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 own editorial team graded each health claim below on the strength of the published evidence — trials weighed with Cochrane RoB 2, systematic reviews with AMSTAR 2, under the CEGA method. 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
- At a glance
- What people use it for
- How it works
- Common myths
- Common online questions
- The official position
- Authorised UK claims
- What the guidance says
- Camden's evidence review
- Safety, interactions & who should avoid it
- How to take it
- How to spot quality
- Commonly combined with
- Related ingredients
- Sources
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"
UK regulatory landscape
UK regulatory tier: Food supplement
EFSA claim status
Thiamine is an Annex-listed nutrient with authorised Article 13.1 claims; not a botanical-on-hold ingredient.
UK regulatory rules evolve. This summary is editorial — businesses should consult regulatory counsel; consumers should consult their pharmacist or GP.
🩺 What the guidance says
What UK and international health bodies say. Guidance leads; Camden’s own evidence review follows below.
NHSConditional
Vitamins and minerals — B vitamins and folic acid (thiamine, vitamin B1)
The NHS states that adults need about 1 mg of thiamine a day for men and 0.8 mg a day for women, and that thiamine cannot be stored in the body so it is needed in the diet every day. It says you should be able to get all the thiamine you need from a varied and balanced diet — good sources include peas, some fresh fruit such as bananas and oranges, nuts, wholegrain breads and fortified breakfast cereals. On supplements, the NHS notes that taking 100 mg or less a day is unlikely to cause harm, framing routine high-dose supplementation as unnecessary for most people.
NICERecommends
NICE Clinical Knowledge Summaries — Alcohol — problem drinking
NICE Clinical Knowledge Summaries describe thiamine supplementation as part of the primary-care management of people who misuse alcohol: oral thiamine is offered to those who are malnourished, at risk of malnourishment, or in acute withdrawal, while injected (parenteral) thiamine is used where Wernicke's encephalopathy is suspected or being prevented in higher-risk situations. The summary frames thiamine here as a prescribing decision made by a clinician to prevent a serious neurological complication — not as routine over-the-counter self-care.
BNFRecommends
BNF — Thiamine (NHS prescribing information)
GB-NHCConditional
Great Britain nutrition and health claims (NHC) register
The Great Britain nutrition and health claims register lists four authorised function claims for thiamine: it contributes to normal energy-yielding metabolism, normal functioning of the nervous system, normal psychological function, and the normal function of the heart. These claims may be used only where a product supplies at least 15% of the nutrient reference value (at least 0.165 mg per serving) and the wording follows the register. No claim is authorised for energy "boosting", stress, fatigue beyond the regulated wording, or any disease use.
EFSARecommends
EFSA — Dietary reference values: advice on thiamin (vitamin B1)
EFSA set a population reference intake for thiamine of 0.1 mg per megajoule of energy intake (about 0.9–1.1 mg a day for most adults), applying the same energy-based value to children and during pregnancy and lactation on the basis that the relationship between thiamine need and energy need is similar across groups. EFSA's positive scientific opinions on thiamine function also underpin the authorised health claims. These opinions substantiate the regulated claims and reference intakes rather than recommend any particular supplemental dose or product.
SOCIETY-OTHERConditional
British Dietetic Association — Supplements (Food Fact Sheet)
The British Dietetic Association, the UK professional body for dietitians, advises a food-first approach: most people who eat a varied, balanced diet do not need supplements, and they are worth considering mainly for defined groups or where intake or absorption is genuinely inadequate. It cautions against assuming that more is better and suggests taking professional advice before using high-dose products. Applied to thiamine, this supports obtaining it from food for the general population, with supplementation reserved for people at higher risk of deficiency.
🔬 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
EvidencestrongThiamine 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
EvidencelimitedSmall 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)
EvidencelimitedBenfotiamine, 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: Magnesium Complex 120 Capsules
Sources
Numbered references cited above plus general authoritative reading. Citations in the body link to the matching number here.
How to read these sources:
- Tier 1 (UK authoritative): NHS, NICE, BNF, EFSA, FSA, GB NHC Register, SACN, MHRA.
- Tier 2 (primary literature): peer-reviewed RCTs cited by PMID.
- Tier 3 (mechanistic): in-vitro / animal-model literature — interpret with caveat.
- NHS — Vitamins and minerals: B vitamins and folic acid
- Great Britain nutrition and health claims (NHC) register
- NICE CKS — Alcohol — problem drinking
- BNF — Thiamine
- EFSA — Dietary reference values: advice on thiamin (vitamin B1)
- NHS Specialist Pharmacy Service — Using and prescribing thiamine in alcohol dependence
- NHS — conditions › insect bites and stings