Why Your Body Needs Vitamin B1 (Thiamine)

Jess says: Like many doctors, I was trained to look for conditions caused by a severe deficiency of vitamin B1; particularly Wernicke’s encephalopathy, but I failed to understand the wide range of lesser symptoms like low energy, mood and sleep problems which can also be caused by a vitamin B1 deficiency.

Over the years, however, I have helped my patients to improve these symptoms multiple times after finding that their B1 was low. It’s worth considering a multivitamin with good levels of thiamine, to help maintain these levels if you think you may be deficient.

Vitamin B1 (also called thiamin or thiamine), is a water-soluble vitamin (this means that it is carried in the bloodstream and eliminated in the urine), which can be destroyed by heat, such as cooking or processing.

Thiamine is a critical vitamin for the brain and nervous system, and also very important for the heart, muscles and for good gut health.

thiamine (B1 deficiency) can be very serious

Although rare in the modern world, very low vitamin B1 levels can cause a condition called beriberi. This can affect the cardiovascular system (heart and blood vessels) causing heart failure, increased heart rate, shortness of breath and difficulty breathing and swelling of the ankles and legs.

A B1 deficiency also affects the nervous system, creating a loss of sensation in the hands and feet, unsteady walking and poor balance, pain in the muscles and eye problems, such as nystagmus (a repeated flicking movement of the eyes). Extreme deficiency worsens into a brain condition called Wernicke’s encephalopathy, which causes memory loss, confusion, psychosis and confabulation (making up words). Low energy, weight loss, depression, fatigue and sleep disorders may all be mild signs of B1 deficiency, which can be corrected with supplements.1

Patients who drink too much alcohol, have been on an extreme diet or have severe vomiting or diarrhoea can inadvertently find themselves at risk of vitamin B1 deficiency. ‘At risk’ patients are those with a poor diet or with severe diarrhoea, those who regularly drink too much alcohol, have gut problems that affect the absorption of nutrients, hyperemesis gravidarum (severe vomiting in pregnancy) or after stomach surgery or chemotherapy. 

thiamine also has an important role in sepsis

Studies show that your chance of dying from sepsis, a life-threatening infection that has dramatically increased in recent years, is higher if your thiamine levels are low.2 Thiamine is part of a promising protocol for sepsis, showing amazing results alongside intravenous vitamin C. Thiamine given to patients with sepsis appears to reduce the risk of kidney failure that can result from the infection.3

B1 may help in treating depression, too

Thiamine, given alongside an antidepressant, improved symptoms of depression faster, and produced more stability in mood than without it.4 As early thiamine deficiency can cause symptoms of depression, it is worth considering in people who experience consistently low moods.

it’s also great for treating period pain and PMS

Two trials of female students showed a large significant improvement in the physical and mental symptoms of PMS, when taking vitamin B1 during their menstrual cycle, with no side effects.5, 6

Period pain (dysmenorrhoea) was significantly improved in high school students taking thiamine.7, 8

if you have diabetes, consider taking thiamine supplements

Blood sugar and insulin levels of patients with borderline or high blood sugars improved after taking high doses of thiamine for six weeks.9, 10 High doses of thiamine also reduced high blood pressure in patients with diabetes, and so could help prevent heart and circulation complications11 and kidney complications.12 Giving B1 with B12 improved nerve pain from diabetes and lessened the number of painkillers needed, in one study.13

feeling fatigued?

A trial of thiamine supplements for four weeks was given to patients with fatigue (low energy). They showed a significant improvement in their energy levels.14 Thiamine has also been shown to help recovery from fatigue after exercise (even if you are not deficient),15 so it may be useful when doing a lot of sport or gym work, for faster recovery times. 

thiamine supplements may also help with brain function, aiding memory loss and reaction time

Patients given thiamine supplements had improved reaction speeds and felt more clear-headed and energetic in a study of young adults.16 In patients who had previously been addicted to cocaine, thiamine supplements improved memory accuracy.17

other benefits of thiamine include:

