Spinach. Eating spinach on a daily basis, like the other vegetables on this list, is a healthy practice, but eating too much can be harmful. Spinach includes oxalates, which bind to iron and calcium, rendering them inactive physiologically. Consuming too much spinach may also raise your chances of developing a kidney stone. However, most of the danger associated with spinach comes from its oxalate content, so if you're able to limit yourself to only three servings per week, it should not cause problems for your health. The only way not to eat any bad food is not to eat anything at all, because nothing counts as "bad" or "good." If you exclude everything, then you'll die before you reach old age. And even if you do manage to survive by avoiding any particular category of food, you'll be in big trouble when it comes time to move to another country, because then you'll need to avoid all the foods in this country too. Some people think that tomatoes are poisonous. This is not true; however, they do contain acid compounds that can irritate your stomach lining. Also, unlike most fruits which provide essential nutrients for your body, tomatoes contain a high amount of acid which does not help your body's ability to process food efficiently. Therefore, it's best to eat tomatoes in small quantities every now and then. Grapes are very acidic and their consumption should be limited to occasional treats.