In 2004, USDA scientists investigated over 100 foods to measure their antioxidant concentration per serving size. Two apples—Red Delicious and Granny Smith—ranked 12th and 13th respectively. Antioxidants are disease-fighting compounds. Scientists believe these compounds help prevent and repair oxidation damage that happens during normal cell activity. Apples are also full of a fibre called pectin—a medium-sized apple contains about 4 grams of fibre. Pectin is classed as a soluble, fermentable and viscous fibre, a combination that gives it a huge list of health benefits.