Selenium
Description: A trace mineral.
Properties: Antioxidant effect with vitamin E. Selenium may help allow vitamin E to be more effective. Functions in reproduction and immune function.
Actions: A component of the antioxidant enzyme, glutathione peroxidase. Glutathione peroxidase works with vitamin E in preventing free-radical damage to cell membranes.
Selenium has a sparing effect on vitamin E: less vitamin E is required to maintain cell membrane integrity due to the synergysm with glutathione peroxidase.
Cautions: High intake levels can lead to toxicity. Never give more that 200 µg of selenium per day in large dogs nor more than 100 µg per day to small dogs.