The adult daily supplement range is 100-200 mcg. Most people are able to get adequate amounts of selenium in their diet. Very small quantities are required for good health. Selenium is found in soil and the content in food is directly proportional to the soil of where the food is raised. Meats, grains, chicken and dairy products are good dietary sources of selenium.
Selenium can be toxic in very high doses.
Symptoms of toxicity can be hair loss, nail problems, tooth decay, swelling of fingers, metallic taste in the mouth, and garlicky breath. Do not take selenium supplements if you are allergic to preparations containing selenium. You should always advise your physician of all over the counter medications you are taking. This includes all vitamins, minerals, supplements and herbs. Chemotherapeutic agents may increase the need for selenium.