Selenium is a mineral that’s essential to the body in both pets and people in very small amounts but it can be toxic and even fatal in large dosages. Exceeding 400 micrograms of selenium per day can lead to selenosis, that is poisoning due to excessive intake of selenium.
Selenium is found in varying quantities within agricultural soils throughout the world. So your food will have more or less selenium depending on where it was grown. Regardless, Brazil nuts, fish, and poultry are among the foods richest in selenium. As to dietary requirements and safe limites, the highest tolerable level of selenium is 400mcg daily intake. Consuming 800mcg of selenium can potentially cause toxicity.
Symptoms of Selenium Poisoning: These can include muscle cramps, nausea, vomiting, diarrhea, hair loss, joint pain, fatigue, loss of fingernails, blistering skin, and neurological damage.