Selenium was found to be a harmful substance at the beginning,it is poisonous if human takes too much, leading to loss of hair, fingernail, etc, especially too much of inorganic selenium such as sodium selenite, sodium selenate. Now scientists found it is a must trace element for human health, what are the best sources of selenium element is now the top topic and research direction.
There is a place in China, where people suffered hairloss, fingernail loss in 1960’s, the researchers found the corn grown there and the smoked pork there contained high amount of selenium, polluted by selenium-enriched coal, and caused the local people sick. Then,some plants there were found to contain more selenium than those grown in other places, especially a herb was found to be rich with selenium, that’s Cardamine circaeoides Hook. f. et Thoms.
Some plants like the Astragalus, Cruciferous plants have the property of accumulating selenium from the soil, the accumulating ability or absorption ability varies very much, the cruciferous plants the strongest, then the leguminous plants. Among the grains, the wheat is the strongest.In china, if a product is named organic selenium-enriched product, it means it contains at least 15micrograms of it per kilos for solid products, such as organic selenium-enriched green tea, rice, for liquid products, the limit is 7.5micrograms minimum. The wild Cardamine circaeoides grown in the selenium-rich soil contains as high as 816micrograms selenium, that’s the highest one ever found in China in all kinds of plants.
The selenium in a plant varies also much in its different parts, in grains the seeds contain most, in vegetables the seeds and pods contain most. The organic or inorganic selenium in the soil is absorbed into the plants and become mostly the selenomethionine after Biochemical mechanism,there are also selenoprotein, se-polysaccharides; while in human and animals, the selenium is changed into selenocystine, it is the 21st amino acid.
Selenomethionine and selenocystine can also be available by chemicals, such synthetic organic selenium has high purity, and shall be stored in cool conditions. The biochemical selenium sources need not to be stored in cool, they are more stable.
The maximum dosage is 743-850micrograms per day, the suggest dosage in China is 50 -250micrograms per day.
Selenium-enriched yeast, is a typical product of artificial transformation of inorganic selenium to organic selenium, the selenium can reach 2000ppm to 3000ppm, more than 90% is in form of selenomethionine.
Now cabbage,Cardamine circaeoides,vine tea,Cyclocarya paliurus,and other vegetables and edible plants are grown to be organic selenium sources, usually the dry plant powder contains more than 300mg selenium per kilo, in which 90% more is organic selenium.
