Thiamin (Vitamin B1)

One 8-ounce glass of 100% grapefruit juice delivers 8% while one half fresh grapefruit offers 4% of the recommended Daily Value for thiamin.*

What is Thiamin?

Thiamin, also called vitamin B1, is an essential nutrient that is associated with the action of many of the body’s enzymes and in the conversion of food into energy.1

Benefits of Thiamin

Thiamin is a vital player in energy metabolism, which means it is involved in the growth, development, and function of cells.1,2,3 Thiamin may also play a role in supporting cognition and nervous system health.1,2

Foods High in Thiamin

Thiamin is naturally found in many foods including beans, meat, nuts, and citrus fruit and juice.

Thiamin Requirements

Very little thiamin is stored in the body, and because it is used up quickly by the body, frequent consumption of thiamin from the diet is necessary.1,2 Thiamin needs increase during breastfeeding,1-3 and intake strongly affects the amount of this vitamin in breast milk.3 Requirements for thiamin also increase during:1-5

  • Strenuous activity
  • Pregnancy and breastfeeding
  • Acute illness or fever
  • Recovery after surgery

Thiamin Deficiency

Thiamin deficiency is rare. It is more common in people with specific medical conditions including alcoholism, Crohn’s and other digestive diseases, and anorexia.1-3 Deficiency in thiamin can affect the cardiovascular, muscular, digestive, and nervous systems.1-3


Pink text reading "Did You Know" with a pink question mark

Thiamin was the first B vitamin scientists discovered, hence the name B1.1


* Daily Value: Based on a 2000 calorie diet. FDA rounding rules applied when calculating percent DV based upon 2018 rules. Information is not intended for labeling food in packaged form. Nutrient values may vary based on brand or product types.