What is selenosis (selenium toxicity)?

From the Guidelines

Selenosis, or selenium toxicity, is a condition characterized by headache, loss of hair and nails, skin rash, discoloration of teeth, paresthesia, and paralysis in adults, resulting from excessive intake of selenium. Selenium is an essential nutrient that acts mainly in antioxidant defense, and its deficiency can lead to various health issues, including low plasma selenium, erythrocyte macrocytosis, depigmentation, and muscle weakness 1. However, high-dose selenium supplements are not recommended, as there is only a narrow margin between safe and toxic dosages 1.

Key Points

• Selenium plays important roles in thyroid function, antioxidant defense systems, and immune function.
• The recommended daily allowance for adults is typically 55 micrograms per day.
• High-dose selenium supplements can lead to selenosis, characterized by headache, loss of hair and nails, skin rash, discoloration of teeth, paresthesia, and paralysis in adults.
• Selenium status is usually monitored by measuring selenium concentrations in serum or plasma and/or the activity of glutathione peroxidase (GSHPx) in plasma or red blood cells 1.
• Certain groups, such as patients with burns, major trauma, or cardiac surgery, may require higher amounts of selenium, up to 375 mg/day, with monitoring of plasma selenium levels 1.

Recommendations

• The maximum dose of selenium in a supplement should not exceed 200 micrograms per day 1.
• Patients who are depleted due to reduced intake may require twice the normal daily amount, up to 200 mg/day, with monitoring of plasma selenium level 1.
• Parenteral intake of 7 mg/kg/day in preterm infants is recommended to reach selenium status similar to that of term infants 1.

Important Considerations

• Selenium intake should be carefully monitored to avoid toxicity, especially in vulnerable populations such as preterm infants and patients with renal failure 1.
• The decision to provide an increased amount of selenium depends on the objective, risk of not taking any active measures, and availability of the gastrointestinal tract 1.

From the Research

Definition of Selenosis

Selenosis, also known as selenium toxicity, occurs when the body ingests excessive amounts of selenium, leading to harmful effects.

Causes and Effects of Selenosis

• Selenium is an essential trace element necessary for human health, but excessive intake can cause toxicity 2, 3.
• The range between selenium's nutritional and toxic doses is very narrow, making it crucial to control intake within a precise range 2.
• Insufficient daily selenium intake can lead to selenium deficiency, while excessive intake carries the risk of selenium toxicity 2.
• Selenosis can result from consuming high amounts of selenium, which can occur through various means, including supplementation or ingestion of selenium-rich foods 4, 3.

Symptoms and Consequences of Selenosis

• Excessive selenium intake can lead to toxicity, causing harm to the body 3, 5.
• The exact mechanisms underlying selenium toxicity are not fully understood, but it is known that high doses can have pro-oxidant effects 5.
• Studies have shown that doses above the tolerable upper intake level (400 microg) may be associated with adverse effects, and higher doses (up to 800 microg) may be of interest for further study 5.

Importance of Selenium Intake Control

• It is essential to control selenium intake within a relatively precise range to avoid deficiency or toxicity 2, 3.
• Selenium supplementation should be done carefully and cautiously, as slight differences in selenium content can result in excess or deficiency 4.