The well-known chemist Berzelius first discovered selenium in 1817. He bestowed the name "selenium" after the Greek moon goddess Selene, patron of conjurers and magicians and also the daughter of Hyperion and Theia. Selenium derives from the sulfur family and chemically resembles the important nutrient sulfur.
Selenium is a trace element that is essential to both animals and humans. Also known as microminerals or micronutrients, trace elements are critical to an organism's survival. These dietary minerals occur in very minute quantities in substances and organisms. Selenium's nutritional requirements in humans and animals call for very minimal measures, which are typically met through a normal diet.
RECOMMENDED DIETARY DOSES OF SELENIUM
The Recommended Daily Allowance of selenium varies based on age and gender, ranging from 50 to 70 *g per day (NRC 1989 ). While selenium exists in many naturally occurring sources, many diets may lack even this small dose of selenium.
The Environmental Protection Agency established a reference dose of 350 *g per day for an adult male of average weight (Poirier, K.A. 1994). The Food and Nutrition Board of the National Academy of Sciences is reviewing the safe upper level of selenium uptake, which is currently estimated to be safe and adequate at 200 *g per day (NRC 1980).
ABSORPTION OF SELENIUM
Absorption of selenium takes place along the entire gastrointestinal tract. With organic forms of selenium, absorption and hepato-pancreatic uptake increase. For example, selenomethinone faces greater absorption than selenite.
Inadequate amounts of selenium in the diet may negatively impact one's health, as demonstrated in various studies.
Insufficient dietary selenium may contribute to:
- Heart disease
- Perhaps even Alzheimer's
Adequate levels of selenium in the diet are partially due to its functional role in the antioxidant enzymes, glutathione peroxidases and its role in controlling the effects of thyroid hormone on fat metabolism.