Selenium is a valuable and essential mineral for human nutrition. This trace mineral works with Vitamin E to enhance immunity and create enzymes that protect the body from harmful peroxides. As an antioxidant, selenium has emerged as a critical nutrient for the prevention of many diseases and is essential for people of all ages.
People with low body stores of selenium have a greater chance of developing cancer, heart disease, inflammatory disease, cataracts, and signs of premature aging. Low blood and liver levels of the mineral are also common among persons suffering from chronic liver disease. Even a marginal selenium deficiency can be detrimental, negatively affecting mood, anxiety, and energy levels.
Deficiencies of the mineral in crops and soil have been linked to cancer rates in many locations. Cancer death rates have been shown to be much less in areas where the mineral content of the soil is highest. Selenium has been shown to be protective against esophageal, stomach, colon, and rectal cancers. For women, boosting selenium intake appears to exert a powerful effect against the development of breast cancer. The correct amount to be ingested each day is uncertain, but people who eat a balanced diet of food grown in the western United States probably get enough from food.
Selenium overdose and overexposure
Overdosing on selenium is possible, but unlikely if mineral supplements are not consumed at a rate greater than the dose recommended by the manufacturer. Toxicity may develop over time at doses of 900 mcg per day. Toxicity from dietary sources is very rare. Symptoms may include depression, nervousness, emotional problems, nausea, and vomiting.
Individuals in industrial settings have been reported to suffer toxic symptoms of selenium overdoses, including liver disease and cardiomyopathy. Children raised in selenium-rich areas show a higher incidence of decayed, missing and filled teeth. Selenium is toxic in megadoses and may cause hair loss, loss of nails, fatigue, nausea, vomiting, and sour-milk breath.
Workers at industrial sites that manufacture glass, pesticides, rubber, semi-conductors, copper and film are at increased risk of developing toxic symptoms from inhalation, absorption through the skin and ingestion. These may include bronchial pneumonia, asthma, precipitous drop in blood pressure, red eyes, garlic odor on breath and in urine, headaches, metallic taste, nose and throat irritation, difficulty breathing, vomiting, and weakness.
Source:
http://www.vitaminsplus.com/library/minerals/selenium.asp
Back to CEHS website:
http://www.envtox.ucdavis.edu/CEHS/Index.htm