You can get lycopene from tomatoes, particularly cooked and stewed tomatoes, but “on a fresh basis, you can’t do better than watermelon,” said Penelope Perkins-Veazie, a professor at North Carolina State University in Raleigh who has studied lycopene and is an unpaid science adviser to the National Watermelon Promotion Board. Red watermelon has more lycopene than other watermelon varieties, and “seedless watermelon tends to have more,” she said.