Selenium
In brief
Section titled “In brief”- Selenium is essential but the requirement is small (~70 mcg/day)
- Diet usually provides enough selenium
- Important for thyroid (T4→T3 conversion) and immune system
- Supplement only with deficiency, thyroid problems, or reduced absorption
- Too much selenium can be harmful
What is selenium?
Section titled “What is selenium?”Selenium is an essential trace element needed for selenoproteins. These proteins:
- Protect against oxidative stress
- Support thyroid function
- Play a role in the immune system
Some tissues, such as brain and thyroid, actively retain selenium because of its importance for their function.
Why is selenium important?
Section titled “Why is selenium important?”| Function | Explanation |
|---|---|
| Neutralization of free radicals | Protects cells against oxidative damage |
| Mitochondrial support | Essential for energy production |
| Conversion of T4 to T3 | Needed for active thyroid hormone |
| Immune regulation | Supports inflammatory processes |
Daily requirement
Section titled “Daily requirement”The average requirement is around 70 micrograms per day.
A balanced diet with meat, fish, eggs, and dairy usually provides enough selenium.
Food sources
Section titled “Food sources”| Source | Note |
|---|---|
| Fish, shellfish, and crustaceans | Good source |
| Meat and organ meat | Rich in selenium |
| Eggs | Reliable source |
| Dairy | Moderate source |
| Brazil nuts | Very high but variable amount |
Selenium and the thyroid
Section titled “Selenium and the thyroid”Selenium plays a crucial role in thyroid function:
- Protects the thyroid against oxidative stress
- Needed for conversion of T4 (inactive) to T3 (active)
- Low status can increase autoimmune activity
Supplementation can improve markers but is not a standard treatment. Temporary supplementation may be considered when selenium levels are low.
Graves’ disease and eye symptoms
Section titled “Graves’ disease and eye symptoms”In Graves’ disease, inflammation behind the eye can lead to orbitopathy (eye symptoms).
- Adequate selenium status is protective
- Temporary supplementation (100-200 mcg/day) can reduce the risk of progression of mild eye symptoms
- Can improve eye function
Reduced absorption
Section titled “Reduced absorption”Selenium absorption may be reduced with:
- Smaller food portions
- Low protein intake
- Repeated diarrhea
- Limited animal-based foods
- Changed digestion or absorption
In these situations, periodic monitoring is useful.
After gastric reduction surgery
Section titled “After gastric reduction surgery”After bariatric surgery, selenium absorption may decrease due to:
- Smaller portions
- Reduced digestion
- Variable tolerance for animal-based foods
- Dumping symptoms
- Irregular supplement intake
Consequences of deficiency:
- Fatigue
- Lower resistance
- Reduced thyroid function
When to supplement?
Section titled “When to supplement?”Supplementation is useful with:
- Measured deficiency in blood
- Active thyroid inflammation (thyroiditis)
- Risk of progression of mild eye symptoms (Graves’)
- Prolonged reduced absorption or repeated diarrhea
Dosage
Section titled “Dosage”| Situation | Dosage | Duration |
|---|---|---|
| Mild deficiency | 50-100 mcg/day | 3-6 months |
| Thyroid/eye symptoms | Up to 200 mcg/day | 3-6 months |
Caution
Section titled “Caution”Excessive intake can lead to:
- Hair loss
- Nail abnormalities
- Gastrointestinal complaints
- Fatigue
- Irritability
- Neuropathy
Summary
Section titled “Summary”| Aspect | Recommendation |
|---|---|
| Requirement | ~70 mcg/day |
| Diet | Fish, meat, eggs, dairy |
| Supplementation | Only with deficiency or indication |
| Dosage | 50-200 mcg/day, 3-6 months |
| Monitoring | Monitor blood levels |
Veelgestelde vragen
What is selenium and why is it important?
Selenium is an essential trace element needed for selenoproteins. These proteins protect against oxidative stress, support thyroid function (conversion of T4 to T3), and play a role in the immune system.
How much selenium do I need per day?
The average requirement is around 70 micrograms per day. A balanced diet with meat, fish, eggs, and dairy usually provides enough selenium.
When should I supplement selenium?
Supplementation is useful with a measured deficiency, active thyroid inflammation, risk of progression of mild eye symptoms (Graves'), or prolonged reduced absorption. Typical dosage is 50-100 mcg per day, sometimes up to 200 mcg, for 3-6 months.
Can I get too much selenium?
Yes, excessive intake can lead to hair loss, nail abnormalities, gastrointestinal complaints, fatigue, irritability, and neuropathy. High doses without indication are not recommended.
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