Selenium was identified as a toxin before trace amounts of selenium were recognized to be essential. Selenocysteine is a form of selenium necessary for health, for proteins and in other roles. Some plants, such as Astragalus (Astragalus bisulcatus) accumulate large amounts of selenium that can cause toxicity in animals, which causes pain in horses and other animals. (It is believed to have delayed the arrival of Custer at Little Big Horn.)
There are important interactions between selenium, arsenic and mercury in the mammalian body. Selenium is important in preventing severe reactions to mercury and arsenic. Arsenic in rats and dogs has been shown to prevent toxicity to high doses of selenium. The interactions between these minerals work best when adequate glutathione is present for detoxification.
Chronic intake of arsenic and mercury are seen with depletion of selenium. Increased amounts of selenium may be beneficial in cases of arsenic poisoning. Selenium is also known to be preventive of a number of cancers. Arsenic is not believed to be carcinogenic, but arsenic may increase the frequency of cancers by causing depletion of selenium, especially in areas of low dietary intake of selenium. Selenium protects marine mammals and seabirds from silver, copper and zinc toxicity.
CONCLUSION: “…selenium not only serves as an essential constituent of the key amino acid, selenocysteine, in many enzymes, but is also an important detoxicant of other metals and metalloid elements.” There is a complex relationship between selenium, arsenic and mercury. Increased risk of cancer seems to be related to depletion of the protective effect of selenium caused by chronic exposure to arsenic or mercury.
NOTE: Read about selenium and mercury in pellagic fish.
ASK YOUR DOCTOR FOR: Hair analysis for heavy metal or mineral testing can give information about your body’s exposure to both toxic and essential metals over a period of time.
To read the author’s abstract of the article click on the link to the author’s title of the article above.
PMID: 17644180.
Summary #220.
