BLUE Longevity is the perfect food for your mature cat. It's a delicious blend of nutrient-rich foods with low caloric density that will satisfy your cats hunger, help prevent her from gaining unhealthy weight, and provide all of the nutrition she needs to enjoy life. What's more, Longevity Mature cat food helps support her specific needs with ingredients that have been shown to help with: lean muscle maintenance; energy to stay active; immune system health; healthy skin and coat; strong teeth and bones. Nutrient-Rich Ingredients. Lower Caloric Density. BLUE Longevity healthy cat food is a delicious blend of lean protein, nutrient-rich vegetables and fruits and wholesome whole grains.