Selenium yeast, produced by fermenting Saccharomyces cerevisiae in a selenium-rich media, is a recognized source of organic food-form selenium. Selenium is a fundamental trace element, which is closely related to human health. Selenium can prevent and inhibit tumor, anti-age and maintain the normal functions of cardiovascular system. Selenium yeast is the best source of organic selenium. The absorption and utilization of organic selenium is much higher than the inorganic selenium, and the toxicity of organic selenium is much lower.