What’s the upper safe dosage for thiamine from supplements?

What's the maximum safe dosage for thiamine (vitamin B1)?

Although the recommended daily intake for thiamine (vitamin B1) is 1.2 mg, there isn’t an upper safe dosage. Even daily doses of 5 mg are considered pretty safe. Adverse effects may occur when we take extremely high thiamine dosages of more than 500 mg for long periods of time.

What does thiamine do to the body?

Thiamine is a water-soluble B-vitamin. It’s also known as vitamin B1.

Thiamine is crucial for energy metabolism. It’s involved in glucose, amino acid, and lipid metabolism. Thus, people who want to lose weight should get adequate amounts of thiamine daily.

Moreover, thiamine is important for the synthesis of certain hormones and for the proper activity of certain enzymes.[1,2]

Severe thiamine deficiency may cause memory loss, visual disturbances, and weak muscles. Additionally, it may affect the nervous and cardiovascular system.

What’s the recommended daily dosage?

The recommended daily intake for thiamine is 1.2 mg for men and 1.1 mg for women, respectively.

Children and teenagers need lower dosages.

Only pregnant and lactating women need higher doses. They should get at least 1.4 mg of thiamine a day. 

What’s the upper safe dosage for thiamine (vitamin B1)?

Actually, the body can store only small amounts of thiamine. Hence, we should get thiamine from food or supplements every day.

In fact, there aren’t reports of severe adverse effects from high thiamine dosages of 50 mg. Neither from foods, nor supplements. Thus, the Food and Nutrition Board hasn’t established an upper day limit for thiamine.[3]

Moreover, high doses above 5 mg aren’t absorbed as effectively. Excess thiamine is excreted through urine.

But, there are thiamine (or vitamin B1) supplements which contain doses up to 500 mg. This dose is hundreds of times higher than the recommended daily intake. Even these dosages aren’t supposed to cause any adverse effect.[4]

But, extremely high doses for a long time could have adverse effects. Further studies are needed.

Certainly, you should consult your physician before taking any dietary supplement containing thiamine.

When should we get high doses of thiamine from supplements?

Healthy people who follow a well-balanced diet can get more than enough thiamine from foods.

But, obesity, poor diet, alcohol abuse, excessive carbohydrate consumption, major trauma, surgery, diabetes and other diseases may increase the risk of thiamine deficiency. In these cases, people may benefit from taking high dosages of thiamine, which only supplements can provide. The recommended daily dose isn’t enough.[5]

Additionally, calcium and magnesium deficiency negatively affects thiamine levels in the body!

Diuretics may also cause thiamine depletion.[6]

You can find a wide variety of thiamine supplements on Amazon.

Adverse effects of extremely high doses of thiamine

In rare cases of extremely high dosages of thiamine from supplements, people have reported adverse effects such as sensation of warmth, sweating, itching and discoloration of the skin, and allergic reactions.[7]