Use only holistic cat food

One of my very close friends is really disturbed these days as her cat passed away recently. She feels as if a member of her family has left her forever. The reason why she is extra disturbed is because she feels her cat had many more years to live, but passed away before her time because she was being given the wrong kind of pet food. It was during a discussion with me that she realized that most of the pet foods on the market contain steroids, preservatives, harmful chemicals, and other dangerous ingredients that do much more harm than good. And, she had been feeding such food to her cat. I told her that I feed my cat only holistic cat food, which is the same quality food that humans eat. When we take such care regarding what goes inside our bodies as humans, why should not our pets also be given the same?