{"ok":true,"entry":{"slug":"vitamin-b1","kind":"supplement","name":"vitamin b1","aliases":["thiamine","thiamin"],"brands_sg":["California Gold Nutrition","NOW Foods","Life Extension","Thorne","Nature's Way"],"class":"vitamin","tags":["energy","cognitive"],"use_for":"energy metabolism · growth and function of cells","use_after":"no timing rule · short half-life, so a steady supply matters","use_duration":null,"take_with":"water · active transport at food doses, diffusion at high","pros":["rda is small — 1.2 mg men / 1.1 mg women","no ul — no adverse effects reported at 50 mg/day+","excess is excreted in the urine"],"cons":["absorption falls sharply at intakes above 5 mg","diabetes/heart-failure trials: too small to conclude","sg caps b1 in health supplements at 100 mg/day"],"dose_note":"rda 1.2 mg men / 1.1 mg women (19+), 1.4 mg in pregnancy and lactation; multis typically give about 1.5 mg; no ul, but the fnb notes absorption drops at intakes above 5 mg and that excessive intakes 'could have adverse effects'; benfotiamine is a synthetic derivative that is not water soluble and is converted to thiamin in the body; hsa's limit for singapore health supplements is 100 mg/day","dosage":{"ul":null,"unit":"mg","fda_dv":1.2,"rda_ai":"1.2 mg men · 1.1 mg women","ul_status":"none_established","population":"general adult","hsa_max_daily":100},"ul_status":"none_established","sg_class":null,"cautions":["alcohol dependence — the most common cause of deficiency in industrialised countries; a doctor's check, not self-treatment","past bariatric surgery — severe deficiency from malabsorption is a listed risk; ask your doctor","older adults — 20–30% show lab signs of some deficiency; worth a doctor's check","diabetes — plasma thiamin runs lower; the sheet calls the trial evidence too small to draw conclusions"],"clashes":[{"src":["nih_ods_b1_drugs"],"note":"linked to lower thiamin levels, possibly deficient, through urinary loss","with":"furosemide (lasix)"},{"src":["nih_ods_b1_drugs"],"note":"case reports of beriberi or wernicke's encephalopathy during treatment","with":"fluorouracil (5-fu, adrucil)"}],"sources":[{"id":"nih_ods_b1_intro","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Introduction","quote":"Thiamin (or thiamine) is one of the water-soluble B vitamins. It is also known as vitamin B1 … This vitamin plays a critical role in energy metabolism and, therefore, in the growth, development, and function of cells","accessed":"2026-08-27"},{"id":"nih_ods_b1_absorb","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Introduction (absorption)","quote":"Ingested thiamin from food and dietary supplements is absorbed by the small intestine through active transport at nutritional doses and by passive diffusion at pharmacologic doses","accessed":"2026-08-27"},{"id":"nih_ods_b1_store","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Introduction (storage, half-life)","quote":"Humans store thiamin primarily in the liver but in very small amounts. The vitamin has a short half-life, so people require a continuous supply of it from the diet","accessed":"2026-08-27"},{"id":"nih_ods_b1_rda","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Table 1 RDAs + DV note","quote":"Table 1: Recommended Dietary Allowances (RDAs) for Thiamin … 19–50 years 1.2 mg 1.1 mg 1.4 mg 1.4 mg … 51+ years 1.2 mg 1.1 mg … The DV for thiamin is 1.2 mg for adults and children age 4 years and older","accessed":"2026-08-27"},{"id":"nih_ods_b1_supp","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Dietary supplements","quote":"Multivitamin/mineral supplements with thiamin typically provide about 1.5 mg thiamin … The most commonly used forms of thiamin in supplements are thiamin mononitrate and thiamin hydrochloride … Benfotiamine is not water soluble and is converted to thiamin in the body","accessed":"2026-08-27"},{"id":"nih_ods_b1_risk","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Groups at risk (alcohol, older adults)","quote":"chronic alcohol use disorders appear to be the most common cause of thiamin deficiency … Up to 20%–30% of older adults have laboratory indicators that suggest some degree of thiamin deficiency","accessed":"2026-08-27"},{"id":"nih_ods_b1_risk2","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Groups at risk (bariatric surgery, diabetes)","quote":"Bariatric surgery for weight loss is associated with some risks, including severe thiamin deficiency due to malabsorption … thiamin levels in plasma are up to 76% lower in people with type 1 diabetes than in healthy volunteers","accessed":"2026-08-27"},{"id":"nih_ods_b1_health","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Thiamin and health (diabetes, heart failure)","quote":"Well-designed studies with larger sample sizes and longer durations are required to determine whether thiamin supplements can reduce glucose levels in patients with diabetes … More research is needed to determine whether thiamin supplements might benefit people with heart failure","accessed":"2026-08-27"},{"id":"nih_ods_b1_ul","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Health risks from excessive thiamin","quote":"The body excretes excess amounts of thiamin in the urine. Because of the lack of reports of adverse effects from high thiamin intakes (50 mg/day or more) from food or supplements, the FNB did not establish ULs for thiamin","accessed":"2026-08-27"},{"id":"nih_ods_b1_ul2","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Health risks from excessive thiamin (cont.)","quote":"the apparent lack of toxicity may be explained by the rapid decline in absorption of thiamin at intakes above 5 mg … in spite of the lack of reported adverse events, excessive intakes of thiamin could have adverse effects","accessed":"2026-08-27"},{"id":"nih_ods_b1_drugs","url":"https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/","label":"NIH ODS — Thiamin (Health Professional), updated February 9, 2023 — Interactions with medications","quote":"Research has linked the use of furosemide to decreases in thiamin concentrations, possibly to deficient levels, as a result of urinary thiamin loss … several cases of beriberi or Wernicke's encephalopathy resulting from treatment with this drug [fluorouracil]","accessed":"2026-08-27"},{"id":"hsa_hs_guidelines","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines GL-CHPB-3-001 Rev. No. 020 (January 2026), s4.8 general-adult limits, Table 4 Vitamins Limits + List of Health Claims rows 23, 56, 80","quote":"Table 4: Vitamins Limits … Vitamin B1 100mg … Contribute to normal energy-yielding metabolism … Biotin, vitamin B1, B2, B3, B5, B6, C, D … Maintain/support energy production … Vitamin B1, B5 … Maintain/support nervous system function … Biotin, vitamin B1, B2, B3, B6","accessed":"2026-08-27"},{"id":"hsa_prohibited_2025","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev. 001 (October 2025), Annex A row 108","quote":"108. Vitamin B1 Restricted use in HS and TM Maximum Daily Dose When for oral use by general adult population, the maximum recommended daily dose should not provide more than 100mg","accessed":"2026-08-27"},{"id":"fda_dv","url":"https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels","label":"FDA — Daily Value on the Nutrition and Supplement Facts Labels (Reference Guide: Daily Values for Nutrients), content current as of 03/05/2024","quote":"Thiamin 1.2mg … DVs are the recommended amounts of nutrients to consume or not to exceed each day","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/vitamin-b1-thiamine","label":"iHerb Singapore — Vitamin B1 Thiamine category page (default order), first listings","quote":"1 - 19 of 19 results … California Gold Nutrition, Benfotiamine with Thiamine, 250 mg … NOW Foods, B-1, 100 mg … Life Extension, Mega Benfotiamine … Thorne, B-Complex #12 … Nature's Way, Vitamin B1, 100 mg","accessed":"2026-08-27"}],"brand_certs":[{"brand":"Thorne","example":null,"programme":"NSF Certified for Sport","matching_products":0,"brand_total_certified":66}],"updated_at":"2026-08-30T17:59:36.026222+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}