What Happens to Your Body if You Don't Get Enough Thiamine?

December 22, 2025 •

3 min read

According to the National Institutes of Health, the body can only store about 20 days' worth of thiamine at any given time, making a consistent dietary intake essential. Thiamine, or vitamin B1, is vital for converting food into energy and supporting nerve and heart health.

Quick Summary

Thiamine deficiency can significantly affect the nervous system, heart, and brain, potentially leading to conditions like nerve damage, heart failure, and severe disorders such as Wernicke-Korsakoff syndrome and beriberi.

Key Points

Thiamine's role is critical for energy conversion: Thiamine helps convert carbohydrates into energy, essential for nerve and heart function.
Deficiency starts with subtle symptoms: Early signs like fatigue and irritability are often vague, making detection difficult.
Beriberi is a severe form: Untreated deficiency can lead to beriberi, which affects either the heart (wet) or the nerves (dry).
Wernicke-Korsakoff syndrome is a severe neurological issue: This disorder involves acute brain problems and chronic memory loss.
Chronic alcohol use is a major risk factor: Alcohol affects how the body uses thiamine.
Early treatment helps reverse effects: Timely thiamine supplements can reverse many effects, but long-term damage may be permanent.
Prevention is via diet: Eating foods high in thiamine is the best way to prevent deficiency.

The Role of Thiamine and Early Warning Signs

Thiamine (vitamin B1) is a vital coenzyme involved in metabolism. A consistent supply is needed because the body doesn't store large amounts. Low levels impair energy production, particularly affecting the brain and heart. Initial symptoms are often subtle.

Early signs may include:

Fatigue: Persistent tiredness.
Irritability and Mood Changes: Can occur due to reduced brain energy.
Loss of Appetite: Leading to potential weight loss.
Digestive Discomfort: Nausea, vomiting, abdominal pain, and constipation.

Progression to Severe Thiamine Deficiency: Beriberi

If mild deficiency is untreated, it can advance to beriberi. This is often associated with diets lacking thiamine, like polished white rice. Beriberi has forms affecting different body systems.

Dry Beriberi

This type primarily impacts the nervous system. Nerve damage often begins in the extremities.

Symptoms can include:

Peripheral Neuropathy: A tingling or numb sensation in the hands and feet.
Muscle Weakness: Developing as nerve damage worsens.
Ataxia: Difficulty with coordination.

Wet Beriberi

This form affects the cardiovascular system and requires urgent medical attention. The heart has to work harder.

Signs may include:

Cardiomegaly: Enlarged heart and rapid heartbeat.
Peripheral Edema: Swelling in the legs and feet.
High-Output Heart Failure: The heart struggles to pump enough blood, which can be fatal if untreated.

The Most Severe Neurological Complication: Wernicke-Korsakoff Syndrome

Wernicke-Korsakoff Syndrome (WKS) is a severe, chronic brain disorder linked to long-term thiamine deficiency, often seen in individuals with chronic alcoholism. It involves two components.

Wernicke's Encephalopathy: An acute, serious brain condition causing confusion, eye movement problems, and unsteadiness. Prompt treatment is vital.
Korsakoff's Syndrome: A chronic memory disorder that can develop after Wernicke's encephalopathy. It is marked by severe short-term memory loss.

Long-Term Effects and Complications

Ignoring thiamine deficiency can lead to irreversible damage, especially to the nervous system. Some nerve issues might be permanent. Korsakoff syndrome can result in lasting disability. The cardiovascular system can also suffer long-term effects. Early diagnosis and treatment with supplements are crucial.

Thiamine Deficiency Comparison


Symptom Category	Mild Deficiency	Severe Deficiency (Beriberi)	Wernicke-Korsakoff Syndrome
Neurological	Irritability, poor memory, fatigue	Peripheral neuropathy, muscle weakness, ataxia	Confusion, ataxia, eye movement problems, memory loss
Cardiovascular	Early signs often subtle	Rapid heart rate, enlarged heart, edema	Tachycardia, low blood pressure, heart failure
Digestive	Loss of appetite, nausea	Constipation, abdominal pain	Nausea, vomiting, abdominal discomfort
Severity and Prognosis	Generally reversible with supplementation	Reversible if treated early, but can be fatal	Irreversible brain damage possible, especially for memory

How to Prevent Thiamine Deficiency

Preventing deficiency involves consuming a diet rich in thiamine. The recommended daily intake is 1.2 mg for adult men and 1.1 mg for adult women. Sources include whole grains, pork, and certain fish. Supplements might be necessary if dietary intake isn't sufficient or if there are increased needs. Individuals with risk factors like alcoholism or bariatric surgery should seek medical advice. For more details on diet and risk factors, see the {Link: National Institutes of Health Fact Sheet https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional/}.

Conclusion

A lack of thiamine can range from minor symptoms to serious, life-threatening conditions like wet beriberi and lasting brain damage from Wernicke-Korsakoff syndrome. Since the body doesn't store much thiamine, regular intake from food or supplements is essential to prevent severe issues affecting the nervous, heart, and immune systems. Recognizing symptoms early and getting prompt medical help are key to a better outcome and avoiding permanent damage.

Frequently Asked Questions

Initial signs are often subtle and can include fatigue, irritability, loss of appetite, poor memory, and abdominal discomfort.

Dry beriberi affects the nervous system, causing nerve damage and muscle weakness. Wet beriberi impacts the heart and circulatory system, leading to an enlarged heart, rapid heart rate, and fluid retention.

This serious brain disorder is caused by severe thiamine deficiency. It includes Wernicke's encephalopathy (acute confusion and eye problems) and Korsakoff's syndrome (chronic severe memory loss).

Individuals with chronic alcohol use disorder face the highest risk. Other factors include bariatric surgery, HIV/AIDS, kidney disease, chronic vomiting, and certain diuretics.

Diagnosis is typically based on examination, symptoms, blood tests measuring transketolase activity, and response to thiamine treatment.

Many effects can be reversed with early treatment. However, severe or chronic cases, like Wernicke-Korsakoff syndrome, can result in permanent nerve and brain damage.

Good sources include pork, fish, whole grains, fortified cereals, beans, lentils, and sunflower seeds.