Nutraceutical or pharmaceutical compositions, functional foods, extracts, dietary supplements and food/feed additives enriched in phytochemicals having antioxidant and/or anti-inflammatory activity may be derived from the skin, pith, or cortex from stem tubers of select potato cultivars, including an Onaway potato cultivar optionally complemented by a Russet Burbank, Purple Valley or Bora Valley cultivar. These cultivars and combinations thereof provide a useful antioxidant source enriched in ferulic acid, caffeic acid, chlorogenic acids, ascorbic acid, anthocyanins, and rutin, isomers or derivatives thereof having antioxidant and/or anti-inflammatory activity.