Many cats love olives because they contain compounds known as isoprenoids, which are chemically similar to the active ingredient in catnip. Isoprenoids are primarily found in pimentos and different varieties of green olives, such as Kalamatas.
The isoprenoids found in olives are structurally similar to methylcyclopentane monoterpene nepetalactone, the active chemical in catnip. This chemical binds to receptors in a cat's vomeronasal organ, which is also where catnip takes effect. Cats, along with most other animals aside from humans, primarily use the vomeronasal organ to sense pheromones. The pleasurable effect on the receptors accounts for many cats' love of both catnip and certain types of olives. Normally reserved cats may demonstrate out-of-character behavior, such as screaming or begging, when confronted with olives; however, the pleasurable effects that stem from consuming olives may not affect all cats.
Cat behaviorist and television host Jackson Galaxy reports that consuming olives has no detrimental effect on cats though the food offers little nutritional value for felines. Some owners report diarrhea in cats that frequently consume olives. Although olives are an acceptable treat on occasion, pet radio host Tracie Hotchner suggests that a more enriching method of treating cats is to place freeze-dried protein treats inside a toy dispenser. Attempting to free the treats provides productive environmental stimulation for cats.