Map of regions used in the analysis of regional differences in plasma α-tocopherol and blood selenium: Region 1: South-eastern Norway (Østfold, Akershus, Oslo, Hedmark, Oppland, Buskerud, Vestfold, Telemark, Aust-Agder and Vest-Agder counties). Region 2: Rogaland county. Region 3: Western Norway (Hordaland, Sogn og Fjordane and Møre og Romsdal counties). Region 4: Middle Norway (Sør-Trøndelag and Nord-Trøndelag counties). Region 5: Northern Norway (Nordland, Troms and Finnmark counties).