I understand that Mountain House, probably the most popular brands, gives a thirty year life for most, if not all, of their products. I believe this is a "best by" date, which means that taste, texture are not noticeably degraded.

Most items can be safety consumed well beyond their best by date. its just that the taste might be a bit off.

Personally, I have consumed a Tanka Bar that was nine years past its date. To me, it was just fine, but take that with a grain of salt, because some have said that my taste buds were shot off in the war.

With canned goods, I would be concerned about leakage or bulging - ditch those pronto...