Selenium is a powerful trace mineral that plays a vital role in human health. Though needed only in small amounts, selenium contributes to numerous biological functions, including immune defense, antioxidant protection, thyroid hormone metabolism, and even mood regulation. It is naturally found in soil, water, and certain foods.

1. Antioxidant Powerhouse

Selenium is an essential component of glutathione peroxidase, a key antioxidant enzyme that protects cells from oxidative stress and damage.

• Benefit: Helps neutralize free radicals and may reduce risk of chronic diseases such as heart disease, cancer, and cognitive decline.

2. Immune System Support

Selenium enhances the immune response by supporting white blood cell activity and reducing inflammation.

• Tip: Selenium is often included in immune-boosting supplement blends alongside zinc, vitamin C, and quercetin.

3. Thyroid Function

The thyroid contains more selenium per gram of tissue than any other organ. It is essential for the conversion of T4 (inactive thyroid hormone) to T3 (active form).

• Support: May reduce symptoms of Hashimoto's thyroiditis and help maintain stable energy and metabolism.

4. Antiviral Effects

Selenium has shown antiviral properties in both clinical and experimental studies. Deficiency may increase susceptibility to viral infections and worsen outcomes.

• Application: Often used as part of a natural protocol for chronic viral conditions such as EBV or long-term post-viral fatigue.

5. Fertility and Reproductive Health

Selenium supports sperm motility and DNA integrity, and is also important for female reproductive health during pregnancy.

• Note: Adequate selenium levels may help prevent miscarriage and support fetal development.

6. Mood and Brain Health

Low selenium levels have been linked to mood disturbances and cognitive decline.

• Benefit: May support mood balance and reduce anxiety or irritability, especially in individuals with low dietary intake.

7. Skin Health

Selenium supports skin integrity by protecting against oxidative stress, inflammation, and premature aging.

• Benefit: Helps reduce acne, dryness, and signs of aging by supporting cellular repair and elasticity.
• Synergy: Works well with vitamin E, zinc, and omega-3s to support a clear, healthy complexion.
• Topical Use: Some skincare products include selenium for its anti-inflammatory and antioxidant properties.

8. Sun Protection and Eye Health

Selenium may play a role in protecting the skin and eyes from oxidative damage caused by UV rays and environmental stressors.

• Sun Protection: By reducing inflammation and cellular damage, selenium supports the skin’s resilience to sun exposure and may help prevent sunburn-related stress and aging.
• Eye Health: Antioxidant selenium works alongside nutrients like vitamin A and lutein to protect the eyes from age-related degeneration and oxidative stress.

Best Food Sources of Selenium

• Brazil nuts (1–2 nuts may provide over 100% daily value)
• Wild-caught fish (tuna, sardines, salmon)
• Sunflower seeds
• Pasture-raised eggs
• Grass-fed meats and organ meats

Dosage and Safety

The recommended daily allowance (RDA) for selenium is around 55 mcg for adults. However, therapeutic doses up to 200 mcg are commonly used for immune and thyroid support.

• Warning: Excessive selenium (above 400 mcg/day) can lead to toxicity symptoms such as nausea, fatigue, or hair loss.

Experimenting With Selenium

Like many nutrients, selenium affects people differently. Some may feel benefits such as better energy or immune resilience within days, while others may respond better to food-based selenium or synergistic supplements. Track your symptoms and adjust the dose slowly to find what works best for your body.

Conclusion

Selenium is a small but mighty mineral with wide-reaching effects on your health—from boosting antioxidant activity and immune defense to supporting thyroid, skin, eye, and brain function. Whether through food or supplements, keeping your selenium levels optimal may offer lasting health benefits.

Keep reading below to explore how Earth Clinic readers have used selenium to support their health, and share your results if it has helped you too!