit beyond folate alone. [14,12,13]
Doses studied: 200-400 ug methyl-folate + 1.4 mg B6 covers UK adult intake; trial doses ran higher (0.4-2.5 mg folic acid + 25-50 mg B6).
Inositol (Myo-Inositol, D-Chiro-Inositol)
Limited evidenceHormonal-balance cluster — UK Article 13.1 authorised claim for B6 in hormonal regulation.
Vitamin B6 (pyridoxal-5-phosphate) is a cofactor for over 100 enzymatic reactions including the synthesis of dopamine, serotonin, and other monoamine neurotransmitters, and for amino-acid metabolism. UK Article 13.1 authorised claim "Vitamin B6 contributes to the regulation of hormonal activity" supports a hormonal-balance framing.
Inositol acts on insulin signalling and ovulation; B6 supports broader hormonal-activity context. The two are mechanism-supportive rather than synergistic, and feature together in many women''s-health and PCOS-targeted multivitamins.
Note: high-dose B6 (>10 mg/day chronically) has its own peripheral neuropathy concern. Camden's vitamin-b6 entry covers the dose ceiling.
Evidence: UK Article 13.1 B6 hormonal-regulation claim authorised (gb-nhc:vitamin_b6). Combination trial evidence limited. [6]
Doses studied: Myo-inositol 2-4 g/day + vitamin B6 1.4-10 mg/day. Higher B6 doses (>10 mg/day) are not advised because of peripheral neuropathy risk.
L-Tryptophan
Limited evidenceCofactor cluster — B6 (pyridoxal-5-phosphate) is the cofactor for aromatic L-amino acid decarboxylase that converts 5-HTP to serotonin.
B6 is the cofactor that l-tryptophan → 5-HTP → serotonin pathway requires at the AADC step. Adequate B6 supports flux through the pathway. UK Article 13.1 B6 psychological-function and nervous-system claims.
Evidence: UK Article 13.1 B6 claims authorised. [6]
Doses studied: 500-1000 mg l-tryptophan + 1.4-10 mg B6 evening.
St John's Wort (Hypericum perforatum)
Limited evidenceB6 (pyridoxal-5-phosphate) is a cofactor for serotonin and dopamine synthesis. Sometimes co-formulated with St John's Wort in mood supplements; mechanism is supportive rather than synergistic.
Pyridoxal-5-phosphate (the active form of vitamin B6) is the cofactor for aromatic L-amino acid decarboxylase (AADC), which converts 5-HTP to serotonin and L-DOPA to dopamine. B6 status modulates monoamine biosynthesis capacity but does not amplify St John's Wort's reuptake-inhibition effect; the combination is supportive (substrate availability), not synergistic.
Standard NRV-tier B6 supplementation (1.4 mg/day adult NRV) is well below any therapeutic threshold. Higher-dose B6 (>10 mg/day chronically) carries its own peripheral neuropathy concern documented in the EFSA opinion. Camden's vitamin-b6 carries the upper-limit detail.
Evidence: B6 cofactor role for monoamine synthesis is well-established; direct trial evidence for B6 + St John's Wort combination on mood is absent. UK Article 13 authorised claim: "Vitamin B6 contributes to normal psychological function". [6]
Doses studied: 1.4-10 mg/day vitamin B6 (within NRV range) alongside standardised St John's Wort. Higher B6 doses are not advised because of peripheral neuropathy risk.
Vitamin B1 (Thiamine)
Moderate evidenceB-complex cluster — B1 / B6 / B12 / folate are the energy-metabolism + nervous-system core.
B1 (thiamine) cofactor for pyruvate dehydrogenase / α-ketoglutarate dehydrogenase + transketolase; B6 (PLP) for amino acid metabolism. Mechanism complementary across energy + amino-acid axes.
Evidence: UK Article 13.1 energy-metabolism + nervous-system claims for both. [6]
Doses studied: 1.4 mg B1 + 1.4 mg B6 daily (UK NRV).
Vitamin B2 (Riboflavin)
Moderate evidenceB-complex cluster — B2 + B6 energy-metabolism + nervous-system support.
B2 (riboflavin) FAD / FMN cofactor; B6 (PLP) cofactor. Mechanism complementary across redox + amino-acid axes.
Evidence: UK Article 13.1 claims both. [6]
Doses studied: 1.4 mg B2 + 1.4 mg B6 daily.
Vitamin B5 (Pantothenic Acid)
Moderate evidenceB-complex cluster — B5 / B6 energy + adrenal-cortex cofactor framing.
B5 (pantothenic acid) is component of CoA + ACP — cofactor for steroid hormone synthesis + fatty-acid synthesis. UK Article 13.1 mental-performance + steroid-hormone-synthesis claim. B6 amino-acid metabolism.
Evidence: UK Article 13.1 claims both. [6]
Doses studied: 6 mg B5 + 1.4 mg B6 daily.