What Does Thiamine Deficiency Do to the Heart? The Impact of Vitamin B1 on Cardiovascular Health

October 24, 2025 •

4 min read

Approximately one in three people with congestive heart failure may have a thiamine deficiency, underscoring the critical link between this nutrient and cardiac function. As a vital cofactor for energy production, understanding what does thiamine deficiency do to the heart is crucial for at-risk individuals, as a severe lack can lead to a dangerous condition known as cardiac or 'wet' beriberi.

Quick Summary

A severe lack of thiamine, or vitamin B1, directly impairs cardiac energy metabolism, leading to a serious form of heart failure known as wet beriberi, characterized by impaired contractility and dilated cardiomyopathy.

Key Points

Impaired Energy Metabolism: Thiamine deficiency hinders the heart's ability to produce energy, leading to a state of cardiac energy starvation.
Wet Beriberi: The cardiovascular form of severe thiamine deficiency, which can progress from a high-output heart failure state to a weakened, low-output state.
Cardiomyopathy and Shock: Prolonged deficiency can cause dilated cardiomyopathy and, in acute cases (Shoshin beriberi), lead to life-threatening cardiogenic shock.
Endothelial Dysfunction: A lack of thiamine impairs the function of blood vessel linings, contributing to vascular inflammation and oxidative stress.
Reversible with Treatment: The cardiac effects of thiamine deficiency are often rapidly reversible with timely and appropriate thiamine supplementation.
High-Risk Populations: Individuals with chronic alcoholism, post-bariatric surgery, chronic diuretic use, or severe malnutrition are particularly vulnerable to thiamine deficiency.

The Role of Thiamine in Cardiac Function

Thiamine, commonly known as vitamin B1, is a water-soluble vitamin essential for numerous metabolic processes in the human body, particularly those involved in energy production. Its active form, thiamine pyrophosphate (TPP), acts as a critical cofactor for key enzymes involved in the metabolism of carbohydrates and branched-chain amino acids, including pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase. Since the heart is a highly active muscle with a constant, high demand for energy in the form of adenosine triphosphate (ATP), it is particularly vulnerable to thiamine depletion.

When thiamine levels are low, these vital enzymes function inefficiently, disrupting the heart's primary energy pathways. This leads to a severe energy deficit within the cardiac muscle, progressively impairing its ability to contract and pump blood effectively.

The Cardiovascular Consequences of Thiamine Deprivation

Thiamine deficiency's impact on the heart manifests most notably as 'wet beriberi,' a potentially fatal form of heart failure. The condition typically evolves through distinct stages:

Initial High-Output State: In the early stages, the body attempts to compensate for the cellular energy crisis and peripheral vascular changes. The deficiency leads to decreased systemic vascular resistance due to peripheral vasodilation, forcing the heart to beat faster and pump more blood to meet the body's needs. This results in a high-output cardiac state, presenting with a rapid heart rate, warm skin, and wide pulse pressure. Fluid retention also begins at this stage.
Progression to Low-Output Heart Failure: As the heart muscle is overworked and energy-deprived, it begins to weaken. The initially high-output state gives way to low-output heart failure, characterized by systolic dysfunction and reduced left ventricular ejection fraction. This leads to fluid accumulation in the legs and lungs, causing symptoms like shortness of breath and edema (swelling).
Acute Fulminant Cardiovascular Beriberi (Shoshin Beriberi): In its most severe and rapid form, wet beriberi can cause acute cardiogenic shock and imminent death. This is a medical emergency marked by hypotension, tachycardia, and lactic acidosis, and it can be rapidly fatal without immediate intervention.

The Cellular Mechanism Behind Cardiac Failure

The cardiac damage from thiamine deficiency is rooted in impaired cellular metabolism. As TPP activity declines, pyruvate and other metabolic intermediates build up, forcing the body to rely on less efficient anaerobic metabolism. This process generates lactic acid, contributing to lactic acidosis, a marker of the severe metabolic disruption.

Additionally, thiamine deficiency contributes to endothelial dysfunction. The endothelium, the lining of blood vessels, requires sufficient thiamine to function correctly. Its impairment exacerbates vascular and inflammatory problems, further increasing cardiovascular risk. Thiamine depletion also promotes oxidative stress, which damages endothelial cells and contributes to the overall vascular and cardiac damage.

