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Vitamin B1 (Thiamine)

An essential vitamin whose deficiency is dangerous and whose supplement case, beyond deficiency, is thin.

Thiamine (vitamin B1) is required to turn carbohydrates into energy and to keep nerves functioning. We grade Vitamin B1 (Thiamine) C- on evidence and C for worth-it at about $4-10 per month.

C-

Evidence

C

Worth it

Typical cost: $4-10/month

What it does

Thiamine (vitamin B1) is required to turn carbohydrates into energy and to keep nerves functioning. It is sold as thiamine itself and as benfotiamine, a fat-soluble derivative that raises blood levels higher and carries most of the research claims (nerve pain, cognition).

What the research says

  • Treats and prevents thiamine deficiency, which is dangerous and sometimes fatal

    Evidence: strong. Deficiency causes beriberi and Wernicke-Korsakoff syndrome. Risk concentrates in alcohol use disorder, malnutrition, bariatric surgery, and severe vomiting. Treatment is urgent, clinical, and established; that is a medical use, not a wellness one.

  • No benefit for heart failure beyond correcting deficiency

    Evidence: moderate. The largest meta-analysis (7 randomized trials, 274 patients) found no significant effect on ejection fraction, walking distance, NT-proBNP, or symptom class. An earlier two-trial pooling (38 patients) reported a small ejection fraction gain; the bigger synthesis supersedes it.

  • Benfotiamine may slow cognitive decline in early Alzheimer's disease or MCI

    Evidence: emerging. One phase IIa trial (Gibson et al., 2020; 70 participants, 12 months, 300 mg twice daily): the primary cognitive outcome missed significance (ADAS-Cog decline 43 percent lower, p=0.125); a secondary rating improved (p=0.034). A pilot signal awaiting a real trial.

  • Studied for diabetic nerve pain with mixed results

    Evidence: weak. Benfotiamine trials in diabetic peripheral neuropathy split between short-term positives and longer nulls. Nothing here is settled in either direction.

Thiamine is an essential vitamin whose deficiency is genuinely dangerous, and almost everything beyond that sentence is thin. The heart-failure literature, the most-tested supplement claim, pools to no benefit beyond correcting deficiency. The benfotiamine cognitive pilot is one small trial whose primary outcome missed. The diabetic-neuropathy trials are mixed and small. For a generally nourished adult, there is no outcome evidence at any dose, and the vitamin's excellent safety record is a reason it is harmless to take, not a reason it helps.

The week's longevity and biohacking news.

This grade for Vitamin B1 (Thiamine) rests on the record above. When a new result changes that record, the grade changes with it, and the Thursday email is where the change lands first: the week's longevity and biohacking news, in plain English, linked back to the reasoning on this page.

The week's longevity and biohacking news. Every story graded against the evidence. Free. Unsubscribe anytime.

Every grade follows a published rubric, and sponsors never change one. When the evidence moves a grade, Thursday is where you hear it first, before you renew a stack that stopped earning its cost.

Is it worth it?

C

Evidence (C-) sits below the leaderboard floor, so the worth-it grade is capped at C+ however inexpensive it is; the derived value lands at C. About $7 a month at a common dose. Derived from the October 2026 worth-it model.

Typical cost

$4-10/month

Common form, not a brand recommendation

Dosage context established

The daily requirement is about 1.1 to 1.2 mg. Retail thiamine products commonly carry 50 to 100 mg, and the fat-soluble derivative benfotiamine is sold and studied at 150 to 600 mg/day. No dose is established for healthy adults, because no benefit in healthy adults has been established at any dose. Suspected deficiency is a medical problem: Wernicke's is treated with high-dose intravenous thiamine, not a capsule from a shelf.

Worth-it leaderboard

Vitamin B1 (Thiamine) sits outside the worth-it top 20.

Vitamin B1 (Thiamine) sits outside the current top 20 on the gated leaderboard. The leaders below clear an evidence floor of B- before price counts at all, so cheap alone never earns a rank.

  1. 1ACreatine evidence A-~$5-10/mo
  2. 2ACaffeine evidence B+~$5-10/mo
  3. 3AVitamin D evidence B~$5-8/mo

See the full worth-it leaderboard →

When the evidence moves a grade, this ranking moves with it. Thursday is where you hear it first.

Safety notes

Among the safest supplements known. No upper limit has been set: excess is excreted, and oral thiamine has essentially no documented toxicity at retail doses. Rare allergic reactions are reported, almost entirely with intravenous use. The real risk around thiamine is the opposite one: missing a true deficiency, which can cause permanent brain injury. New confusion, unsteady gait, or abnormal eye movements in someone at risk is an emergency, not a supplement decision.

Longevity Lab Report

Vitamin B1 (Thiamine) news. Graded when it happens.

The grade on this page stays free. The email carries the news on vitamin b1 (thiamine): expert moves, dose changes, and what is working, in plain English every Thursday.

Changelog

Last updated 2026-10-23

  • 2026-10-23|Graded from the deficiency literature, the heart-failure trial meta-analyses (null beyond correcting deficiency), and the single benfotiamine cognitive pilot in early Alzheimer's disease and MCI, whose primary outcome missed significance.
  • 2026-10-23|Also listed under energy and cognition, matching this record's graded findings on deficiency fatigue and the benfotiamine pilot.