Thiamine (Vitamin B1) Deficiency
Your body stores only a few weeks’ worth of thiamine. Run low and the brain, nerves and heart suffer. It’s most common with heavy drinking, and it’s the reason Australian bread flour has had thiamine added since 1991.
Who’s at risk
- Heavy or long-term alcohol use: up to 80% of people with alcohol dependence become deficient
- Weight-loss (bariatric) surgery, especially with vomiting
- Severe vomiting, including in pregnancy (hyperemesis), and eating disorders
- Older adults in care, people with poor intake or long hospital stays
- Long-term furosemide (a fluid tablet), some chemotherapy, and dialysis
Symptoms
- Early: tiredness, poor appetite, irritability, poor memory, muscle weakness
- Beriberi: numb, tingling or weak legs (nerve damage); or heart failure with swollen legs and breathlessness
- Wernicke’s encephalopathy (an emergency): confusion, unsteady walking and abnormal eye movements or double vision. Without treatment, up to 1 in 5 people die
- Korsakoff syndrome: severe, lasting memory loss, often with made-up memories (confabulation)
Treatment
- Mild deficiency: thiamine tablets and better nutrition.
- Suspected Wernicke’s: high-dose thiamine by injection in hospital, straight away. Doctors don’t wait for blood results.
- Anyone who drinks heavily or is malnourished should have thiamine before a glucose drip, as sugar can tip borderline deficiency into Wernicke’s.
- Many people with Korsakoff syndrome improve only partly, so prevention matters.
Food sources
- Wholegrains, fortified breads and cereals, pork, fish, legumes, nuts and seeds.
- Adults need about 1.1–1.2 mg a day (1.4 mg in pregnancy and breastfeeding).
- Thiamine is lost when food is boiled and the water is thrown out.
See your GP if
- You drink heavily and want to cut down: ask about thiamine as well as support to reduce drinking
- You’ve had weight-loss surgery and have vomiting, numbness or memory changes
- You have numb or weak legs without a clear cause
Call 000 if someone who drinks heavily or is malnourished becomes confused, very unsteady or has new problems with their eyes. Wernicke’s encephalopathy needs urgent treatment.
Weird history
- In the 1890s, Dutch doctor Christiaan Eijkman noticed chickens fed polished white rice developed a beriberi-like illness, while those fed brown rice didn’t. He shared the 1929 Nobel Prize.
- Beriberi is thought to come from a Sinhalese phrase meaning “I can’t, I can’t”.
Common questions
What causes thiamine deficiency?
Mostly heavy alcohol use, which cuts intake, absorption and storage. Other causes include weight-loss surgery, prolonged vomiting, eating disorders, poor diet and some medicines.
What is Wernicke’s encephalopathy?
A medical emergency caused by severe thiamine deficiency. It causes confusion, unsteady walking and eye movement problems. Treatment is urgent high-dose thiamine by injection.
What is Korsakoff syndrome?
A long-lasting memory disorder that can follow Wernicke’s encephalopathy. People struggle to form new memories and may fill gaps with made-up memories. Recovery is often only partial.
Why is thiamine added to bread in Australia?
Since 1991, flour for bread has been enriched with thiamine to reduce Wernicke-Korsakoff syndrome. Australia still has higher rates than many similar countries.
Is too much thiamine harmful?
No upper limit has been set. Excess is passed in urine, and no harm has been reported at normal supplement doses.
Helpful resources
- Healthdirect: Vitamins and mineralsPlain-English Australian Government guide. Free.
- Dietitians AustraliaFind an Accredited Practising Dietitian near you.
Evidence and more information
- NIH Office of Dietary Supplements: Thiamin
- MJA 1998: Wernicke-Korsakoff syndrome in Australia and thiamine fortification
- Nobel Prize: Christiaan Eijkman
- Nutrient Reference Values for Australia and New Zealand (Eat for Health)
maladywise.com/thiamine/