Tomatoes are loaded with a substance called lycopene. It gives them their bright red color and helps protect them from the sun's ultraviolet rays. In much the same way, it can help protect your cells from damage.
Lycopene is an antioxidant -- it fights molecules called free radicals that can damage your cells and affect your immune system. Because of that, foods high in lycopene, like tomatoes, may make you less likely to have lung, stomach, or prostate cancer. Tomatoes also have potassium, vitamins B and E, and other nutrients.
Other nutrients in tomatoes, like vitamins B and E and antioxidants called flavonoids, may boost your heart health, too. Some research shows they might also help prevent the disease in the pancreas, colon, throat, mouth, breast, and cervix. Lycopene may also help lower your LDL, or "bad" cholesterol, and blood pressure levels. And that may reduce your chances of heart disease.
Source: https://www.webmd.com/food-recipes/ss/slideshow-tomato-health-benefits