Introduction:
Selenium is needed only in tiny amounts, but a lack of it can have far-reaching effects. Because this mineral plays roles in hormone function, immune strength, and antioxidant protection, a deficiency doesn’t go unnoticed for long.
In this article, we’ll explore what selenium deficiency looks like, who is most at risk, and the signs your body might be sending if your levels are too low.
Why Selenium Deficiency Can Happen
Selenium is mostly obtained through food, but the amount in food depends on the selenium content of the soil in which plants are grown or animals are raised. In some regions—like parts of Europe, China, and New Zealand—soils are naturally low in selenium, increasing the risk of deficiency through no fault of your diet.
In addition to geographic factors, selenium deficiency can also arise due to:
- Digestive conditions that limit absorption
- Restrictive diets (especially those with little variety)
- Long-term tube feeding or kidney dialysis
- Certain genetic mutations affecting selenoprotein function
Common Signs of Selenium Deficiency
Selenium deficiency often develops gradually and can be subtle at first. The symptoms are usually tied to the areas where selenium has the strongest influence: thyroid health, immune function, antioxidant protection, and fertility.
1. Fatigue and Low Energy
Selenium is essential for converting thyroid hormone into its active form. Without it, your metabolism may slow down—leading to unexplained tiredness or sluggishness.
2. Weakened Immune Function
Frequent colds, prolonged infections, or slower recovery can suggest that your immune system isn’t operating at full strength.
3. Thyroid Imbalance
A deficiency may increase the risk of thyroid inflammation and disorders such as Hashimoto’s thyroiditis, especially in individuals with low iodine intake.
4. Cognitive and Mood Changes
Low selenium levels may affect brain chemistry and contribute to symptoms like brain fog, low mood, or poor concentration—especially in older adults.
5. Muscle Weakness or Pain
In severe or prolonged cases, muscle discomfort and weakness may develop, particularly in children.
Serious Selenium Deficiency: Rare but Dangerous
In areas where selenium intake is extremely low, two rare but serious conditions have been documented:
- Keshan disease – A heart disorder that primarily affects children and women of childbearing age, linked to very low selenium status.
- Kashin-Beck disease – A bone and joint disorder that can lead to deformities and stunted growth, also associated with selenium-deficient regions.
Summary Table: Symptoms and Risks of Selenium Deficiency
| System Affected | Possible Signs of Deficiency |
| Energy/metabolism | Fatigue, cold intolerance, slowed metabolism |
| Immune system | Frequent infections, prolonged recovery |
| Thyroid | Enlarged thyroid (goiter), inflammation, hypothyroid symptoms |
| Cognitive health | Brain fog, memory issues, irritability |
| Muscle function | Weakness, discomfort (in severe deficiency) |
| Heart/bone development | Risk of Keshan or Kashin-Beck disease (in endemic regions) |
Conclusion:
Selenium deficiency is more common than it may seem—especially for those living in low-selenium areas or managing chronic health conditions. Even mild insufficiency may subtly interfere with thyroid, immune, or mental health.