Survivalists and economic doomsayers will be glad to know that you can pretty much survive on potatoes and milk. The only real lack, according to this analysis, can be covered by — c’mon now, guess — yeah. Oatmeal. This is a fine example of the good news being the bad news, which grants this information an immediate place in the halls of Fact without further review.
(Please note that the source site, Straight Dope, is open to any question, meaning you may find some links distasteful. I concurr with the second reader in the pigeon controversy.)