Thiamin (B1)

What is thiamin?

Vitamin B1, or thiamin, is an important nutrient that supports cellular reactions throughout our bodies. As a water-soluble vitamin, thiamin can be easily cleared from the body, and is thus not stored in large amounts. Since our bodies cannot produce thiamin, we must get this nutrient through our diet.

Why we need it

Thiamin serves as a coenzyme (a substance required by an enzyme to carry out a chemical reaction) for many different metabolic processes. For instance, thiamin is a coenzyme for pyruvate dehydrogenase and alpha ketoglutarate dehydrogenase, which are enzymes involved in energy production.² Additionally, thiamin is a coenzyme for transketolase, an enzyme involved in the metabolism of sugar.² In this way, thiamin allows our bodies to produce energy and process the sugar we get from foods.

Thiamin is also important for brain health. It is involved in the synthesis of neurotransmitters such as serotonin and acetylcholine, which are critical for mood, memory, and overall cognitive function.³ Further, thiamin helps produce myelin, a substance that coats our brain cells, protecting them from damage and helping electrical signals travel more efficiently through the brain.³

Where it’s found

Thiamin is found in a variety of foods, including both animal-based and plant-based foods.^{1, 2} Examples of thiamin-rich foods include:

Pork
Organ meats
Poultry
Eggs
Fish
Beans
Lentils
Nuts and seeds
Whole grains

Thiamin can also be taken as a supplement, either by itself or as part of a multivitamin.

Daily requirements

The Recommended Dietary Allowance for thiamin (i.e. the amount that is likely to meet the needs of most healthy people) is 1.2 milligrams (mg) per day for male adults (aged 19 years and up) and 1.1 mg per day for female adults.⁴ Thiamin requirements increase to 1.4 mg per day for women who are pregnant or lactating.⁴

Thiamin deficiency

Given the many important functions of thiamin, being deficient in this vitamin can reduce our ability to produce energy, metabolize nutrients, and maintain good brain health. Thiamin deficiency can cause beriberi, a disorder that mainly affects the heart and the brain. There are two major forms of beriberi: dry beriberi, which affects the nervous system, and wet beriberi, which affects the cardiovascular system. Symptoms of dry beriberi include feelings of weakness, pain, or numbness in the feet.² Symptoms of wet beriberi include swelling, rapid breathing, and shortness of breath.²

Additionally, severe thiamin deficiency may lead to Wernicke-Korsakoff’s syndrome, a condition characterized by cognitive issues such as confusion, memory loss, irritability, and mood changes.²

Thiamin deficiency is rare in developed countries, as most people get enough thiamin through food.³ Nonetheless, certain individuals may be at higher risk for thiamin deficiency. For example, people with alcoholism, cancer, chronic kidney disease, obesity, or diabetes may be more likely to develop thiamin deficiency.²

Can you get too much thiamin?

Thiamin does not appear to cause any adverse effects, even when consumed in high amounts.² For this reason, there is currently no Tolerable Upper Intake Level (i.e., a maximum amount of a nutrient that is considered safe) established for thiamin.⁴

Fun facts

There are certain compounds (called tannins) found in coffee and tea that may inactivate thiamin.² That said, drinking excessive amounts of these beverages may interfere with your body’s ability to absorb thiamin.

A major source of thiamin is grains that have been enriched or fortified with thiamin (meaning thiamin is added to these products after processing). Because of this, populations that rely heavily on processed, non-enriched grains like white rice may be at a higher risk for thiamin deficiency.5 One way to help ensure you are getting enough thiamin is to choose whole grains, or breads and cereals that are labeled “enriched” or “fortified.”