Vitamin B1 (Thiamine)
Thiamine, also called vitamin B1, is a vitamin the body uses to turn food into energy and to keep the nervous system working normally. It dissolves in water, so the body holds only a small store and needs a little from food every day. Most people in the UK get enough from a normal varied diet — by law, bread and flour are fortified with thiamine — so routine supplements are rarely needed. Shortfalls are mainly seen with heavy alcohol use or conditions that affect how food is absorbed. UK food supplements may carry authorised claims for energy, the nervous system, the heart and psychological function when they provide enough thiamine.
Camden Medicals editorial · Last reviewed 2 May 2026 · Next review May 2027
- 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
- Typical daily dose
- A normal UK diet supplies the reference intake. Everyday supplement doses are commonly 1–10 mg/day. Clinical replacement (for example, Wernicke prophylaxis or treatment) is much higher and is usually given by injection — a medical decision, not a food-supplement use.
- Top use evidence
- Strong
On this page
What it is
Thiamine is one of the eight B vitamins. The body uses it to help release energy from the food you eat and to keep the nervous system working normally. Because it dissolves in water and is not stored in large amounts, a small daily intake from food is needed.
You get thiamine from a wide range of everyday foods — fortified bread and flour, pork, peas and other pulses, nuts, wholegrains, and fortified breakfast cereals. In the UK, fortifying white and brown flour with thiamine is required by law under the Bread and Flour Regulations, which is one reason severe thiamine deficiency is uncommon in the general population. Where deficiency does occur, it is usually linked to heavy alcohol use (poor diet plus reduced absorption), conditions that affect how food is absorbed, severe pregnancy sickness (hyperemesis gravidarum), or after weight- loss (bariatric) surgery.
Common supplement forms are thiamine hydrochloride and thiamine mononitrate, which behave the same way for everyday food-supplement use. Benfotiamine is a fat-soluble synthetic relative of thiamine with higher oral absorption that has mostly been studied in research and specialist settings. Supplement-grade material is well-characterised; quality differences are mostly about purity and the other ingredients in the capsule.
At a glance
- Vitamin B1 helps the body release energy from food and keeps the nervous system working normally.
- Most people in the UK get enough from a normal diet — bread and flour are fortified with thiamine by law — so routine supplements are rarely needed.
- Authorised UK supplement claims (at ≥15 % of the nutrient reference value): contributes to normal energy-yielding metabolism, normal functioning of the nervous system, normal psychological function, and the normal function of the heart.
- Serious deficiency is uncommon but important: it is linked to heavy alcohol use and can lead to Wernicke-Korsakoff syndrome, a medical emergency managed by the NHS — not something to self-treat.
What people use it for
Adults with low thiamine intake — restrictive diets, low-meat / low-pulse, alcohol misuse
Multiple authorised Article 13.1 claims at ≥15 % NRV (≥0.165 mg). Supplemental thiamine returns intake to target. [2]
Popular, not provenInsufficientPeople at clinical risk of Wernicke-Korsakoff syndrome — chronic alcohol misuse, hyperemesis, post-bariatric, refeeding
Clinical thiamine replacement is a medical decision (often parenteral high-dose Pabrinex). Routine OTC supplementation is not the same as the clinical pathway. [3]
Some evidenceStrongAthletes / high-energy-demand contexts
Marketing energy benefit beyond authorised wording is unsupported. Authorised "contributes to normal energy-yielding metabolism" wording applies and is the regulated framing. [2]
Popular, not provenInsufficient
How it works
TPP-dependent enzymes catalyse the oxidative decarboxylation of pyruvate (entering the TCA cycle) and α-ketoglutarate (mid-TCA), plus the transketolase reaction in the pentose phosphate pathway (NADPH and ribose-5-phosphate generation). Acute deficiency impairs ATP production in tissues with high glucose dependence — the heart and central nervous system are most vulnerable, hence the cardiac (wet beriberi) and neurological (Wernicke-Korsakoff) presentations of deficiency.
Common myths
Myth"Thiamine is a stress vitamin you need extra of when busy."
RealityThiamine demand rises modestly with carbohydrate intake. UK diet ordinarily supplies the NRV. Deficiency is a clinical diagnosis, not a wellness condition.
Myth"Thiamine prevents mosquito bites."
RealityA persistent folk belief without trial evidence. NHS / WHO mosquito-bite guidance is DEET, picaridin, oil of lemon-eucalyptus, or permethrin-treated clothing. [7]
Common online questions
Synthesised from the questions UK shoppers most often ask online about Vitamin B1 (Thiamine). Each answer is editorial and links to its evidence in the Sources list below.
Do I need a thiamine supplement?
Most adults eating a UK-mixed diet do not. Thiamine deficiency is a clinical diagnosis associated with alcohol misuse, malabsorption, bariatric surgery, or hyperemesis. Routine supplementation is not on NHS preventive guidance. [1]
Thiamine HCl vs mononitrate vs benfotiamine — which?
For routine food-supplement use the two crystalline forms (HCl, mononitrate) are interchangeable. Benfotiamine has higher oral bioavailability but is mostly used in research / specialist contexts (diabetic-neuropathy trials).
⚖️ The official position
What may lawfully be claimed about Vitamin B1 (Thiamine) in Great Britain. This is a regulatory position, not an evidence grade.
A health claim is authorised in Great Britain.
