10 Most Common Symptoms of B1 Deficiency

These factors may increase your risk of being B1 deficient:

  • Alcohol dependence
  • Old age
  • Diabetes
  • Bariatric surgery
  • Dialysis
  • High-dose diuretic use

Many people don’t realize that they have a deficiency, as many of the symptoms are subtle and often overlooked.

Here are 10 signs and symptoms of thiamine deficiency:

1. Loss of Appetite

One common early symptom of thiamine deficiency is a loss of appetite, or anorexia. Scientists believe that thiamine plays an important role in the regulation of satiety. It helps control the “satiety center” located in the hypothalamus of the brain. When deficiency occurs, normal action of the “satiety center” is altered, causing the body to feel satiated or full, even when it may not be. This can result in a lack of appetite.

2. Fatigue

Fatigue may occur gradually or suddenly. It can range from a slight decrease in energy to extreme exhaustion, likely depending on the severity of deficiency. However, considering the vital role thiamine plays in converting food into fuel, it’s no surprise that fatigue and lack of energy is a common symptom of deficiency.

3. Irritability

Irritability is the feeling of agitation and frustration. When you are irritable, you often become upset quickly. Irritability can be caused by various physical, psychological and medical conditions. An irritable mood is noted to be one of the first symptoms of thiamine deficiency. It may occur within days or weeks of deficiency. 

4. Reduced Reflexes

Thiamine deficiency can affect the motor nerves. If left untreated, the damage to your nervous system caused by thiamine deficiency could cause changes in your reflexes. Reduced or absent reflexes of the knee, ankle and triceps are often observed, and as deficiency progresses, it may affect your coordination and ability to walk

5. Muscle Weakness

Generalized muscle weakness is not uncommon, and its cause is often difficult to determine. Short-term, temporary muscle weakness happens to almost everyone at some point. However, persistent, long-standing muscle weakness without a clear cause or reason may be a sign of thiamine deficiency. In multiple cases, patients with thiamine deficiency have experienced muscle weakness. Furthermore, in these cases, muscle weakness greatly improved after thiamine re-supplementation.

6. Blurry Vision

Thiamine deficiency may be one of the many causes of blurry vision. Severe thiamine deficiency can cause swelling of the optic nerve, inducing optic neuropathy. This can result in blurry, or even loss of, vision. Multiple documented cases have linked blurry vision and vision loss to severe thiamine deficiency. Furthermore, patients’ vision improved significantly after supplementation with thiamine

7. Nausea and Vomitting

Although gastrointestinal symptoms are less common in thiamine deficiency, they can still occur. It’s not exactly understood why digestive symptoms may manifest with thiamine deficiency, but documented cases of gastrointestinal symptoms have been resolved after thiamine supplementation. Vomiting may be more common in infants with deficiency, as it was found to be a common symptom in infants who consumed a thiamine-deficient, soy-based formula.

8. Changes in Heart Rate

Not enough thiamine could result in a slower than normal heartbeat. Marked decreases in heart rate have been documented in studies involving thiamine-deficient rats. An abnormally slow heart rate as result of thiamine deficiency may cause increased fatigue, dizziness and a greater risk of fainting.

9. Delirium

Multiple studies have linked thiamine deficiency and delirium. Delirium is a serious condition that results in confusion, reduced awareness and the inability to think clearly. In severe cases, thiamine deficiency can cause Wernicke-Korsakoff syndrome, which involves two types of closely related brain damage It’s symptoms often include delirium, memory loss, confusion and hallucinations. 

10. Shortness of Breath

Given that thiamine deficiency can affect heart function, shortness of breath may occur, especially with exertion.This is because thiamine deficiency can sometimes lead to heart failure, which occurs when the heart becomes less efficient at pumping blood. This can ultimately result in fluid accumulation in the lungs, making it difficult to breathe.