Selenium Benefits: 7 Science-Based Reasons Why Your Body Needs This Essential Mineral

Selenium is a trace mineral that plays a crucial role in maintaining optimal health, yet many people don’t know much about it. This powerful nutrient supports everything from your immune system to thyroid function, making it essential for overall wellness.

As an essential mineral, selenium must be obtained through your diet since your body cannot produce it. While only small amounts are needed, selenium is involved in numerous critical bodily processes that impact your daily health and long-term wellbeing.

This comprehensive guide explores seven science-backed benefits of selenium and explains why ensuring adequate intake of this mineral should be a priority for your health.

What Is Selenium and Why Does Your Body Need It?

Selenium is a trace mineral found naturally in soil, water, and certain foods. Your body requires it in small quantities to function properly, but its impact on health is remarkably significant.

This mineral is incorporated into proteins to create selenoproteins, which are essential enzymes that help your body perform vital functions. These selenoproteins act as powerful antioxidants and play key roles in reproduction, DNA production, metabolism regulation, and protection against infection and cellular damage.

The recommended daily allowance for selenium is 55 micrograms (mcg) for adults, with slightly higher needs during pregnancy and lactation. Understanding what selenium does for your body can help you appreciate why maintaining adequate levels is so important.

1. Provides Powerful Antioxidant Protection

One of the most significant benefits of selenium is its role as a potent antioxidant. Selenium helps form selenoproteins that function as antioxidant enzymes, protecting your cells from damage caused by free radicals.

Free radicals are unstable molecules produced naturally during metabolism and in response to environmental stressors like pollution, UV radiation, and cigarette smoke. When free radicals accumulate in excess, they create oxidative stress, which damages cellular structures including DNA, proteins, and cell membranes.

Oxidative stress is implicated in the development of numerous chronic diseases, including cardiovascular disease, cancer, diabetes, and neurodegenerative conditions. It also accelerates aging processes throughout the body.

By neutralizing free radicals before they can cause harm, selenium helps maintain cellular integrity and reduces the risk of oxidative damage. This protective effect extends throughout your entire body, supporting the health of every organ system.

2. Supports Cancer Prevention and Treatment

Research suggests that adequate selenium levels may help reduce the risk of certain types of cancer. The mineral’s anti-cancer properties stem from multiple mechanisms, including reducing DNA damage, decreasing oxidative stress, enhancing immune function, and triggering the destruction of abnormal cells.

Large-scale studies have found associations between higher selenium levels and reduced risk of several cancer types. A comprehensive review analyzing data from over 350,000 participants found that elevated blood selenium levels were linked to lower rates of breast, lung, colon, and prostate cancers.

Importantly, these protective effects were most pronounced when selenium came from food sources rather than supplements. This highlights the importance of obtaining selenium through a balanced diet rich in selenium-containing foods.

For individuals undergoing cancer treatment, selenium may offer additional benefits. Some research indicates that selenium supplementation can help reduce side effects of radiation therapy, potentially improving quality of life during treatment. However, anyone considering selenium supplements during cancer treatment should consult with their healthcare team first.

3. Promotes Heart Health and Reduces Cardiovascular Disease Risk

Selenium plays an important role in cardiovascular health, and low selenium levels have been associated with increased heart disease risk. Multiple mechanisms explain how selenium protects your heart and blood vessels.

Research shows that higher selenium levels in the blood correlate with better cardiovascular outcomes. One analysis of observational studies found that a 50% increase in blood selenium concentration was associated with a 24% reduction in heart disease risk.

Selenium helps protect heart health by reducing inflammation throughout the cardiovascular system. Chronic inflammation damages blood vessel walls and contributes to atherosclerosis—the buildup of fatty plaques in arteries that can lead to heart attacks and strokes.

Studies demonstrate that selenium supplementation can decrease levels of C-reactive protein (CRP), a key marker of inflammation in the body. Selenium also boosts production of glutathione peroxidase, a crucial antioxidant enzyme that protects cells from oxidative damage.

