Two kittens from the same litter go to different homes. One outlives the other by several years. Why is this?
Remember the old saying “You are what you eat?” This applies to cats too.
Take an extreme example: The cat fed on cheap, cereal-based cat food. When a diet is deficient in taurine, (such as some cat foods) this results in blindness and heart disease.
To thrive a cat needs a diet based on good quality meat proteins. Feed them a poor diet, with a high percentage of cereal and plant-based protein and this stresses their organs. Put the gut, liver, or kidneys under pressure and eventually, they will give up.
But even a meat-based food needs to be a balanced diet. Feeding meat alone leads to mineral imbalances that cause painful joints and weak bones. For long life, feed a well-balanced good quality pet food.