The fruit of the prickly pear cactus, known by the name cactus pear and prickly pear, is oval with a Dietary fiber is a complex carbohydrate found only in plant foods. Although your body can't digest fiber, it plays a crucial role in your health. These are great, and prickly pear cactus "fruits" (aka tunas) have some wonderful health benefits! You could also leave out the alcohol for a refreshing summer. In late summer in Mexico, prickly pear cactus fruits, or tunas, are everywhere—a refreshing snack eaten out of hand and a popular ingredient in.