  • Giving high doses of thiamine to those who are alcoholic or alcohol-dependent has been shown to increase the chance of recovery and reduce emotional symptoms.18
  • Along with other vitamins B6 and B12, B1 has been shown to help reduce blood markers related to mild cognitive impairment (memory loss) and Alzheimer’s19 and improve symptoms of Alzheimer’s at high dose.20
  • A small study of children with autism showed a clinical improvement in symptoms when given thiamine supplements for two months.21
  • Thiamine supplements significantly reduced spotting and heavier bleeding in women who had a copper coil IUD fitted, when 100mg was taken daily for three months.22
  • Itching and pain from herpes lesions (cold sores) were reduced by injecting thiamine into them, with no side effects.23
  • Patients with heart failure who were given thiamine for four weeks had a significant improvement in their heart function.24,25
  • Patients on dialysis are particularly at risk of thiamine deficiency and can have serious brain-related symptoms due to this.26
  • Chronic epilepsy patients who received thiamine supplements had a significant improvement in brain function and cognitive ability.27
  • A genetic degenerative disease in children, basal ganglia disease, which causes movement problems is significantly helped by giving thiamine.28

what’s the best way to get my thiamine levels checked?

It can be difficult to get the right test for thiamine levels. It’s important to measure: erythrocyte thiamine pyrophosphate – this is the active form of vitamin B1, measured inside the blood cells (best test results should be greater than 70nmol/L), or by doing an erythrocyte transketolase activity blood test, which measures the activity of thiamine (best test results should be under 1.15). Results over 1.15 would suggest a thiamine deficiency. Measuring vitamin B1 in plasma is a less accurate test. 

how much thiamine do I need?

The recommended daily amount of thiamine is 1.1mg daily (the amount needed to prevent deficiency). However, it is very safe at much higher levels and trials use anywhere from 25mg-3g daily. Excess thiamine is excreted in the urine, and many trials have been done using thiamine supplements in both pregnancy and whilst breastfeeding.

what are the best sources of vitamin B1?

nutritional yeast: 1 tablespoon/4.8mg. This is a powder form of the yeast, Saccharomyces cerevisiae. (It tastes great on popcorn, sprinkle it over and shake well – savoury, healthy and delicious)

yeast extract spread. This can include spreads such as Marmite, Vegemite and brewer’s yeast. Take 1 tsp/0.6mg daily

macadamia nuts: ½ cup, raw = 0.8mg

green garden peas: 1 cup of cooked green peas = 0.4mg

wild Atlantic Salmon: 1 cooked piece = 0.6mg

pistachio nuts – ½ cup dried, roasted = 0.6mg

which thiamine supplement is best?

Thiamine hydrochloride (HCl) is quickly and easily absorbed, to increase thiamine levels29 if yours are low. Thiamine supplements are regarded as very safe.30 Vitamins and minerals work well together, so it is often a good idea to take a high-quality daily multivitamin with a good level of B vitamins, like our one. multivitamin, or a good vitamin B complex.