By minimizing both oxidative stress and inflammation, selenium helps maintain healthy blood vessels and reduces the risk of cardiovascular events. Including selenium-rich foods in your diet is a practical strategy for supporting long-term heart health.

4. Essential for Optimal Thyroid Function

Among all organs in your body, the thyroid gland contains the highest concentration of selenium. This mineral is absolutely critical for thyroid health and hormone production.

Your thyroid gland produces hormones that regulate metabolism, energy production, growth, development, and body temperature. Selenium is required for the production and metabolism of these thyroid hormones, making it indispensable for proper thyroid function.

Additionally, selenium protects thyroid tissue from oxidative damage that can occur during hormone synthesis. The antioxidant selenoproteins produced in the thyroid help neutralize harmful byproducts of hormone production.

Selenium deficiency has been linked to various thyroid disorders, including Hashimoto’s thyroiditis—an autoimmune condition where the immune system attacks the thyroid gland. Research indicates that low selenium levels may increase the risk of autoimmune thyroid disease and hypothyroidism.

Some studies suggest that selenium supplementation may benefit individuals with Hashimoto’s disease by reducing thyroid antibodies and improving mood and wellbeing. However, if you have thyroid concerns, work with your healthcare provider to determine the appropriate approach for your situation rather than self-supplementing.

5. Strengthens Immune System Function

A healthy immune system depends on adequate selenium levels. This mineral influences both innate and adaptive immunity, helping your body defend against bacteria, viruses, and other pathogens.

Selenium supports immune health through several mechanisms. It enhances the activity of natural killer cells and other immune cells, improves antibody production, and reduces inflammation that can impair immune responses.

Research shows that selenium deficiency can compromise immune function, leading to slower and less effective immune responses. Conversely, adequate selenium levels are associated with enhanced immunity and better outcomes during infections.

Studies have found that selenium supplementation may benefit individuals with certain infections. Research on people with HIV has shown that selenium deficiency is associated with disease progression and increased mortality, while supplementation may reduce hospitalizations and improve symptoms.

Selenium may also support immune function in people with influenza, tuberculosis, and hepatitis C. During cold and flu season, maintaining adequate selenium intake through diet may help your immune system respond more effectively to viral challenges.

6. May Protect Against Cognitive Decline

Emerging research suggests that selenium may help preserve cognitive function and protect against age-related mental decline. Oxidative stress in the brain is believed to contribute to neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, and multiple sclerosis.

Studies have found that individuals with Alzheimer’s disease often have lower blood selenium levels compared to healthy individuals. This observation has led researchers to investigate whether increasing selenium intake might benefit cognitive health.

Some research indicates that antioxidants, including selenium, may improve memory and cognitive function in people experiencing cognitive decline. One small study found that consuming just one selenium-rich Brazil nut daily improved verbal fluency and other mental functions in people with mild cognitive impairment.

Dietary patterns rich in selenium-containing foods, such as the Mediterranean diet, have been associated with reduced risk of Alzheimer’s disease and better cognitive aging. This diet emphasizes seafood, nuts, and other selenium-rich foods alongside plenty of vegetables, fruits, and healthy fats.

While more research is needed to fully understand selenium’s role in brain health, ensuring adequate intake through diet appears to be a sensible strategy for supporting cognitive function throughout life.

7. May Help Manage Asthma Symptoms

Asthma is a chronic respiratory condition characterized by airway inflammation and narrowing, leading to symptoms like wheezing, shortness of breath, and coughing. Research suggests selenium may offer benefits for people with asthma.

Studies have found that individuals with asthma tend to have lower blood selenium levels compared to those without the condition. Furthermore, asthma patients with higher selenium levels often demonstrate better lung function.

Selenium’s anti-inflammatory properties may help reduce airway inflammation associated with asthma. Some research indicates that selenium supplementation might reduce asthma symptoms and decrease the need for certain medications used to control the condition.