Distinguishing Wet Beriberi from Dry Beriberi

Beriberi can be categorized based on its primary system involvement. The distinction is crucial for diagnosis and proper treatment, although some patients may present with overlapping symptoms.


Feature	Wet Beriberi (Cardiovascular)	Dry Beriberi (Neurological)
Primary System	Heart and circulatory system	Peripheral nervous system
Key Symptoms	Shortness of breath, rapid heart rate, lower leg swelling (edema), dilated cardiomyopathy, high-output heart failure	Peripheral neuropathy, numbness, tingling, muscle weakness, partial paralysis
Advanced Stages	Cardiogenic shock, pulmonary congestion, death	Wernicke's encephalopathy, Korsakoff syndrome (memory loss)
Time to Develop	Can develop rapidly (Shoshin) or chronically	Typically develops over a longer period

Identifying and Treating Thiamine Deficiency

Thiamine deficiency is often overlooked, especially in developed countries where it is less common. However, certain populations are at higher risk.

Risk Factors: Chronic alcoholism significantly increases risk due to poor dietary intake and impaired thiamine absorption and metabolism. Other risk factors include bariatric surgery, chronic diuretic use (particularly loop diuretics like furosemide), chronic illness, persistent vomiting (hyperemesis gravidarum), and malnutrition.
Diagnosis: Diagnosis often relies on a high index of suspicion, especially in at-risk individuals with unexplained heart failure. Blood or urine tests for thiamine levels or erythrocyte transketolase activity can confirm the deficiency, although a swift and dramatic response to thiamine supplementation is often a strong indicator.
Treatment: Treatment involves immediate thiamine supplementation. For severe cases, intravenous (IV) thiamine is administered, followed by oral supplements. Supportive care for heart function may also be necessary. With early and adequate treatment, cardiac symptoms can resolve remarkably quickly.

Food sources rich in thiamine include:

Pork
Legumes (black beans, lentils)
Whole grains and fortified cereals
Nuts and seeds (sunflower seeds)
Fish and seafood (trout, mussels)

Conclusion: The Importance of Early Intervention

Thiamine deficiency represents a significant, yet often overlooked, cause of severe cardiac dysfunction, from high-output heart failure to fatal cardiogenic shock. The condition, known as wet beriberi, fundamentally impairs the heart's energy metabolism, leading to impaired contractility and vasodilation. While most prevalent in certain high-risk groups like those with chronic alcoholism, it can affect individuals with chronic illness, malabsorption, or poor diets. Early diagnosis and prompt thiamine supplementation are critical for reversing the life-threatening cardiac effects, with many patients showing dramatic and rapid improvement. Awareness of this nutritional link to heart health is vital for preventing potentially devastating and easily treatable outcomes.

For more detailed information on thiamine's role in health, you can consult the National Institutes of Health (NIH) Office of Dietary Supplements.

Frequently Asked Questions

The main cardiovascular symptom of severe thiamine deficiency is 'wet beriberi,' a form of heart failure. It is characterized by shortness of breath, rapid heart rate, and swelling (edema), which can be fatal if untreated.

Thiamine deficiency impairs the heart's energy production by disrupting key metabolic pathways. This chronic energy deficit overworks the heart muscle, leading to dilation and weakened contractions, eventually causing heart failure.

Yes, cardiac beriberi can present with symptoms similar to other forms of dilated cardiomyopathy. Diagnosis requires a high index of suspicion, a history of poor nutrition, and observing a therapeutic response to thiamine.

Individuals with chronic alcoholism, those who have had bariatric surgery, people taking certain diuretics for long periods, and those with poor nutritional intake are at the highest risk.

Treatment involves immediate thiamine supplementation. In severe cases, intravenous (IV) thiamine is given, followed by oral supplements. Supportive care may be needed to manage heart failure symptoms during recovery.

If diagnosed and treated early, the cardiac damage caused by thiamine deficiency is often reversible, with symptoms improving rapidly. However, if left untreated for too long, some damage may become permanent.

To prevent deficiency, consume a balanced diet rich in thiamine from sources like pork, whole grains, fortified cereals, legumes, and nuts. Limiting consumption of polished white rice and processed foods can also help.