Golden oyster mushrooms growing on a fallen log in IowaKatie Flenker / AlamyRegularly eating golden oyster mushrooms protected heart health and promoted longevity in mice.Golden oyster mushrooms (Pleurotus citrinopileatus) fungi native to parts of Russia, China and Japan are one of the richest natural sources of an antioxidant called ergothioneine. Studies in humans have shown the compound is associated with a lower risk of heart disease and premature death. These findings rely on observational data, however, so it isnt clear whether ergothioneine is driving the health benefits.