However, research findings in this area are mixed, and more studies are needed to establish clear recommendations. If you have asthma and are considering selenium supplementation, discuss this with your healthcare provider rather than self-treating.

Selenium Benefits for Women

While selenium is important for everyone, women may experience some specific benefits from adequate selenium intake. Selenium supports reproductive health, and adequate levels are particularly important during pregnancy and breastfeeding.

Research suggests that selenium may play a role in fertility and pregnancy outcomes. The mineral’s antioxidant properties help protect reproductive cells from oxidative damage, which can affect fertility.

Selenium requirements increase slightly during pregnancy to support fetal development and maternal health. Adequate selenium during pregnancy supports healthy thyroid function in both mother and baby, which is crucial for proper fetal brain development.

Some research also suggests that selenium may help reduce the risk of preeclampsia, a serious pregnancy complication characterized by high blood pressure. However, women should obtain selenium through a balanced diet rather than high-dose supplements unless specifically recommended by their healthcare provider.

Additionally, selenium’s role in immune function and thyroid health is particularly relevant for women, who are more likely than men to develop thyroid disorders and autoimmune conditions.

Top Food Sources of Selenium

Fortunately, many delicious and nutritious foods contain significant amounts of selenium. The best dietary sources include:

Seafood and Fish:

• Oysters – 238% of daily value (DV) per 3-ounce serving
• Yellowfin tuna – 167% DV per 3-ounce serving
• Halibut – 171% DV per 6-ounce serving
• Sardines – 46% DV per 4 sardines
• Shrimp – provides substantial selenium

Nuts and Seeds:

• Brazil nuts – 174% DV in just one nut (the richest food source)
• Sunflower seeds – 27% DV per ounce
• Cashews and other nuts contain moderate amounts

Meat and Poultry:

• Chicken breast – 12% DV per 4 slices
• Turkey provides good amounts
• Beef and pork contain moderate selenium

Eggs and Dairy:

• Eggs – 56% DV in 2 large eggs
• Cottage cheese and other dairy products provide selenium

Plant-Based Sources:

• Shiitake mushrooms – 10% DV per cup
• Brown rice and other whole grains
• Beans and lentils

It’s important to note that selenium content in plant-based foods varies considerably depending on the selenium concentration in the soil where they were grown. This means the same food grown in different regions may contain very different amounts of selenium.

For this reason, eating a varied diet with multiple sources of selenium is the best approach to ensuring adequate intake. Relying on a single food source may not provide consistent selenium levels.

How Much Selenium Do You Need?

The recommended dietary allowance (RDA) for selenium varies by age and life stage:

• Adults (19+ years): 55 mcg per day
• Pregnant women: 60 mcg per day
• Breastfeeding women: 70 mcg per day
• Children (4-8 years): 30 mcg per day
• Children (9-13 years): 40 mcg per day
• Adolescents (14-18 years): 55 mcg per day

Most people can easily meet these requirements through a balanced diet that includes selenium-rich foods. In fact, many Americans consume more than the RDA through diet alone.

Understanding Selenium Deficiency

True selenium deficiency is relatively rare in the United States and other developed countries, but it can occur in certain circumstances. People at higher risk of deficiency include:

• Individuals living in regions with selenium-poor soil
• People with digestive disorders that impair nutrient absorption (Crohn’s disease, celiac disease)
• Those undergoing dialysis for kidney disease
• People with HIV
• Individuals following very restrictive diets

Symptoms of selenium deficiency may include fatigue, brain fog, weakened immunity, hair loss, and reproductive issues. Severe deficiency can lead to Keshan disease (a heart condition) and Kashin-Beck disease (a joint disorder), though these are rare in developed nations.

If you suspect selenium deficiency, consult with a healthcare provider who can order blood tests to assess your selenium status.

Can You Get Too Much Selenium?

