What are the benefits and recommended dosages of selenium supplements?

Selenium Supplement Benefits and Recommended Dosages

Selenium supplementation is beneficial primarily for preventing deficiency, with recommended dosages of 100 μg/day for routine supplementation in adults, while higher doses should be reserved for specific clinical situations with documented deficiency or increased requirements. 1

Benefits of Selenium Supplementation

Selenium is an essential trace element with important functions in the body, primarily related to its antioxidant properties:

• Antioxidant defense: Selenium is a crucial component of glutathione peroxidase (GSHPx), an enzyme that protects against oxidative tissue damage 1, 2
• Immune function: Selenium deficiency is associated with increased incidence and virulence of viral infections 1
• Thyroid function: Selenium is involved in thyroid hormone metabolism 1

Clinical Benefits in Specific Populations

Certain patient groups may benefit from selenium supplementation:

• Patients with documented deficiency: Those with plasma selenium <0.4 mmol/L (<32 μg/L) should receive supplementation 1
• Burns patients: Benefit from higher doses (375 μg/day) with evidence of more rapid healing and fewer infections 1
• Major trauma and cardiac surgery patients: May benefit from 275 μg/day 1
• Patients on renal replacement therapy: Have increased losses and oxidative stress requiring higher supplementation 1
• Patients on long-term parenteral or enteral nutrition: At high risk for deficiency 1, 3, 4

Recommended Dosages

For Adults:

• Standard supplementation: 100 μg/day for routine supplementation 1
• Deficiency correction:
  • Mild deficiency (plasma selenium <0.75 mmol/L without inflammation): 100 μg/day 1
  • Severe deficiency (plasma selenium <0.4 mmol/L): 100-400 μg/day for at least 7-10 days 1
• Special clinical situations:
  • Burns patients: 375 μg/day 1
  • Major trauma/cardiac surgery: 275 μg/day 1
  • Patients with recent reduced intake: up to 200 μg/day 1

For Children:

• Preterm infants: 7 μg/kg/day parenterally 1
• Term infants and children: 2-3 μg/kg/day up to maximum 100 μg/day 1

Monitoring and Safety Considerations

When to Monitor

• All patients on long-term parenteral nutrition should have plasma selenium and CRP measured initially and every 3-6 months 1
• Patients with renal failure require regular monitoring 1

Toxicity Concerns

• Upper limits for plasma selenium before toxicity symptoms occur range from 6-12 mmol/L 1
• Selenium toxicity (selenosis) can cause:
  • Headache, hair and nail loss, skin rash
  • Discoloration of teeth, paresthesia, paralysis 1
  • Increased risk of type 2 diabetes and high-grade prostate cancer 1

Clinical Approach to Supplementation

1. Assess risk factors for selenium deficiency:

   • Long-term parenteral/enteral nutrition
   • Burns, trauma, or critical illness
   • Renal replacement therapy
   • Gastrointestinal losses (fistulas, short bowel)

2. Measure plasma selenium and CRP (for interpretation) in at-risk patients

3. Determine supplementation need:

   • If plasma selenium <0.4 mmol/L: Immediate supplementation required
   • If plasma selenium <0.75 mmol/L without inflammation: Supplementation recommended

4. Choose route of administration:

   • Oral/enteral route preferred when gastrointestinal tract is available (good absorption)
   • IV route for severe deficiency or when rapid correction is needed

5. Recheck status after 7-10 days of supplementation for severe deficiency

Important Cautions

• Uncontrolled self-medication is not recommended due to selenium's toxic potential 5
• The therapeutic window between beneficial and toxic doses is narrow 2
• High-dose selenium (1000-4000 μg/day) in ICU patients shows no consistent benefit and is advised against 1
• Always interpret plasma selenium levels in conjunction with inflammatory markers (CRP), as inflammation can decrease plasma selenium levels 1