From the Guidelines
Excessive selenium intake can lead to serious health problems, with symptoms appearing at chronic intakes above 400 micrograms daily, and individuals should not exceed the Tolerable Upper Intake Level of 400 micrograms per day from all sources combined, as stated in the study by 1. The risks associated with high selenium intake include selenium toxicity (selenosis), which can cause a range of symptoms, from mild to severe, including:
- Garlic breath odor
- Metallic taste
- Hair and nail brittleness and loss
- Gastrointestinal disturbances
- Skin rashes
- Fatigue
- Irritability
- Nervous system abnormalities In severe cases, selenosis can lead to cirrhosis, pulmonary edema, and even death, as noted in the study by 1. Management of selenium toxicity primarily involves discontinuing selenium supplementation and avoiding high-selenium foods like Brazil nuts, certain seafood, and organ meats. Treatment is largely supportive, focusing on symptom management as there is no specific antidote, and intravenous hydration may be necessary in severe cases. Prevention is key, and individuals should be aware of the risks of excessive selenium intake, especially if they live in selenium-rich soil areas or have conditions affecting selenium metabolism, as highlighted in the study by 1. Recovery from mild to moderate selenosis typically occurs within weeks to months after removing excess selenium sources, though severe cases may cause permanent damage. It is essential to note that the concern comes from recent awareness that selenium overexposure is positively associated with type 2 diabetes and high-grade prostate cancer, as stated in the study by 1. Therefore, it is crucial to prioritize prevention and be mindful of selenium intake to avoid potential health problems.
From the Research
Risks of High Selenium Intake
- High selenium intake can lead to selenosis, a condition characterized by symptoms such as alopecia, dystrophic fingernail changes, GI symptoms, and memory difficulties 2
- The risk of selenosis is increased when selenium is ingested in large amounts, with a mean estimated cumulative dose of 1.3 gram over a mean period of 37.5 days 2
- Selenium toxicity can manifest within 1 week from the start of ingestion, with initial whole blood selenium concentrations ranging from 150 to 732 mcg/L 2
- Urinary selenium concentrations can also be elevated, ranging from 41 to 220 mcg/g Creatinine, indicating high selenium intake 2
Management of Excessive Selenium Intake
- Supportive care for symptoms is often sufficient, and hospitalization is not usually required 2
- It is essential to monitor selenium levels and adjust intake accordingly to prevent toxicity 3, 4
- The chemical form of selenium exposure, route of exposure, and co-exposures to toxic elements such as mercury can influence the risk of selenosis 3
Factors Influencing Selenium Toxicity
- The narrow range between dietary deficiency and toxic levels of selenium makes it crucial to optimize population selenium intake 5, 6
- Individual biological variation, nutritional status, and general state of health can affect the maximum tolerable level of selenium 4
- The biological activity of selenium, mainly performed through selenoproteins, can have epigenetic effects and influence human diseases 6