Orange peels are richer in fiber, vitamins, and disease-fighting polyphenols than the actual fruit. They also contain limonene, a chemical that may protect against skin cancer.  Orange peel also contains good amounts of provitamin A, folate, riboflavin, thiamine, vitamin B6, and calcium.  Polyphenols may help prevent and manage many chronic conditions, such as type 2 diabetes, obesity, and Alzheimer's disease.