What Happens If Vitamin B1 Is Low? Thiamin Deficiency

1. Irritability and fatigue

Thiamin deficiency can cause mood changes, including irritability. Being irritable may be accompanied by fatigue.

Children with thiamin deficiencies frequently have increased irritability and discomfort.

2. Muscle and nerve abnormalities

Vitamin B1 deficiency, also called beriberi, can cause nerve damage or neuropathy. It can also cause muscle damage. There are two types of beriberi:

• Dry beriberi: Symptoms occur without heart failure
• Wet beriberi: Symptoms are accompanied by heart failure

Signs of dry beriberi include:

• Prickling (pins-and-needles) sensation
• Sensation within your toes
• Burning feeling on the feet that is most intense at night
• Leg cramps and discomfort
• Muscle atrophy and weakness (muscles get weaker and then deteriorate)
• Worsening of the symptoms that can affect the arms

Signs of wet beriberi include:

• Rapid heartbeat
• Dilation of the blood vessels
• Heart failure
• Unstable blood pressure
• Swelling in the leg
• Chest congestion
• Shock
• Death

3. Brain disorders

Thiamin deficiency can cause brain abnormalities, especially in cases of alcohol abuse. Brain abnormalities may exist without causing symptoms until something occurs that exacerbates the symptoms, such as excessive alcohol intake. 

Brain disorders can cause symptoms when an alcohol user receives carbohydrates intravenously. These symptoms are caused by the fact that these additional carbs increase the thiamin requirement. This brain disorder is known as Wernicke-Korsakoff disorder that is divided into two types:

• Wernicke encephalopathy results in confusion, apathy, difficulty walking, and eye issues with uncontrollable eye movements (nystagmus) and partial eye paralysis. If Wernicke encephalopathy isn't immediately treated, the symptoms can get worse, leading to coma or even death.
• Korsakoff psychosis can cause memory loss in current events, as well as confusion and the tendency to fabricate details to cover the gaps in memory (confabulation).

4. Tingling arms and legs

Itching and the sensation of prickliness or "pins and needles" in your legs and arms (paresthesia) can be a sign of severe beriberi or a warning sign of early thiamin deficiency. It usually occurs before widespread brain-related symptoms. 

Thiamin is essential for the proper functioning of the nerves that extend to your legs and arms, and insufficient thiamin in the body could lead to paresthesia. If left untreated, thiamin deficiencies can result in more severe damage to the nervous system. 

5. Loss of appetite

An atypical loss of appetite may be an early symptom of an existing thiamin deficiency. This can lead to unintentional weight loss.

One possible explanation for weight loss is that thiamin plays a crucial role in regulating hunger and satiety within the brain. Inadequate thiamin levels may disrupt these signals and leave you feeling full even when you are not.

This can lead to a lack of appetite and deprivation of vital nutrients.

6. Blurry vision

Because of the important role thiamin plays in maintaining nerve health, a deficiency could affect the optic nerves in your eyes.This can lead to swelling of the optic nerve, which can cause blurred vision. 

If left untreated, optic nerve damage can eventually lead to vision loss. Thiamin deficiency that causes blurry vision is, however, rare.A few small-scale studies have reported that supplements that correct thiamin deficiencies could dramatically enhance eyesight in these situations.

Thiamin deficiency is rare, especially in the U.S. However, low vitamin B1 levels may be related to:

• Poor intake of thiamin due to:
  • Diets primarily high in polished rice/processed grains
  • Chronic alcoholism
  • Parenteral nutrition without adequate thiamin supplementation
  • Gastric bypass surgery
  • Eating disorders
• Poor absorption due to:
  • Malnutrition
  • Gastric bypass surgery
  • Malabsorption syndromes
• Increased loss of thiamin due to:
  • Diarrhea
  • Chronic vomiting
  • Diuretic use
  • Renal replacement therapy
• Increased thiamin needs due to:
  • Pregnancy
  • Lactation
  • Hyperthyroidism
• Drugs such as diuretics