The oyster is admired for being easy to cultivate and having exceptional taste for culinary creations. They can be found growing in forests on dead wood and plants throughout much of the world. The possible health benefits of oyster mushrooms have been extensively studied, especially during the past three decades. This is because they have been shown to express antibiotic, antiviral, antibacterial, antitumor and anticancer properties at least in vitro (test tube) environments (1). It's important to note however that these are only suspected as being possible benefits and as of today are unproven, as more research is needed. In fact, some research has shown contradictory results.The measurement of oyster's antioxidants is low, as is the case with almost all mushrooms. The reason proponents consume mushrooms is rarely for the antioxidant content and instead, for unique phytonutients they contain which are not found in other foods.
ORAC Source
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010