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Vitamin B1

Thiamine (Vitamin B1) is an essential vitamin involved heavily in glucose production. While not a common deficiency in an otherwise healthy diet and limited benefits when taken by a healthy subject, instances of high blood glucose and/or alcoholism can increase the need for this vitamin drastically.

Our evidence-based analysis on vitamin b1 features 18 unique references to scientific papers.

Research analysis led by Kamal Patel .
Reviewed by
Examine.com Team
Last Updated:

Things To Know & Note

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How to Take Vitamin B1

Recommended dosage, active amounts, other details

Thiamine supplements are usually taken at doses well above the RDA, such as 100-300mg, in instances where thiamine is considered to be deficient such as high blood sugar or high alcohol intake. When using thiamine at this dose timing does not matter much and either one dose can be taken in the morning or multiple doses throughout; thiamine does not need to be ingested with food to be absorbed.

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Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects vitamin b1 has on your body, and how strong these effects are.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-d Strong Very High See 2 studies
One study found a staggering reduction in symptoms with 100 mg of vitamin B1 daily. It wasn't clear what the baseline vitamin B1 status of the participants was. Another study found a notable benefit of 100 mg daily over 2 months, and also that the improvement was additive with calcium, with the combination being notably more potent than either separately. Much more research is needed.
grade-d Minor - See study
In instances where thiamine is deficient, replenishment of thiamine appears to cause a modest decrease in blood pressure.
grade-d - - See study
No changes of note in people with high blood sugar
grade-d - - See study
No significant changes in people with hyperglycemia
grade-d - - See study
No change noted in those with high blood sugar
grade-d - - See study
No change noted in people with high blood sugar
grade-d - - See study
No observed changes in a population with hyperglycemia

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Frequently Asked Questions about Vitamin B1

Do B vitamins increase the risk of getting cancer?
Recent evidence has linked B vitamins (specifically B6 and B12) to an increased risk of lung cancer in men, especially in smokers. Here, we analyze the study and interview the lead author, Dr. Theodore Brasky.

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Research Breakdown on Vitamin B1

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Thiamine is known to be reduced in the body in response to various conditions or drugs, most notably diabetes (where it may be reduced by 75-76% in both type I and type II diabetes[1]) and alcoholism.[2] These two conditions have different ways of reducing thiamine levels with alcoholism impairing the way low amounts of thiamine are absorbed (active transport)[2] whereas high blood glucose increase the rate of thiamine elimination through urine.[1]

Thiamine deficiency has also been noted in subjects with obesity with one study referencing a 15.5-29% rate of frequency[3] based on evidence from studies on subjects seeking bariatric surgery;[4][5] it was speculated that, beyond increase rate of thiamine elimination from high blood glucose, that a diet predominant in processed food and oils may be contributive since they lack thiamine.[3]

It has been noted,[3] in part due to a lack of long term stores of thiamine in the body and reliance on dietary intake, that thiamine replenishment in these instances may take as short as 2-3 weeks. However, as alcohol inhibits the mechanism responsible for absorption of low thiamine concentrations and not high concentrations[2] replenishment involves taking doses significantly above the RDA of 1.1-1.2mg.[6]

Both alcoholism and high blood glucose can increase the risk of thiamine deficiency, and as they do so in two different manners their risks may compound. Obesity is also seen as a risk factor

Benfotiamine and Sulbutiamine are two stand-alone supplements related to the thiamine molecule, with the former being a fat-soluble derivative and the latter two thiamine molecules bound together. While sulbutamine has drastically different properties, benfotiamine is claimed to be a pro-drug for thiamine (converting into thiamine after ingestion) with at least one study suggesting a 2.7-fold greater bioavailability when compared to thiamine HCl[7] and another claiming that only 40% of the oral dose is needed if aiming for the same circulating levels of thiamine after supplementation.[8]

Thiamine is investigated for interactions with blood pressure due to evidence in the spontaneously-hypertensive rat (SHR) line where thiamine administration reduced blood pressure associated with down-regulating (normalizing) abnormalities of a few genes in the renin-angiotensin system such as PAI-1, TGFβ-1, the AT-1 receptor and angiotensinogen.[1] There is also thought to be an additional link to hyperglycemia (high blood sugar) since high blood glucose an increase thiamine elimination in the urine[1] and one human study in subjects with liver cirrhosis found that repleting low levels of thiamine greatly helped both blood glucose and blood pressure levels.[10]

When tested in subjects with hyperglycemia, supplementation of 300mg thiamine (HCl) for six weeks appeared to reduce mean arterial pressure and diastolic blood pressure to a minor degree (2.3% and 4.3% respectively) when compared to placebo with no effect on systolic blood pressure or pulse.&spreference;

While a modest effect, it seems supplemental thiamine could help blood pressure in subjects who have high blood glucose

Thiamine is involved in the glucose synthesis pathway


  1. ^ a b c Thornalley PJ et al.. High prevalence of low plasma thiamine concentration in diabetes linked to a marker of vascular disease. Diabetologia. (2007)
  2. ^ a b c Hoyumpa AM Jr. Mechanisms of thiamin deficiency in chronic alcoholism. Am J Clin Nutr. (1980)
  3. ^ a b c Kerns JC1, Arundel C2, Chawla LS. Thiamin deficiency in people with obesity. Adv Nutr. (2015)
  4. ^ Flancbaum L et al.. Preoperative nutritional status of patients undergoing Roux-en-Y gastric bypass for morbid obesity. J Gastrointest Surg. (2006)
  5. ^ Carrodeguas L et al.. Preoperative thiamine deficiency in obese population undergoing laparoscopic bariatric surgery. Surg Obes Relat Dis. (2005)
  6. ^ Lonsdale D. A review of the biochemistry, metabolism and clinical benefits of thiamin(e) and its derivatives. Evid Based Complement Alternat Med. (2006)
  7. ^ Wada T et al.. A new thiamine derivative, S-benzoylthiamine O-monophosphate. Science. (1961)
  8. ^ Balakumar P et al.. The multifaceted therapeutic potential of benfotiamine. Pharmacol Res. (2010)
  9. ^ Hassan R, Qureshi H, Zuberi SJ. Effect of thiamine on glucose utilization in hepatic cirrhosis. J Gastroenterol Hepatol. (1991)
  10. Abdollahifard S, Rahmanian Koshkaki A, Moazamiyanfar R. The effects of vitamin B1 on ameliorating the premenstrual syndrome symptoms. Glob J Health Sci. (2014)
  11. Depeint F, et al. Mitochondrial function and toxicity: role of the B vitamin family on mitochondrial energy metabolism. Chem Biol Interact. (2006)
  12. Selhub J. Folate, vitamin B12 and vitamin B6 and one carbon metabolism. J Nutr Health Aging. (2002)
  13. Chen AC, et al. A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention. N Engl J Med. (2015)
  14. Brasky TM, White E, Chen CL. Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. J Clin Oncol. (2017)
  15. White E, et al. VITamins And Lifestyle cohort study: study design and characteristics of supplement users. Am J Epidemiol. (2004)
  16. Kim YI. Folate and colorectal cancer: an evidence-based critical review. Mol Nutr Food Res. (2007)
  17. Kok DE, et al. The effects of long-term daily folic acid and vitamin B12 supplementation on genome-wide DNA methylation in elderly subjects. Clin Epigenetics. (2015)
  18. Corbin JM, Ruiz-Echevarría MJ. One-Carbon Metabolism in Prostate Cancer: The Role of Androgen Signaling. Int J Mol Sci. (2016)