While your cat may safely eat tomatoes. The toxic part of the tomato plant Such as the leaves and stems. These parts of the plants are very toxic to cats. Because these parts have the presence of the glycoalkaloid called solanine. Solanine is also present in plants. They are under the Solanaceae family such as eggplant, paprika, and peppers. You should keep an eye on your cat if you have house plants