Review The combined effects of healthy lifestyle behaviors on all cause mortality: A systematic review and meta-analysis Martin Loef, Harald Walach ⁎ European University Viadrina, Institute of Transcultural Health Studies, Frankfurt/Oder, Germany Samueli Institute, European Office, Frankfurt (Oder), Germany abstract article info Available online 24 June 2012 Keywords: Lifestyle All-cause mortality Risk factors Cohort studies Objective. Lifestyle factors are related to mortality. Although much is known about the impact of single factors, the current evidence about the combined effects of lifestyle behaviors on mortality has not yet been systematically compiled. Method. We searched Medline, Embase, Global Health, and Somed up to February 2012. Prospective studies were selected if they reported the combined effects of at least three of five lifestyle factors (obesity, alcohol consumption, smoking, diet, and physical activity). The mean effect sizes that certain numbers of combined lifestyle factors have on mortality were compared to the group with the least number of healthy lifestyle factors by meta-analysis. Sensitivity analyses were conducted to explore the robustness of the results. Results. 21 studies (18 cohorts) met the inclusion criteria of which 15 were included in the meta-analysis that comprised 531,804 people with a mean follow-up of 13.24 years. The relative risks decreased propor- tionate to a higher number of healthy lifestyle factors for all cause mortality. A combination of at least four healthy lifestyle factors is associated with a reduction of the all cause mortality risk by 66% (95% confidence interval 58%–73%). Conclusion. Adherence to a healthy lifestyle is associated with a lower risk of mortality. © 2012 Elsevier Inc. All rights reserved. Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Data Sources and Searches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Study Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Data Extraction and Quality Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Data Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Statistical analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Role of the Funding Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Conflict of interest statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Introduction The risk of developing a major non-communicable disease, the leading cause of death in the world, is decisively affected by lifestyle choices (WHO, 2011a). Smoking, physical inactivity, unhealthy diet, obesity and other lifestyle behaviors are associated with the devel- opment of diseases such as cancer, heart disease, stroke, and diabetes (Lopez et al., 2006). Preventive Medicine 55 (2012) 163–170 ⁎ Corresponding author at: European University Viadrina, Institute of Transcultural Health Studies, Post Box 1786, D-15207 Frankfurt (Oder), Germany. Fax: +49 335 5534 2348. E-mail address: walach@europa-uni.de (H. Walach). 0091-7435/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.ypmed.2012.06.017 Contents lists available at SciVerse ScienceDirect Preventive Medicine journal homepage: www.elsevier.com/locate/ypmed