How long does a MRE last?

ok i was in my pantry looking for food cause im hungry. and a few minutes ago i found a bag full of MRE meals and i picked one up opened it and found cappuchino mix and resse's pieces and some pasta stuff i think we got it from huricane ike or katrina whichever was the most recent. are they still good to eat i would think since they are made for the military they would last years and years but i want to make sure first