Every once in a while some of my energy bars go into hiding, not to emerge until well after their "sell by" dates, sometimes by five to ten years. They have all tasted at least fairly good, and have caused no problems. After all, I am here to relate this. Specific brands have been Tanka (buffalo jerky) and Clif (undifferentiated chemical compounds). I think the mylar wrapping has a good deal to do with these products remaining edible. I would suspect that most of the many other items packaged in the same manner would survive equally long.

As I understand the situation, "sell by"or "best by" dates do not relate to nutrition or nutritional value, but only to taste.