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Epidemiology
Original research
Prospective association between adherence to the Mediterranean diet and hepatic steatosis: the Swiss CoLaus cohort study
  1. Saman Khalatbari-Soltani1,2,3,
  2. Pedro Marques-Vidal3,
  3. Fumiaki Imamura4,
  4. Nita G. Forouhi4
  1. 1Faculty of Medicine and Health, The University of Sydney School of Public Health, Sydney, New South Wales, Australia
  2. 2ARC Centre for Excellence in Population Ageing Research (CEPAR), University of Sydney, Sydney, New South Wales, Australia
  3. 3Department of Internal Medicine, Internal Medicine, University Hospital of Lausanne (CHUV), Lausanne, Switzerland
  4. 4Medical Research Council Epidemiology Unit, University of Cambridge, School of Clinical Medicine, Cambridge, UK
  1. Correspondence to Dr Saman Khalatbari-Soltani; saman.khalatbarisoltani{at}sydney.edu.au; Professor Nita G. Forouhi; nita.forouhi{at}mrc-epid.cam.ac.uk

Abstract

Objective The Mediterranean diet has been promoted as a healthy dietary pattern, but whether the Mediterranean diet may help to prevent hepatic steatosis is not clear. This study aimed to evaluate the prospective association between adherence to the Mediterranean diet and risk of hepatic steatosis.

Design Population-based prospective cohort study.

Setting The Swiss CoLaus Study.

Participants We evaluated 2288 adults (65.4% women, aged 55.8±10.0 years) without hepatic steatosis at first follow-up in 2009–2012. Adherence to the Mediterranean diet was scaled as the Mediterranean diet score (MDS) based on the Mediterranean diet pyramid ascertained with responses to Food Frequency Questionnaires.

Outcome measures New onset of hepatic steatosis was ascertained by two indices separately: the Fatty Liver Index (FLI, ≥60 points) and the non-alcoholic fatty liver disease (NAFLD) score (≥−0.640 points). Prospective associations between adherence to the Mediterranean diet and risk of hepatic steatosis were quantified using Poisson regression.

Results During a mean 5.3 years of follow-up, hepatic steatosis was ascertained in 153 (6.7%) participants by FLI criteria and in 208 (9.1%) by NAFLD score. After multivariable adjustment, higher adherence to MDS was associated with lower risk of hepatic steatosis based on FLI: risk ratio 0.84 (95% CI 0.73 to 0.96) per 1 SD of MDS; 0.85 (0.73 to 0.99) adjusted for BMI; and 0.85 (0.71 to 1.02) adjusted for both BMI and waist circumference. When using NAFLD score, no significant association was found between MDS and risk of hepatic steatosis (0.95 (0.83 to 1.09)).

Conclusion A potential role of the Mediterranean diet in the prevention of hepatic steatosis is suggested by the inverse association observed between adherence to the Mediterranean diet and incidence of hepatic steatosis based on the FLI. The inconsistency of this association when hepatic steatosis was assessed by NAFLD score points to the need for accurate population-level assessment of fatty liver and its physiological markers.

  • nutrition & dietetics
  • epidemiology
  • public health
  • hepatology
https://creativecommons.org/licenses/by/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

https://doi.org/10.1136/bmjopen-2020-040959

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    Footnotes

    • FI and NGF are joint senior authors.

    • Twitter @Saamaankh

    • FI and NGF contributed equally.

    • Contributors SK-S, FI and NGF designed the study question, and had full access to all the data in the study and took responsibility for the integrity and accuracy of the data. SK-S performed the statistical analyses and wrote the first draft with supervision from FI, PM-V and NGF. All authors contributed to interpretation of data, revised the article critically for important intellectual content and approved the final version of the manuscript.

    • Funding The CoLaus Study was and is supported by research grants from GlaxoSmithKline, the Faculty of Biology and Medicine of Lausanne, and the Swiss National Science Foundation (grants 33CSCO-122661, 33CS30-139468 and 33CS30-148401). SK-S was supported by the Swiss National Science Foundation (Doc.Mobility number P1LAP3-171805). NGF and FI acknowledge core MRC support (MC_UU_12015/5), and NGF acknowledges NIHR Biomedical Research Centre Cambridge: Nutrition, Diet and Lifestyle Research Theme (IS-BRC-1215-20014).

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval The Institutional Ethics Committee of the University of Lausanne, which afterwards became the Ethics Commission of Canton Vaud (www.cer-vd.ch) approved the baseline CoLaus Study (reference 16/03); the approval was renewed for the first (reference 33/09) and the second (reference 26/14) follow-ups. The CoLaus Study was performed in agreement with the Helsinki Declaration and its former amendments, and all participants provided their written informed consent before entering the study.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data are available upon reasonable request. Non-identifiable individual-level data are available for researchers who seek to answer questions related to health and disease in the context of research projects who meet the criteria for data sharing by research committees. Please follow the instructions at https://www.colaus-psycolaus.ch/ for information on how to submit an application for gaining access to CoLaus data.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.