The aim of this paper isto determine factors associated with higher tobacco consumption in a large cohort of daily smoking Danish women 27–39 years of age with a main focus on the smoking habits of people in the women’s social environment and parity. A cohort of 12,023 Danish women was examined in a cross-sectional study design with a mailed questionnaire. Among the 3,672 daily smokers, 2,365 (64.4%) smoked more than 15 cigarettes per day. Smokers in the childhood home, living alone or cohabiting with a smoking partner, friends smoking, and colleagues smoking were associated with higher tobacco consumption, while short duration of smoking was associated with lower tobacco consumption. Anti-smoking programs should focus on the social network of the women. Furthermore, there is a need to target mothers who smoke, especially less educated mothers.

Obesity is driven by modifiable lifestyle factors whose effects may be mediated by epigenetics. Therefore, we investigated lifestyle effects (diet, physical activity, smoking and alcohol) on blood DNA methylation in participants of the LIFE-Adult study, a well-characterized population-based cohort from Germany. Fifty subjects with an extremely healthy and 50 with an extremely unhealthy lifestyle were selected for genome-wide DNA methylation analysis in blood samples. Whereas obesity was only marginally related to variability in DNA methylation pattern, comparisons between lifestyle categories resulted in 145 Differentially Methylated Positions (DMPs) and 4682 Differentially Methylated Regions (DMRs) annotated to 4426 unique genes. Intersection analysis showed that diet, physical activity, smoking and alcohol intake are equally contributing to the observed differences, which particularly affects pathways related to glutamatergic synapse and axon guidance. DNA methylation patterns help discriminate individuals with a healthy vs. unhealthy lifestyle, which may mask subtle methylation differences derived from obesity.