Vitamin B1: Research · Nutrient Desk

Can high doses reduce fatigue?

A Danish crossover trial enrolled 40 people with inactive inflammatory bowel disease and severe unexplained fatigue. Four weeks of 600–1,800 mg thiamin daily reduced fatigue scores more than placebo. This small, disease-specific trial does not establish an everyday energy benefit for healthy people. 1

Physical EnergyToo little evidence

The promising fatigue result applies to a specific patient group. 1

Did a lower maintenance dose work?

In the open-label extension, 300 mg daily for 12 weeks did not maintain a fatigue benefit compared with no thiamin. The initial improvement therefore does not establish a successful long-term regimen. 2

Effects by health goal

Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.