While selenium is essential for health, it’s possible to consume too much. Selenium toxicity, called selenosis, can occur when intake exceeds safe levels over time.

The tolerable upper intake level for selenium is 400 mcg per day for adults. Regularly exceeding this amount can lead to toxic effects. Symptoms of selenium toxicity include:

• Hair loss and brittle nails
• Nausea and vomiting
• Skin rashes and lesions
• Garlic breath odor
• Fatigue and irritability
• Nervous system abnormalities
• Digestive issues

Severe selenium toxicity can cause serious complications including kidney failure, heart problems, and neurological damage.

Toxicity is most likely to occur from taking high-dose supplements rather than from eating selenium-rich foods. However, it’s worth noting that Brazil nuts contain extremely high amounts of selenium—a single nut can provide well over 100% of the daily value. Eating large quantities of Brazil nuts regularly could potentially lead to excessive intake.

For most people, limiting Brazil nut consumption to one to three nuts per day and avoiding high-dose selenium supplements will prevent toxicity while ensuring adequate intake.

Should You Take Selenium Supplements?

For most people, selenium supplements are unnecessary. A balanced diet that includes a variety of selenium-containing foods typically provides adequate amounts of this mineral.

Selenium supplements might be appropriate in certain situations, such as:

• Confirmed selenium deficiency diagnosed by a healthcare provider
• Certain medical conditions that impair selenium absorption
• Living in regions with severely selenium-depleted soil
• Following very restrictive diets that limit selenium-rich foods

If you’re considering selenium supplementation, consult with a healthcare provider first. They can assess whether supplementation is appropriate for your situation and recommend an appropriate dosage.

It’s important to remember that research shows selenium obtained from food sources provides more consistent benefits than supplements, particularly regarding cancer prevention. Food sources also carry virtually no risk of toxicity when consumed as part of a balanced diet.

Maximizing Selenium Absorption

To get the most benefit from selenium in your diet, consider these tips:

Eat a variety of sources: Since selenium content varies based on growing conditions, consuming multiple selenium-rich foods helps ensure adequate intake.

Include protein-rich foods: Many excellent selenium sources are also high-quality protein foods like fish, poultry, and eggs, which provide additional nutritional benefits.

Consider cooking methods: Selenium is relatively stable during cooking, but some may be lost in cooking water. Using cooking methods that don’t require water, or consuming the cooking liquid, can help preserve selenium content.

Balance with other nutrients: Selenium works synergistically with other nutrients, particularly vitamin E and other antioxidants. A diet rich in diverse whole foods provides the nutrient combinations your body needs.

The Bottom Line: What Does Selenium Do for Your Body?

Selenium is a mighty mineral with wide-ranging benefits throughout your body. From acting as a powerful antioxidant to supporting thyroid function, immune health, and cognitive function, this essential nutrient plays critical roles in maintaining optimal health.

The benefits of selenium include:

• Protecting cells from oxidative damage
• Potentially reducing cancer risk
• Supporting cardiovascular health
• Ensuring proper thyroid function
• Strengthening immune responses
• Protecting against cognitive decline
• Possibly helping manage asthma symptoms

For most people, obtaining selenium through a varied diet rich in seafood, nuts (especially Brazil nuts in moderation), eggs, poultry, and whole grains is the best approach. This provides adequate selenium while minimizing any risk of excessive intake.

By understanding what selenium does for your body and ensuring you get enough through your diet, you’re taking an important step toward supporting your long-term health and wellbeing. Whether you’re concerned about heart health, immune function, or thyroid wellness, selenium is a mineral worth paying attention to in your nutrition plan.

Sources:

• National Institutes of Health Office of Dietary Supplements – Selenium
• PubMed Central – Oxidative Stress and Disease
• PubMed Central – Selenium and Cancer Prevention
• PubMed Central – Selenium and Thyroid Health
• PubMed Central – Selenium and Immune Function
• USDA FoodData Central
• National Heart, Lung, and Blood Institute