Deeply colored fruits and vegetables tend to have the most vitamins and minerals. And besides that, the plant pigments that give them such rich colors may themselves protect against chronic diseases, including cancer. These pigments have high antioxidant potential. This doesn’t mean you shouldn’t bother with lightly colored fruits like green grapes or white potatoes. But do include some of the “darks” – such as kale, spinach, prunes, red grapes, raisins, cherries, oranges, and carrots – every day.
(Source: UC Berkeley Wellness Letter: Healthy Eating)