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Vitamin B1 (Thiamin) - Deficiency Risk and Symptoms

2 min read

Nutrient Name

Vitamin B1 - otherwise known as Thiamin

Potential for deficiency

Very Common

A Vitamin B1 deficiency can happen due to numerous factors, such as over-dieting, abusing alcohol, liver disorders, and kidney dialysis. Those who consume large quantities of sweets, fizzy drinks, and highly processed foods can also be at a higher risk of deficiency. Thiamin deficiency is particularly widespread among alcoholics because chronic alcohol abuse lowers the quantity of Vitamin B1 (and other nutrients) that is absorbed by the body. 

What does Vitamin B1 do?

Vitamin B1 (thiamin) is one of 8 in the B-Vitamin family.  It helps the body convert carbohydrates into fuel (glucose) which the body uses to produce energy - it contributes to a normal energy-yielding metabolism. It also helps the body metabolise fats and protein. Thiamin also contributes to normal function of the immune system and heart.

The European Food Safety Authority (EFSA) confirms that clear health benefits have been established for the dietary intake of Thiamin (Vitamin B1) in contributing to: 

  • the normal function of the heart
  • normal carbohydrate and energy-yielding metabolism
  • the normal function of the nervous system
  • normal neurological development and function
  • normal psychological functions.

Food Sources

Pork, offal (organ meats), whole grains, brown rice, bran, Brewers yeast. yogurt, lean meats such as chicken and turkey, seafood, beans, peas, eggs, nuts and seeds.

Thiamin (Vitamin B1) is a water-soluble vitamin and as such, it is unlikely to reach toxic levels. There is little danger of thiamin toxicity when it is taken orally. 

Symptoms of deficiency

  • Headache
  • Nausea
  • Fatigue
  • Irritability
  • Depression
  • Abdominal discomfort
  • Cardiac failure
  • Muscle pain


A healthy balanced diet is the best way to consume all the nutrients we need. Sometimes however this isn't possible and then supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying any supplements or herbal medicines.