Thiamine (Vitamin B1)

Formulation

Thiamine is a naturally occurring part of many standard diets, but it may be purchased over the counter in tablet or capsule forms as dietary supplements too.^[1][2][3] More than one type of thiamine supplement is available on the market, however, including standard thiamine (thiamine HCl and thiamine mononitrate) and thiamine derivatives (benfotiamine, sulbutiamine, fursultiamine, and allithiamine).^[4][5] Thiamine derivatives are more commonly used in the treatment of thiamine deficiency, likely because they are considered to be more bioavailable than standard thiamine.^[4][6][7][8]

Thiamine taken orally as capsules or tablets is commonly reported in the evidence.^{[9][10][11][12][13][14][15][16][17][18]} Under clinical supervision, thiamine may also be administered intravenously, through a feeding tube or by intramuscular injection.^{[2][10][11][13][15][17][18][19][20][21][22][23]}

Range of dosages studied

Oral thiamine dosages used in studies range from 100 to 500 mg per day, commonly over a duration of about 2 months (ranging from 1 to 36 months).^{[9][10][12][13][14][16]}

Other considerations

Thiamine RDA

The longstanding recommended dietary allowance (RDA) for thiamine in adults is 1.1 to 1.2mg daily, though median dietary intake in the United States has been estimated at 2mg per day.^{[2][6][24][25]} Several tests exist for assessing thiamine status, but none of these alone is adequate for estimating individual thiamine requirements.^[3][24][25]

Thiamine UL

No tolerable upper intake level (UL) for thiamine exists, it is considered well tolerated and safe.^[2][3][25]