“Thiamine contributes to normal energy-yielding metabolism”
“Thiamine contributes to normal functioning of the nervous system”
“Thiamine contributes to normal psychological function”
“Thiamine contributes to the normal function of the heart”
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.
4 authorised claims — show / hide
- "Thiamine contributes to normal energy-yielding metabolism"
- "Thiamine contributes to normal functioning of the nervous system"
- "Thiamine contributes to normal psychological function"
- "Thiamine contributes to the normal function of the heart"
🔬 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.
Thiamine deficiency / beriberi / Wernicke-Korsakoff syndrome
StrongEvidencestrongThiamine is a defined essential nutrient, and a clear shortfall produces a recognised clinical picture with established NHS treatment pathways (for example, parenteral thiamine such as Pabrinex for suspected Wernicke's encephalopathy). This is the well-evidenced ground: NICE Clinical Knowledge Summaries and the BNF set the clinical framework, and the evidence that correcting a true deficiency matters is strong. It is a clinical pathway, not a reason for routine over-the-counter supplementation in people who are not deficient. [3]
Cardiovascular outcomes in heart failure
LimitedEvidencelimitedSmall trials of higher-dose thiamine in people with heart failure who also had low blood thiamine have reported improvements in heart pumping measures. The studies were small and the question remains open, so this is not a general-population use; any role would be a clinical decision in people with confirmed low thiamine.
Diabetic nerve pain (benfotiamine)
LimitedEvidencelimitedBenfotiamine, a fat-soluble relative of thiamine, has been studied for diabetic nerve symptoms with mixed results. The evidence is early and it is a specialist consideration, not a first-line approach; UK diabetes and neuropathy care is led by NICE guidance.
Safety
Thiamine is generally very well tolerated at oral supplement doses. Excess is rapidly renally cleared. Acute hypersensitivity to high-dose IV thiamine is documented in clinical settings; this is not relevant to oral food-supplement use.
Talk to your pharmacist or GP first if you:
- You are pregnant or breastfeeding — supplemental at NRV is appropriate.
- You have suspected Wernicke-Korsakoff symptoms (acute confusion, ataxia, ophthalmoplegia, particularly in alcohol-misuse context) — this is a clinical emergency, not a self-treatment scenario.
Common side effects: No common side-effect profile at oral supplement doses.
Pregnancy and breastfeeding
The UK reference intake for thiamine rises only slightly in the last third of pregnancy (UK COMA reference nutrient intake), and a varied diet usually meets it. Severe pregnancy sickness (hyperemesis gravidarum) is a recognised risk for thiamine deficiency and is managed clinically. Talk to your midwife or GP before starting any supplement in pregnancy.
The UK reference intake for thiamine is modestly higher during breastfeeding (UK COMA reference nutrient intake), reflecting losses in breastmilk, and is usually met by a varied diet. Talk to your pharmacist, midwife or GP before starting a supplement while breastfeeding.
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 thiamine hypersensitivity.
Drug interactions
- No clinically significant interactions at oral supplement doses.
This is not an exhaustive list. Always tell your prescriber and pharmacist about every supplement you take.
Common side effects
- Generally very well tolerated at oral supplement doses.
Rare side effects
- Hypersensitivity to parenteral high-dose thiamine — clinical-setting concern.
How to take it
- Typical supplemental range
- A normal UK diet supplies the reference intake. Everyday supplement doses are commonly 1–10 mg/day. Clinical replacement (for example, Wernicke prophylaxis or treatment) is much higher and is usually given by injection — a medical decision, not a food-supplement use.
- Timing
- No specific timing requirement.
How to spot quality
Look for
- Form named — thiamine HCl, thiamine mononitrate, or benfotiamine.
- NRV percentage stated.
- GMP-certified manufacture.
Red flags
- Generic "vitamin B1" with no form named.
- Marketing implies fatigue elimination or "stress recovery" beyond the authorised wording.
Where Camden lands · meets the bar
Camden Medicals does not currently sell a standalone thiamine SKU. Thiamine appears as an adjunct active in a B-complex supplement (1.4 mg thiamine per capsule, 127 % NRV) and a ginkgo-with-B-vitamins supplement (1.1 mg thiamine per capsule, 100 % NRV). Both deliver claim-eligible thiamine doses and satisfy the encyclopaedia look-for bar (form named, NRV stated). A standalone thiamine SKU is not high priority given UK dietary sufficiency in the general population.
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.
Vitamin B6
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. [2]
Doses studied: 1.4 mg B1 + 1.4 mg B6 daily (UK NRV).
Vitamin B12
Moderate evidenceB-complex cluster — B1 + B12 nervous-system function.
Both UK Article 13.1 nervous-system function authorised. Mechanism complementary.
Evidence: UK Article 13.1 claims both. [2]
Doses studied: 1.4 mg B1 + 2.5 µg B12 daily (UK NRV).
Magnesium
Moderate evidenceEnergy-metabolism cluster — B1 PDH + αKGDH cofactor + magnesium ATP-binding cofactor.
B1 enzyme cofactor; magnesium ATP-Mg cofactor in same energy-metabolism reactions. UK Article 13.1 energy-metabolism + psychological-function claims for both.
Evidence: UK Article 13.1 claims authorised. [2]
Doses studied: 1.4 mg B1 + 200-400 mg magnesium daily.
Found in Camden: Aurifera™ Magnesium Complex 120 Capsules