Abstract

Global DNA methylation in peripheral blood cells is considered a potential surrogate biomarker of systemic genome methylation and has been associated with increased risk of several cancers including breast cancer. The impact of lifestyle on DNA methylation have not been well characterised yet, although it has been suggested that environmental factors may affect the level of DNA methylation.

The aim was to analyse association between global DNA methylation, selected lifestyle factors and obesity among nurses and midwives by their work system.

The study included 347 current rotating nights and 363 current day nurses and midwives, aged 40–60 years. Information about smoking, alcohol drinking and physical activity and diet were collected via in person interview, body weight, height and hip and waist circumferences were measured. Global DNA methylation in human leukocytes was determined by means of DNA quantification using 5-methylcytosine monoclonal antibodies in ELISA-like reaction (Epigentek, Farmingdale, NY, USA). Linear regression analyses were carried out with global DNA methylation as dependent variable and current smoking, packyears, average alcohol drinking, total number of years of alcohol drinking, drinkyears, total physical activity, recreational physical activity, BMI (body mass index), WHR (waist to hip ratio), and WHtR(waist to height ratio) as independent variables adjusted for age and folates intake.

Global DNA methylation showed statistically significant positive association with lifelong duration of alcohol drinking (β coef.: 0.01, 95% CI: 0.001–0.02), but not other measures of alcohol consumption. Borderline (0.1 > p > 0.05) inverse association was noted with obesity (BMI > 30 kg/m2) (β – coef.: −0.15, 95% CI: −0.30–0.01), but not with abdominal obesity. Smoking and physical activity were not associated with global DNA methylation. No significant results were found when analyses were run separately in categories of women by system of their work.

The study found no strong associations between lifestyle or obesity and global DNA methylation.