Which Organ Is Damaged by a Selenium Deficiency?

October 3, 2025 •

4 min read

Millions of people worldwide suffer from insufficient selenium intake, a trace mineral essential for numerous physiological functions. A deficiency can impact multiple organs, but severe, long-term depletion is particularly damaging to the heart, leading to a condition known as Keshan disease.

Quick Summary

Severe selenium deficiency can lead to significant organ damage, most famously affecting the heart and causing cardiomyopathy. It also impacts the thyroid gland, liver, and immune system, among other vital functions. The severity depends on the duration and extent of the deficiency.

Key Points

Heart Damage: Severe selenium deficiency can cause Keshan disease, a congestive cardiomyopathy characterized by an enlarged, weakened heart muscle.
Thyroid Dysfunction: The thyroid gland holds the highest selenium concentration in the body, and its deficiency impairs hormone conversion, potentially leading to hypothyroidism.
Increased Oxidative Stress: Selenium is crucial for antioxidant enzymes like glutathione peroxidase, so a deficiency leads to increased free radical damage to cells in vital organs.
Liver Damage: Low selenium levels are associated with increased oxidative stress in the liver, contributing to advanced liver fibrosis and other chronic liver diseases.
Muscle Weakness: Moderate to severe deficiency can cause myopathy, resulting in muscle weakness, pain, and fatigue, which is often reversible with supplementation.
Compounded Risk: The damage from selenium deficiency is often compounded by other factors, such as viral infections, which can increase virulence in a selenium-compromised host.
Geographic Influence: The risk of deficiency is closely tied to geography, as the selenium content of soil varies by region and affects the mineral content of food grown there.

The Primary Target: The Heart

While selenium is vital for many bodily functions, the heart is the most vulnerable organ in cases of severe deficiency. A lack of selenium can lead to a potentially fatal form of congestive cardiomyopathy known as Keshan disease, named after a region in China where soil selenium levels are extremely low. The condition is characterized by a weakened, enlarged heart muscle and has been found to be exacerbated by viral infections, such as certain strains of Coxsackievirus.

The Mechanism of Heart Damage

Selenium's role in heart health is primarily through selenoproteins, especially glutathione peroxidase (GPx), a powerful antioxidant. In a selenium-deficient state, the activity of these protective enzymes is severely compromised, leading to increased oxidative stress and free radical damage to heart cells.

Oxidative damage to the myocardium (heart muscle).
Inflammation and fibrosis of heart tissue.
Disruption of antioxidant defenses within heart cells.

The Thyroid Gland: A High-Priority Organ

The thyroid gland has the highest concentration of selenium per gram of tissue in the body and is another key organ affected by deficiency. Selenium is integral to the function of iodothyronine deiodinases, enzymes that convert the inactive thyroid hormone (T4) into its active form (T3).

Consequences for the Thyroid

A selenium deficiency disrupts this crucial conversion process, leading to symptoms of hypothyroidism. Chronic deficiency is also linked to a higher risk of autoimmune thyroid diseases like Hashimoto's thyroiditis and Graves' disease.

Impaired thyroid hormone metabolism.
Increased oxidative damage to thyroid cells due to reduced antioxidant protection.
Exacerbation of autoimmune thyroid conditions.

The Liver and Its Role in Selenium Metabolism

The liver plays a central role in selenium metabolism, functioning as a storage organ and producing key selenoproteins, including Selenoprotein P, which transports selenium throughout the body. Research has shown a correlation between low serum selenium levels and the severity of chronic liver diseases, such as fibrosis and cirrhosis.

Liver Damage from Deficiency

Oxidative stress is a recognized mechanism in the progression of liver disease. With compromised antioxidant defenses from selenium deficiency, liver cells become more susceptible to damage.

Increased risk of liver fibrosis and cirrhosis.
Reduced antioxidant protection for liver cells.
Potential contribution to conditions like nonalcoholic fatty liver disease (NAFLD).

Skeletal Muscles and Neurological Function

Moderate selenium deficiency can lead to musculoskeletal problems, manifesting as muscle weakness, myalgia, and fatigue. Severe cases in humans have shown reversible myopathy that responds to selenium supplementation. In infants and young children in certain regions, severe deficiency combined with low iodine can cause Kashin-Beck disease, a deforming osteoarthropathy.

