Tomatoes contain a lot of vitamin A and vitamin K, as well as a significant amount of B vitamins, folic acid and thiamine. One tomato provides about 40% of the daily requirement for vitamin C. Tomatoes are also a good source of iron, potassium, manganese, magnesium, phosphorus and copper. It is especially important that tomatoes contain a number of organic compounds, for example, lycopene, the pigment responsible for the bright color of these fruits.