Traditional lifestyle factors partly mediate the association of socioeconomic position with intrahepatic lipid content: The Maastricht study
Zhewen Ren,
Hans Bosma,
Anke Wesselius,
Simone J.P.M. Eussen,
M. Eline Kooi,
Carla J.H. van der Kallen,
Annemarie Koster,
Marleen M.J. van Greevenbroek,
Pieter Dagnelie,
Coen D.A. Stehouwer,
Martijn C.G.J. Brouwers
Affiliations
Zhewen Ren
Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Laboratory for Metabolism and Vascular Medicine, Maastricht University, Maastricht, The Netherlands
Hans Bosma
Department of Social Medicine, Maastricht University, Maastricht, The Netherlands; CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands
Anke Wesselius
Department of Epidemiology, Maastricht University, Maastricht, The Netherlands; NUTRIM School for Nutrition and Translational Research in Metabolism Maastricht University, Maastricht, The Netherlands
Simone J.P.M. Eussen
CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Department of Epidemiology, Maastricht University, Maastricht, The Netherlands; NUTRIM School for Nutrition and Translational Research in Metabolism Maastricht University, Maastricht, The Netherlands
M. Eline Kooi
CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands
Carla J.H. van der Kallen
Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
Annemarie Koster
Department of Social Medicine, Maastricht University, Maastricht, The Netherlands; CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands
Marleen M.J. van Greevenbroek
CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Laboratory for Metabolism and Vascular Medicine, Maastricht University, Maastricht, The Netherlands
Pieter Dagnelie
Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
Coen D.A. Stehouwer
Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
Martijn C.G.J. Brouwers
Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands; CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; CAPHRI Care and Public Health Research Institute, Maastricht University, Maastricht, The Netherlands; Corresponding author. Address: Department of Internal Medicine, Division of Endocrinology and Metabolic Diseases, Maastricht University Medical Center, PO Box 5800, 6202 AZ Maastricht, The Netherlands. Tel.: +31 433877019.
Background & Aims: Recent studies have unveiled an association between socioeconomic position (SEP) and intrahepatic lipid (IHL) content. The aim of this study was to examine to what extent traditional lifestyle factors mediate the relationship between SEP and IHL content, independent of aetiology, and non-alcoholic fatty liver disease (NAFLD). Methods: We used cross-sectional data derived from The Maastricht Study (N = 4,001; mean age: 60 years, 49% women, 32% low education level, 21% diabetes, 21% NAFLD). Education, income, and occupation were used as indicators of SEP. Physical activity (accelerometer), intake of total energy, alcohol, saturated fat, protein, vitamin E, dietary fibre, and fructose from sugar-sweetened beverages (SSBs) and fruit juice (food frequency questionnaires) were potential mediators. IHL content was quantified by magnetic resonance imaging. Age, sex, and type 2 diabetes were covariates. Multiple parallel mediation analyses (bootstraps = 10,000) were performed. Results: Individuals with a low education level had a 1.056-fold higher IHL content (95% CI: 1.03–1.08) and a 44% greater NAFLD risk (OR:1.44; 95% CI:1.18–1.77) compared with those with higher education levels. Approximately 8.9% of educational disparity in risk of IHL content was attributable to moderate-to-vigorous physical activity; 6.3% to fructose intake from SSBs; 5.5% to dietary fibre; and -23% to alcohol. Approximately 8.7% of educational disparity in risk of NAFLD was attributable to moderate-to-vigorous physical activity; and 7.7% to fructose intake from SSBs. However, the indirect effect of these mediators was small (0.998 for IHL content and 1.045 for NAFLD) in comparison to the total effect. Similar results were found when income and occupation were used as SEP indicators. Conclusions: Societal measures may alleviate the burden of NAFLD and further studies that identify mediators other than traditional lifestyle factors are warranted to define the relationship underlying SEP and IHL content. Impact and implications: Individuals with a low or medium level of education, income, or occupational status had more fat accumulation in their livers than individuals with a higher education, income, or occupational status. This difference may be attributed to the influence of unhealthy lifestyle factors, such as reduced physical activity and a higher intake of sugar-sweetened beverages among individuals with lower socioeconomic position. Nevertheless, other yet unknown factors may also play a role.
