Selenium is an essential mineral which works closely with vitamin E. Toxicity is more of a problem with selenium than most nutrients, and doses over 800 to 1000mcg should be used with caution or under a doctor's supervision only. The National Academy of Sciences' Food and Nutrition Board has stated that a daily intake of between 50 to 300 micrograms of selenium is "safe and adequate". Therapeutic doses often range from 200 to 400mcg daily. Selenium is absorbed fairly easily in the upper portion of the GI tract. Organic and inorganic forms of selenium may have different properties. Organic forms include selenomethionine, selenocysteine, amino acid chelates, yeast, and kelp-bound selenium. Inorganic forms include sodium selenite and sodium selenate. Incrementally increasing doses of sodium selenite are being used for decreasing sensitivity to environmental toxins. Your naturopath should be familiar with this protocol.

Selenium is naturally found in foods high in protein, such as fish, meat, poultry, cereals, seeds and other grains. It can also be found in vegetables like garlic, mushrooms and asparagus. Brazil nuts, especially with their shells on, are very high in selenium. Some experts believe that vegetarians may not be getting enough selenium unless supplemented.

Natural selenium levels in the soil are highly variable throughout the world. In the U.S., the Eastern Coastal Plain and the Pacific Northwest have the lowest selenium levels and people in these regions naturally ingest about 60 to 90mcg per day. This compares to a range of 60 to 200mcg across the U.S. with 125mcg being average.

A study was conducted in the above region. People in this study were given either a placebo or selenium supplements of 200mcg (three times their normal intake) which were made up of selenium enriched yeast, an organic form of selenium as distinguished from most other supplements that are inorganic and may not have the same effect. While the study did not prove what it originally set out to, namely that selenium reduces the risk of skin cancer, it did find that it greatly reduced the risk of many other kinds of cancer. People taking the selenium supplements had 71% fewer prostate cancers, 67% fewer esophageal cancers, 62% fewer colorectal cancers and 46% fewer lung cancers than the people who were taking the placebos.