[1] Natl Publ Hlth Inst, Dept Epidemiol & Hlth Promot, Unit Nutr, SF-00300 Helsinki, Finland
[2] Univ Tampere, Tampere Sch Publ Hlth, FIN-33101 Tampere, Finland
[3] Univ Helsinki, Hosp Children & Adolescents, FIN-00014 Helsinki, Finland
[4] Univ Oulu, Dept Paediat, Oulu, Finland
[5] Inst Child Hlth, Dept Paediat Epidemiol & Biostat, London, England
[6] Tampere Univ Hosp, Dept Paediat, Tampere, Finland
[7] Tampere Univ Hosp, Res Unit, Tampere, Finland