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Cardiac risk factors and prevention
Original research
The effect of green Mediterranean diet on cardiometabolic risk; a randomised controlled trial
  1. Gal Tsaban1,2,
  2. Anat Yaskolka Meir1,
  3. Ehud Rinott1,
  4. Hila Zelicha1,
  5. Alon Kaplan1,
  6. Aryeh Shalev3,
  7. Amos Katz1,
  8. Assaf Rudich1,
  9. Amir Tirosh4,5,
  10. Ilan Shelef6,
  11. Ilan Youngster7,8,
  12. Sharon Lebovitz1,
  13. Noa Israeli1,
  14. May Shabat1,
  15. Dov Brikner9,
  16. Efrat Pupkin9,
  17. Michael Stumvoll10,
  18. Joachim Thiery11,
  19. Uta Ceglarek10,
  20. John T Heiker10,
  21. Antje Körner10,
  22. Kathrin Landgraf10,
  23. Martin von Bergen12,13,
  24. Matthias Blüher10,
  25. Meir J Stampfer5,14,
  26. Iris Shai1,5
  1. 1 Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
  2. 2 Department of Medicine, Soroka University Medical Center, Beer Sheva, Israel
  3. 3 Department of Cardiology, Soroka University Medical Center, Beer Sheva, Israel
  4. 4 Division of Endocrinology, Diabetes and Metabolism, Sheba Medical Center at Tel Hashomer, Tel Hashomer, Israel
  5. 5 Harvard University T H Chan School of Public Health, Boston, Massachusetts, USA
  6. 6 Division of Diagnostic and Interventional Imaging, Soroka University Medical Center, Beer Sheva, Israel
  7. 7 Center for Microbiome Research, Yitzhak Shamir Medical Center Assaf Harofeh, Zerifin, Israel
  8. 8 Tel Aviv University Sackler Faculty of Medicine, Tel Aviv, Israel
  9. 9 Department of Medicine, Nuclear Research Centre Negev, Beer-Sheva, Israel
  10. 10 Department of Medicine, Leipzig University, Leipzig, Germany
  11. 11 University of Leipzig, Leipzig, Germany
  12. 12 Faculty of Life Sciences, Leipzig University, Leipzig, Germany
  13. 13 Department of Molecular Systems Biology, Helmholtz-Centre for Environmental Research - UFZ, Leipzig, Germany
  14. 14 Brigham and Women's Hospital Channing Division of Network Medicine, Boston, Massachusetts, USA
  1. Correspondence to Dr Iris Shai, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel; irish{at}bgu.ac.il

Abstract

Background A Mediterranean diet is favourable for cardiometabolic risk.

Objective To examine the residual effect of a green Mediterranean diet, further enriched with green plant-based foods and lower meat intake, on cardiometabolic risk.

Methods For the DIRECT-PLUS parallel, randomised clinical trial we assigned individuals with abdominal obesity/dyslipidaemia 1:1:1 into three diet groups: healthy dietary guidance (HDG), Mediterranean and green Mediterranean diet, all combined with physical activity. The Mediterranean diets were equally energy restricted and included 28 g/day walnuts. The green Mediterranean diet further included green tea (3–4 cups/day) and a Wolffia globosa (Mankai strain; 100 g/day frozen cubes) plant-based protein shake, which partially substituted animal protein. We examined the effect of the 6-month dietary induction weight loss phase on cardiometabolic state.

Results Participants (n=294; age 51 years; body mass index 31.3 kg/m2; waist circumference 109.7 cm; 88% men; 10 year Framingham risk score 4.7%) had a 6-month retention rate of 98.3%. Both Mediterranean diets achieved similar weight loss ((green Mediterranean −6.2 kg; Mediterranean −5.4 kg) vs the HDG group −1.5 kg; p<0.001), but the green Mediterranean group had a greater reduction in waist circumference (−8.6 cm) than the Mediterranean (−6.8 cm; p=0.033) and HDG (−4.3 cm; p<0.001) groups. Stratification by gender showed that these differences were significant only among men. Within 6 months the green Mediterranean group achieved greater decrease in low-density lipoprotein cholesterol (LDL-C; green Mediterranean −6.1 mg/dL (−3.7%), −2.3 (-0.8%), HDG −0.2 mg/dL (+1.8%); p=0.012 between extreme groups), diastolic blood pressure (green Mediterranean −7.2 mm Hg, Mediterranean −5.2 mm Hg, HDG −3.4 mm Hg; p=0.005 between extreme groups), and homeostatic model assessment for insulin resistance (green Mediterranean −0.77, Mediterranean −0.46, HDG −0.27; p=0.020 between extreme groups). The LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio decline was greater in the green Mediterranean group (−0.38) than in the Mediterranean (−0.21; p=0.021) and HDG (−0.14; p<0.001) groups. High-sensitivity C-reactive protein reduction was greater in the green Mediterranean group (−0.52 mg/L) than in the Mediterranean (−0.24 mg/L; p=0.023) and HDG (−0.15 mg/L; p=0.044) groups. The green Mediterranean group achieved a better improvement (−3.7% absolute risk reduction) in the 10-year Framingham Risk Score (Mediterranean−2.3%; p=0.073, HDG−1.4%; p<0.001).

Conclusions The green MED diet, supplemented with walnuts, green tea and Mankai and lower in meat/poultry, may amplify the beneficial cardiometabolic effects of Mediterranean diet.

Trial registration number This study is registered under ClinicalTrials.gov Identifier no NCT03020186.

  • obesity
  • metabolic syndrome
  • cardiac risk factors and prevention

Data availability statement

Data are available upon reasonable request. Data may be obtained from a third party and are not publicly available. All data of the trial are stored in an encrypted file on the Ben-Gurion University protected servers. Data may be available upon request and approval of the study’s principal investigator (Shai I).

https://doi.org/10.1136/heartjnl-2020-317802

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    Data availability statement

    Data are available upon reasonable request. Data may be obtained from a third party and are not publicly available. All data of the trial are stored in an encrypted file on the Ben-Gurion University protected servers. Data may be available upon request and approval of the study’s principal investigator (Shai I).

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    Footnotes

    • Twitter @GalTsaban

    • GT and AYM contributed equally.

    • Correction notice This article has been corrected since it was published Online First. The reported numbers for changes in Triglycerides were updated.

    • Contributors IrS, GT, and AYM designed the research, conducted the study, analysed the data, wrote the manuscript, and are responsible for final content. IrS, AR, AT, and MJS conceived and designed the research. HZ, AKa, and ER designed the research. MSt, JT, UC, JH, AKö, KL, MvB, and MB analysed the data. HZ, AKa, SL, MSh, NI, ER, DB, and EP conducted the study. AS, AKa, AR, AT, IlS, IY, and MJS reviewed and edited the manuscript. All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis as well as for the decision to submit the manuscript for publication. The corresponding author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive license (or non-exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd and its Licensees to permit this article (if accepted) to be published in HEART editions and any other BMJPGL products to exploit all subsidiary rights.

    • Funding This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Projektnummer 209933838 – SFB 1052; the Deutsche Forschungsgemeinschaft, Obesity Mechanisms; the Israel Ministry of Health (grant no. 87472511), Israel Ministry of Science and Technology (grant 3-13604); and the California Walnuts Commission. None of the foundations was involved in any stage of the design, conduct, or analysis of the study and had no access to the study results before publication.

    • Competing interests IrS advises the nutritional committee of Hinoman, Ltd. All other authors have no relevant conflict of interest to disclose.

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

    • 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.