caption: Slide 2 of 30: Sweet potatoes are an excellent source of beta-carotene, which is found in orange-colored foods. The body converts the provitamin (a substance that is converted into a vitamin) into vitamin A, which helps boost the immune system, as well as eye health. It also helps reduce damage from free radicals and keeps the skin healthy -- skin is one of the first organs to fight off infection. ``Be sure to include the skin (of the sweet potato),'' <PERSON> said. ``It's the richest part of the vegetable when it comes to nutrition.''