Watermelon: The watermelon, as a whole, is one of the healthiest fruits on the planet. Its seeds contain zinc, iron, and fiber, and can be composed of up to 30% protein. The outer skin is not exceptionally nutritious, but the rind definitely is, containing vitamins A and C, beta-carotene, and lycopene, an especially beneficial phytonutrient that studies suggest may serve as a preventative for certain cancers such as prostate cancer.