It's okay to eat a nut that's gone bad, but it's not pleasant. According to Mother Nature Network, once the unsaturated oils in the nut have oxidized due to exposure to heat, air or light, they become inedible. Unopened almonds at room temperature can usually be good for nine to 12 months after their best-by date. Cashews don't have as long as a shelf life as almonds do, but an unopened package of cashews should last six to nine months after the best-by date has passed.