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  2. Donnino MW, Andersen LW, Chase M, Berg KM, Tidswell M, Giberson T, Wolfe R, Moskowitz A, Smithline H, Ngo L, Cocchi MN; Center for Resuscitation Science Research Group. Randomized, Double-Blind, Placebo-Controlled Trial of Thiamine as a Metabolic Resuscitator in Septic Shock: A Pilot Study Crit Care Med. 2016 Feb;44(2):360-7. doi: 10.1097/CCM.0000000000001572. PMID: 26771781; PMCID: PMC4754670.
  3. Moskowitz A, Andersen LW, Cocchi MN, Karlsson M, Patel PV, Donnino MW. Thiamine as a Renal Protective Agent in Septic Shock. A Secondary Analysis of a Randomized, Double-Blind, Placebo-controlled Trial Ann Am Thorac Soc. 2017 May;14(5):737-741. doi: 10.1513/AnnalsATS.201608-656BC. PMID: 28207287; PMCID: PMC5427738.
  4. Ghaleiha A, Davari H, Jahangard L, Haghighi M, Ahmadpanah M, Seifrabie MA, Bajoghli H, Holsboer-Trachsler E, Brand S. Adjuvant thiamine improved standard treatment in patients with major depressive disorder: results from a randomized, double-blind, and placebo-controlled clinical trial Eur Arch Psychiatry Clin Neurosci. 2016 Dec;266(8):695-702. doi: 10.1007/s00406-016-0685-6. Epub 2016 Mar 16. PMID: 26984349.
  5. Abdollahifard S, Rahmanian Koshkaki A, Moazamiyanfar R. The effects of vitamin B1 on ameliorating the premenstrual syndrome symptoms Glob J Health Sci. 2014 Jul 29;6(6):144-53. doi: 10.5539/gjhs.v6n6p144. PMID: 25363099; PMCID: PMC4825494.
  6. Hosseinlou A, Alinejad V, Alinejad M, Aghakhani N. The effects of fish oil capsules and vitamin B1 tablets on duration and severity of dysmenorrhea in students of high school in Urmia-Iran TGlob J Health Sci. 2014 Sep 18;6(7 Spec No):124-9. doi: 10.5539/gjhs.v6n7p124. PMID: 25363189; PMCID: PMC4796395.
  7. Hosseinlou A, Alinejad V, Alinejad M, Aghakhani N. The effects of fish oil capsules and vitamin B1 tablets on duration and severity of dysmenorrhea in students of high school in Urmia-Iran Glob J Health Sci. 2014 Sep 18;6(7 Spec No):124-9. doi: 10.5539/gjhs.v6n7p124. PMID: 25363189; PMCID: PMC4796395.
  8. Gokhale LB. Curative treatment of primary (spasmodic) dysmenorrhoea Indian J Med Res. 1996 Apr;103:227-31. PMID: 8935744.
  9. Alaei Shahmiri F, Soares MJ, Zhao Y, Sherriff J. High-dose thiamine supplementation improves glucose tolerance in hyperglycemic individuals: a randomized, double-blind cross-over trial Eur J Nutr. 2013 Oct;52(7):1821-4. doi: 10.1007/s00394-013-0534-6. Epub 2013 May 29. PMID: 23715873.
  10. González-Ortiz M, Martínez-Abundis E, Robles-Cervantes JA, Ramírez-Ramírez V, Ramos-Zavala MG. Effect of thiamine administration on metabolic profile, cytokines and inflammatory markers in drug-naïve patients with type 2 diabetes  Eur J Nutr. 2011 Mar;50(2):145-9. doi: 10.1007/s00394-010-0123-x. Epub 2010 Jul 21. PMID: 20652275. 
  11. Alaei-Shahmiri F, Soares MJ, Zhao Y, Sherriff J. The impact of thiamine supplementation on blood pressure, serum lipids and C-reactive protein in individuals with hyperglycemia: a randomised, double-blind cross-over trial Diabetes Metab Syndr. 2015 Oct-Dec;9(4):213-7. doi: 10.1016/j.dsx.2015.04.014. Epub 2015 Apr 29. Erratum in: Diabetes Metab Syndr. 2016 Jan-Mar;10(1):61. PMID: 25982678.
  12. Riaz S, Skinner V, Srai SK. Effect of high dose thiamine on the levels of urinary protein biomarkers in diabetes mellitus type 2 J Pharm Biomed Anal. 2011 Mar 25;54(4):817-25. doi: 10.1016/j.jpba.2010.11.008. Epub 2010 Nov 13. Erratum in: J Pharm Biomed Anal. 2011 Aug 25;56(1):139. PMID: 21130593.
  13. Mimenza Alvarado A, Aguilar Navarro S. Clinical Trial Assessing the Efficacy of Gabapentin Plus B Complex (B1/B12) versus Pregabalin for Treating Painful Diabetic Neuropathy J Diabetes Res. 2016;2016:4078695. doi: 10.1155/2016/4078695. Epub 2016 Jan 17. PMID: 26885528; PMCID: PMC4739211.
  14. Kim KM, Kim MJ, Song SW, Cho DY, Park KC, Yang SW, Kim YS, Kim KS. Efficacy and Safety of “URSA Complex” in Subjects with Physical Fatigue: A Multicenter, Randomized, Double-blind, Placebo-controlled Trial Chin Med J (Engl). 2016 Jan 20;129(2):129-34. doi: 10.4103/0366-6999.173432. PMID: 26830981; PMCID: PMC4799537.
