Thiamine (Vitamin B1)

One 150ml glass of 100% grapefruit juice delivers 6% while one half of a medium fresh grapefruit offers 8% of the Reference Intake (RI) for thiamine.*

What is Thiamine?

Thiamine, 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 Thiamine

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

Foods High in Thiamine

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

Thiamine Requirements

Very little thiamine is stored in the body, and because it is used up quickly by the body, frequent consumption of thiamine from the diet is necessary.

Thiamine needs increase during breastfeeding,1-3 and intake strongly affects the amount of this vitamin in breast milk.3 Requirements for thiamine also increase during:1-5

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

Thiamine Deficiency

Thiamine 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 thiamine can affect the cardiovascular, muscular, digestive, and nervous systems.1-3


Thiamine was the first B vitamin that scientists discovered, hence the name, B1.1,2

Learn more about the health benefits of fresh Florida Grapefruit and Florida Grapefruit Juice.

*Reference Intake: Based on a 2000 calorie diet. Information is not intended for labelling food in packaged form. Nutrient values may vary based on variety of citrus fruit and place of origin. Check with your citrus vendor for additional information.