Digestive shock can be a major problem during survival situations. Eating foods that are completely unfamiliar, especially while under additional stress, can cause your digestive system to revolt. Digestive shock systems can range from mild indigestion to severe vomiting, diarrhea, or even allergic reactions. For this reason you should never use foods you haven't eat before in either a bug-out bag or as part of your long-term food stores. Ideally you should store foods that you eat on a regular basis to provide as much continuity as possible.