Damage to Muscles and the Brain

Skeletal Muscle: Oxidative damage can impair muscle function and contraction. Selenoprotein N plays a vital role in muscle calcium homeostasis, and its deficiency can lead to severe myopathies.
Brain and Nervous System: Selenium deficiency can lead to neurodegenerative diseases, cognitive decline, mood disturbances, and impaired neurological function. The brain prioritizes selenium during deficiency, highlighting its critical role.

Comparison: Selenium Deficiency vs. Adequacy


Feature	Selenium Deficiency	Selenium Adequacy
Heart	Increased risk of cardiomyopathy (Keshan disease) and heart failure due to oxidative damage.	Strong antioxidant protection; normal heart muscle function.
Thyroid	Impaired hormone conversion (T4 to T3), increased risk of hypothyroidism and autoimmune thyroid diseases.	Efficient hormone metabolism; protects against oxidative damage.
Liver	Reduced antioxidant defense, increased oxidative damage, and higher risk of fibrosis and chronic liver disease.	Supports liver function; potent antioxidant protection against damage.
Muscles	Muscle weakness, pain, and myopathy due to oxidative stress and impaired cell function.	Normal muscle function, supports muscle strength and health.
Immune System	Weakened immune response, higher susceptibility to infections and viral virulence.	Enhanced immune function, stronger defense against pathogens.
Antioxidant Capacity	Compromised antioxidant protection, increased cellular damage from free radicals.	Optimal defense against damaging reactive oxygen species.

The Role of Genetics and Viruses

While severe selenium deficiency is a prerequisite for endemic diseases like Keshan and Kashin-Beck diseases, it is not the sole cause. A selenium deficiency can leave the body vulnerable to additional environmental factors, such as viral infections or other nutritional deficiencies. For example, studies in mice have shown that a benign Coxsackievirus becomes more virulent and causes myocarditis when the host is selenium-deficient. This demonstrates a powerful synergistic effect that can cause significant organ damage where simple deficiency might not.

The Importance of Selenium Status

Regular intake of selenium from dietary sources is crucial for preventing deficiency and protecting various organs. The selenium content in soil varies by region, which directly affects the mineral content of locally grown food. This is why supplementation efforts have been so effective in endemic areas like parts of China. The balance is key, however, as excessive selenium intake can lead to toxicity with its own set of adverse effects.

Conclusion

In conclusion, while a selenium deficiency can affect multiple organs, the heart is the most famously and severely impacted, with the potential to develop fatal cardiomyopathy. The thyroid is also a high-priority organ for selenium, where a deficiency can disrupt hormone metabolism and exacerbate autoimmune conditions. The liver, skeletal muscles, and nervous system are all vulnerable to the increased oxidative stress that results from a lack of this essential trace mineral. Prevention through adequate dietary intake or supplementation is the primary strategy for avoiding the multisystemic damage caused by selenium deficiency.

Frequently Asked Questions

The most serious consequence of severe selenium deficiency is Keshan disease, a form of cardiomyopathy that causes an enlarged, weakened heart and can lead to heart failure and death, particularly in children and women of childbearing age.

The thyroid gland relies on selenium to produce and regulate hormones. A deficiency impairs the conversion of inactive T4 to active T3, and can increase the risk and severity of autoimmune thyroid diseases like Hashimoto's and Graves' disease.

Yes, the liver is essential for selenium metabolism. Low selenium status is linked to higher oxidative stress and liver damage, increasing the risk of fibrosis and chronic liver disease.

Selenium is crucial for a healthy immune response. A deficiency can weaken the immune system, increase susceptibility to infections, and even make some viruses more virulent within the body.

Yes, muscle weakness, fatigue, and pain are common symptoms of moderate to severe selenium deficiency. This myopathy is generally reversible with appropriate supplementation.

In a selenium-deficient state, oxidative stress can cause mutations in normally benign viruses, making them more virulent and damaging to the host, as seen with some Coxsackievirus strains causing Keshan disease.

Ensuring adequate intake through a diet rich in selenium is the primary prevention method. Sources include Brazil nuts, seafood, meat, and grains. In areas with low soil selenium, supplementation may be necessary.