Selenium is one of the trace mineral that is essential for human health. A small amount of selenium is needed for various activities in the body. It plays an important role in synthesizing enzymes that are necessary for metabolic activities. This trace mineral is found naturally in soil, water and some foods. Although selenium in trace amount is essential for maintaining normal health, large dose of selenium can produce devastating effects which may sometimes be life-threatening.
The recommended daily dose of selenium is in an adult is 80-200 micrograms (mcg). A dose of more than 800 micrograms (mcg) is known to cause selenium toxicity.Anything more than this can be lethal. Since selenium poisoning does not have any antidote, it is important to recognize signs and symptoms as early as possible to prevent mortality.
Dietary Sources Of Selenium
Most of the human requirements for selenium are met by eating well balanced diet. The natural source of selenium is present in certain foods such as brazil nuts and walnuts, fresh and salt water fish such as tuna, herring etc. Beef, poultry, and grains also contain selenium.
Since selenium is present in soil, it is present in plants and vegetables.Broccoli, mushroom, cabbage, cucumber, celery, onions, garlic, radishes, brewer’s yeast, grains and cereals contain selenium. Besides the natural source, selenium is also available in vitamin and mineral supplements.
How Do You Get Selenium Toxicity?
Selenium is found in soil and water. Some regions in the world have high level of selenium in the soil. Naturally plants grown in such soil have higher level of selenium. The live stocks which feed on such plants are exposed to its toxicity. Therefore people who consume these vegetables, crops and animals are exposed to too much of selenium.
Also excessive supplementation of selenium increases the risk of selenium poisoning. Besides, selenium is also used in certain photographic devices, plastics and paints, anti dandruff shampoos. Exposure to such products in large amount can increase the risk of selenium toxicity.
Signs And Symptoms Of Selenium Toxicity
Selenium is essential for the body, but in high doses than the required normal amount can be harmful for the body. Selenium poisoning can produce several symptoms such as;
- Selenium poisoning can irritate the mucus membrane of respiratory tract. Patient may complain of cough, typical garlic odor while breathing, inflammation in bronchial passage, shallow respiration, fluid in lungs.
- Stomach upsets, vomiting, nausea, diarrhea, metallic taste in mouth, and intestinal cramps are common finding in selenium toxicity.
While the above are some of the short term symptoms that may develop after exposure to too much of selenium, there are certain long term symptoms due to chronic oral exposure to high amount of selenium. Chronic symptoms are also called selenosis.
The major symptoms include hair loss, brittle nails, deformed nails, discoloration of teeth and skin. Selenium poisoning can also damage brain and nerves. Its symptoms include hand tremors, memory lapses, fatigue and mental irritability, numbness in legs, hands, arm and feet.
Treatment Of Selenium Overdose
Selenium poisoning is usually diagnosed clinically by physician. There is no antidote for selenium poisoning. Patient may give history of taking selenium supplement. History of large amount of selenium supplement is suggestive of selenium poisoning from the symptoms and signs. Therefore the first step of treatment is to stop taking mineral supplements containing selenium immediately.
Management of selenium poisoning consists primarily of treating the symptoms. High level of selenium in body naturally gets eliminated over a period of time. During this period patient is advised to eat well balanced diet.