Our foods are freeze dried in a unique process where we slowly lower the temperature then remove the water (which has turned into ice) by sublimation. This retains over 90% of the nutrients and leaves the food shelf stable for 25 years without need of any preservatives. This is preferable to dehydrated food which uses heat to remove water and destroys up to 50% of the nutrients. If opened and kept in a cool, dark environment with the plastic lid on, Nutrient Survival is good for 9-12 months. (Note: The bars and cookies contain syrup which may harden over time. The recommended shelf life is 18 months. They do not spoil, but they will be hard to bite into after that!).