Institute of Public Health, Faculty of Health Sciences, Jagiellonian University Medical College, 31-531 Krakow, Poland. alicja.domagala@uj.edu.pl. Chair of Epidemiology and Preventive Medicine, Department of Hygiene and Dietetics, Faculty of Medicine, Jagiellonian University Medical College, 31-034 Krakow, Poland. malgorzata.1.bala@uj.edu.pl. Students' Scientific Group of Systematic Reviews, Systematic Reviews Unit-Polish Cochrane Branch, Jagiellonian University Medical College, 31-034 Krakow, Poland. dawstor@wp.pl. Department of Community Health and Epidemiology, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N5E5, Canada. juan.nicolas.ps@usask.ca. Students' Scientific Group of Systematic Reviews, Systematic Reviews Unit-Polish Cochrane Branch, Jagiellonian University Medical College, 31-034 Krakow, Poland. mefiu11@onet.eu. Students' Scientific Group of Systematic Reviews, Systematic Reviews Unit-Polish Cochrane Branch, Jagiellonian University Medical College, 31-034 Krakow, Poland. mati@sudety.info.pl. Systematic Reviews-Polish Cochrane Branch, Jagiellonian University Medical College, 31-034 Krakow, Poland monika.storman@wp.pl. monika.storman@wp.pl. Department of Diabetology and Internal Medicine, Medical University of Warsaw, 02-097 Warszawa, Poland. monika.storman@wp.pl.