The explanation of educational disparities in adiposity by lifestyle, socioeconomic and mental health mediators
Authors: Bartoskova Polcrova A , Ksinan A J , Gonzalez-Rivas J P , Bobak M , Pikhart H 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 857487 (R-Exposome Chair) and National Institute for Research of Metabolic and Cardiovascular Diseases (Programme EXCELES, ID Project No. LX22NPO5104) - Funded by the European Union – Next Generation EU.

Background
The inverse association between education and obesity was previously found in numerous studies. However, education level per se is not directly related to obesity. Instead, other factors linked to educational disadvantage are likely to serve as mediators of the association. Lower educational levels are associated with poor lifestyle, economic disadvantage, and mental health problems, which all are risk factors of increased adiposity.

Purpose
We hypothesize the potential mediating role of lifestyle, socioeconomic and mental health factors in the association between education and increased adiposity, thus this study aims to assess diverse mediators in the educational disparities in adiposity.

Methods
Cross-sectional population-based sample from Czechia included 2154 25-64 years old subjects (2013-2014, 54.6% women). Educational attainment was classified as high, middle, and low. Adiposity was assessed as a latent variable constructed based on four main available adiposity biomarkers - body fat percentage, BMI, waist circumference, and visceral fat. The mediation potential of 8 factors (unhealthy dietary behaviour, alcohol intake, smoking, sedentary behaviours, income, stress, depression, and quality of life) was assessed in age-adjusted sex-specific simple and multiple mediation models.

Results
The negative direct effect of education on adiposity was significant in all investigated models. In a simple mediation model (each potential mediator tested separately), in men, the indirect effect significantly operated via sedentary behaviour, while in women via dietary risk, alcohol consumption, sedentary behaviour, income, and mental health. In multiple mediation models (all potential mediators tested in a one set), in men, the indirect effect was significant via sedentary behavior (β=0.041; 95% CI [0.025-0.062]) with a mediation ratio of 23.7%. In women, the indirect effect was significant via dietary risk (β=-0.023, 95% CI [-0.037, -0.013]), alcohol intake (β=-0.006; 95% CI [-0.014, -0.001]), sedentary behavior (β=0.012, 95% CI [0.004,0.023]), income (β=-0.022; 95% CI [-0.041, -0.004]), and mental health (β=-0.007; 95% CI [-0.019, -0.001]). The total mediation ratio in women was 30.5%.

Conclusions
Sedentary behaviours mediated the protective potential of higher educational levels on adiposity in both sexes, with a higher magnitude in men. In addition, unhealthy diet and lower income partially mediated the educational gradient in women. Reducing sedentary time should be targeted in public health strategies to reduce the burden of increased adiposity. Future studies should investigate a broader spectrum of potential mediators including knowledge-related factors and components of external environment.