What Is A Thiamine Deficiency?

Medically Reviewed by Melinda Ratini, MS, DO on September 13, 2023
Written by WebMD Editorial Contributor
4 min read

Vitamin B1, also known as thiamine, is an essential micronutrient. It helps the body function by taking energy from food and turning it into fuel for the brain, nerves, and heart. Thiamine is also needed for the body to process fats and proteins, but it is essential for processing carbohydrates like sugars and starches.

A thiamine deficiency can result in several health problems, including confusion, seizures, shortness of breath, brain disease, coma, and more.

Thiamine plays an important role in helping your body function well. Some of the biggest benefits of thiamine include:

  • Nervous system. Thiamin helps prevent complications in the nervous system, brain, muscles, heart, stomach, and intestines. 
  • Electrolytes. It is also involved in the flow of electrolytes into and out of muscle and nerve cells.
  • Disease. It helps prevent beriberi diseases, which involve disorders of the heart, nerves, and digestive system.
  • Energy. Thiamine is considered a form of vitamin B that is water-soluble. It helps to convert what you eat and drink into energy or glucose.
  • Organs. Thiamine vitamins are necessary for keeping the liver, skin, hair, and eyes healthy. They also play a role in the nervous system and are needed for good brain function.
  • Stress. The B vitamins are sometimes called anti-stress vitamins because they boost the body’s immune system during stressful times.

Foods rich in this vitamin include:

  • ‌Yeast
  • Legumes
  • Pork
  • Brown rice
  • Cereal
  • Pasta
  • Flour
  • Trout
  • Tuna
  • Eggs
  • Nuts and seeds

While fruit, vegetables, and dairy products are not very high in thiamine, they can become a substantial thiamine source when eaten in large amounts.

Thiamine can also be taken as a supplement, typically orally.

Thiamine deficiency is caused by not getting enough of this vitamin. This can occur in two ways: either too little thiamine is consumed or too much of it is lost. If you’re experiencing thiamine deficiency you’re likely to have one or a combination of these symptoms:

  • Ataxia. Ataxia is a degenerative disease of the nervous system. Many symptoms of Ataxia are similar to those of being drunk, such as slurred speech, stumbling, falling, and poor coordination.
  • Confusion. You may experience the inability to think or reason in a focused, clear manner.
  • Nystagmus. Nystagmus is a vision condition in which the eyes make repetitive, uncontrolled movements.
  • Irritability. Feelings of frustration or anger, often over seemingly small matters, may occur.
  • Seizure. A seizure is a burst of uncontrolled electrical activity between brain cells (also called neurons or nerve cells) that causes temporary abnormalities in muscle tone or movements (e.g. stiffness, twitching, or limpness).
  • Papilledema. Papilledema is a severe medical condition where the optic nerve at the back of the eye becomes swollen.
  • Short-term memory loss. This condition is when you forget things you heard, saw, or did recently.
  • Tachycardia. This condition results in a rapid heartbeat that may be regular or irregular but is out of proportion to age and exertion or activity level.
  • Mood changes. Mood swings refer to rapid changes in mood. The term may refer to minor or significant mood changes on a daily basis.
  • Edema. More commonly known as swelling, edema is puffiness caused by excess fluid trapped in the body's tissues.
  • Dyspnea. This condition results in shortness of breath. However, it can have causes that aren't due to underlying disease.
  • Sensory-Motor Polyneuropathy. This condition is a body-wide (systemic) process that damages nerve cells, nerve fibers, and nerve coverings. Damage to the covering of the nerve cell causes nerve signals to slow or stop.

Left untreated, or if a thiamine deficiency is critical, complications can be severe:

  • Deterioration of the heart’s ability to pump blood
  • Coma
  • Disease of the brain
  • Heart failure
  • Permanent nerve damage, which may limit sensation
  • Psychosis
  • Worsening of diabetic nerve damage

In some cases, thiamine deficiency can be life-threatening. Call 911 if you, or someone you are with, have any of these symptoms:

Several factors increase your risk of developing a thiamine deficiency. Because it is rare, most people with risk factors will not get thiamine deficiency. However, those who are experiencing the following may be more at risk:

  • ‌Alcoholism
  • Gastric bypass surgery
  • Genetic beriberi (inability to absorb thiamine)
  • Kidney disease
  • Starvation
  • Poor diet
  • No or limited access to nutritious foods

The only treatment for thiamine deficiency is thiamine supplementation and changes to any underlying dietary habits that may have caused the deficiency. Thiamine supplementation can be given orally or by injection, depending on the type and cause of the deficiency.

If identified early and treated promptly, most symptoms should resolve. People who have thiamine deficiency should receive long-term monitoring of their thiamine levels to ensure that the deficiency does not return.