MUSHROOM Portobello, (agaricus bisporus), button mushrooms are grown in many countries. When white immature, this is called common mushroom or button mushroom. When it is brown it is called a Portobello. It contains ergocalciferol (vitamin D2), sodium, potassium, phosphorus, linoleic acid, antioxidants. It inhibits aromatase, an enzyme that contributes to estrogen production. By eating Agaricus bisporus the risk of developing breast cancer might be lowered.