Whether you're eating it boiled or raw, it's important to include the outermost savoy cabbage leaves. Many people discard them but that's a mistake, as most of the antioxidants in cabbage are found in the outer and darker leaves. The inner core has very little nutritional value as it's more or less just fiber and water.
ORAC Source
USDA Database for the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2 - Prepared by Nutrient Data Laboratory, Beltsville Human Nutrition Research Center (BHNRC), Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA) - May 2010