Selenium excess is rare and is caused by consuming too much of the mineral selenium.
Selenium occurs in all tissues. Selenium works with vitamin E as an antioxidant. It helps protect cells against damage by free radicals, which are reactive by-products of normal cell activity. Selenium may help protect against some cancers. Selenium is also necessary for the thyroid gland to function normally.
Taking more than 900 micrograms of a nonprescription selenium supplement each day can have harmful effects. Symptoms of selenium toxicity are mainly gastrointestinal upset, including nausea, vomiting, and diarrhea. Other symptoms include hair loss, abnormal nails, a rash, fatigue, and nerve damage. The breath may smell like garlic.
The diagnosis of selenium excess is based on a history of selenium supplementation and symptoms. Blood or urinary selenium levels can be measured.
Treatment of selenium excess involves reducing selenium consumption.