  15. Suzuki M, Itokawa Y. Effects of thiamine supplementation on exercise-induced fatigue Metab Brain Dis. 1996 Mar;11(1):95-106. doi: 10.1007/BF02080935. PMID: 8815395.
  16. Benton D, Griffiths R, Haller J. Thiamine supplementation mood and cognitive functioning Psychopharmacology (Berl). 1997 Jan;129(1):66-71. doi: 10.1007/s002130050163. PMID: 9122365.
  17. Easton CJ, Bauer LO. Beneficial effects of thiamine on recognition memory and P300 in abstinent cocaine-dependent patients Psychiatry Res. 1997 May 30;70(3):165-74. doi: 10.1016/s0165-1781(97)00024-3. PMID: 9211578.
  18. Manzardo AM, Pendleton T, Poje A, Penick EC, Butler MG. Change in psychiatric symptomatology after benfotiamine treatment in males is related to lifetime alcoholism severity Drug Alcohol Depend. 2015 Jul 1;152:257-63. doi: 10.1016/j.drugalcdep.2015.03.032. Epub 2015 Apr 8. PMID: 25908323; PMCID: PMC4550087.
  19. Rommer PS, Fuchs D, Leblhuber F, Schroth R, Greilberger M, Tafeit E, Greilberger J. Lowered Levels of Carbonyl Proteins after Vitamin B Supplementation in Patients with Mild Cognitive Impairment and Alzheimer’s Disease Neurodegener Dis. 2016;16(3-4):284-9. doi: 10.1159/000441565. Epub 2015 Nov 21. PMID: 26587902
  20. Meador K, Loring D, Nichols M, Zamrini E, Rivner M, Posas H, Thompson E, Moore E. Preliminary findings of high-dose thiamine in dementia of Alzheimer’s type J Geriatr Psychiatry Neurol. 1993 Oct-Dec;6(4):222-9. doi: 10.1177/089198879300600408. PMID: 8251051.
  21. Lonsdale D, Shamberger RJ, Audhya T. Treatment of autism spectrum children with thiamine tetrahydrofurfuryl disulfide: a pilot study Neuro Endocrinol Lett. 2002 Aug;23(4):303-8. PMID: 12195231.
  22. Jafari A, Abedi P, Sayahi M, Torkashvand R. The effect of vitamin B1 on bleeding and spotting in women using an intrauterine device: a double-blind randomised controlled trial Eur J Contracept Reprod Health Care. 2014 Jun;19(3):180-6. doi: 10.3109/13625187.2014.893425. Epub 2014 Apr 17. PMID: 24738933.
  23. Xu G, Lv ZW, Xu GX, Tang WZ. Thiamine, cobalamin, locally injected alone or combination for herpetic itching: a single-center randomized controlled trial Clin J Pain. 2014 Mar;30(3):269-78. doi: 10.1097/AJP.0b013e3182a0e085. PMID: 23887347.
  24. Schoenenberger AW, Schoenenberger-Berzins R, der Maur CA, Suter PM, Vergopoulos A, Erne P. Thiamine supplementation in symptomatic chronic heart failure: a randomized, double-blind, placebo-controlled, cross-over pilot study Clin Res Cardiol. 2012 Mar;101(3):159-64. doi: 10.1007/s00392-011-0376-2. Epub 2011 Nov 5. PMID: 22057652.
  25. Shimon I, Almog S, Vered Z, Seligmann H, Shefi M, Peleg E, Rosenthal T, Motro M, Halkin H, Ezra D. Improved left ventricular function after thiamine supplementation in patients with congestive heart failure receiving long-term furosemide therapy Am J Med. 1995 May;98(5):485-90. doi: 10.1016/s0002-9343(99)80349-0. PMID: 7733128.
  26. Hung SC, Hung SH, Tarng DC, Yang WC, Chen TW, Huang TP. Thiamine deficiency and unexplained encephalopathy in hemodialysis and peritoneal dialysis patients Am J Kidney Dis. 2001 Nov;38(5):941-7. doi: 10.1053/ajkd.2001.28578. PMID: 11684545.
  27. Botez MI, Botez T, Ross-Chouinard A, Lalonde R.Thiamine and folate treatment of chronic epileptic patients: a controlled study with the Wechsler IQ scale  Epilepsy Res. 1993 Oct;16(2):157-63. doi: 10.1016/0920-1211(93)90030-b. PMID: 8269914.
  28. Tabarki B, Alfadhel M, AlShahwan S, Hundallah K, AlShafi S, AlHashem A. Treatment of biotin-responsive basal ganglia disease: Open comparative study between the combination of biotin plus thiamine versus thiamine alone Eur J Paediatr Neurol. 2015 Sep;19(5):547-52. doi: 10.1016/j.ejpn.2015.05.008. Epub 2015 Jun 12. PMID: 26095097.
  29. Smithline HA, Donnino M, Greenblatt DJ. Pharmacokinetics of high-dose oral thiamine hydrochloride in healthy subjects BMC Clin Pharmacol. 2012 Feb 4;12:4. doi: 10.1186/1472-6904-12-4. PMID: 22305197; PMCID: PMC3293077.
  30. Thiamin – Health Professional Fact Sheet 


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