Are button mushrooms the same as white mushrooms? Yes. Whatever you want to call them, one of the most popular questions which has surfaced about them in recent years is regarding cancer. Are white button mushrooms carcinogenic?
When and where this health scare started, we have not been able to pinpoint. Though in a 2013 edition of Prevention Magazine, Dr. Weil was quoted as saying he never eats raw mushrooms because they have tough cell walls which are difficult to digest. He also stated that they contain small amounts of toxins (without naming them) and some of them are considered carcinogens. He claimed the heat from cooking "thoroughly" destroyed these carcinogens.
While he didn't name the compounds, we assume the one at the forefront of his mind was agaratine. Two studies from the 90's found the substance to be toxic and have a carcinogenic effect on rodents (1). Though other studies have had contradictory results, where rats fed a raw mushroom diet did not get cancer (2). It is highly unlikely that occasionally consuming raw white mushrooms would be dangerous or harmful, though given that at least some research suggests mushrooms cause cancer and are toxic, cooking (whether by baking, frying, or boiling) would not be bad advice to follow, since the heat does destroy agaratine.
As far as the antioxidants found in raw button mushrooms, it's a relatively low amount. More than 90% of the vegetables and fruits in our database achieve higher ORAC values, including many which are cooked, baked, and grilled. Though the low amount of antioxidants is not specific to white button mushrooms, as the highest scoring commonly consumed mushroom, portabella, only scored 968 and that was in the raw form.
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