Hanna E. Bloomfield, MD, MPH; Eva Koeller, BA; Nancy Greer, PhD; Roderick MacDonald, MS; Robert Kane, MD; Timothy J. Wilt, MD, MPH
Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the U.S. government.
Financial Support: Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Quality Enhancement Research Initiative.
Disclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M16-0361.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that she has no financial relationships or interests to disclose. Darren B. Taichman, MD, PhD, Executive Deputy Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Deborah Cotton, MD, MPH, Deputy Editor, reports that she has no financial relationships or interest to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Catharine B. Stack, PhD, MS, Deputy Editor for Statistics, reports that she has stock holdings in Pfizer and Johnson & Johnson.
Reproducible Research Statement: Study protocol: Registered in PROSPERO (CRD42015020262) at www.crd.york.ac.uk/PROSPERO/. Statistical code: See Methods. Data set: Not available.
Requests for Single Reprints: Hanna E. Bloomfield, MD, MPH, Minneapolis VA Medical Center, 1 Veterans Drive (151), Minneapolis, MN 55417; e-mail, Hanna.Bloomfield@va.gov.
Current Author Addresses: Dr. Bloomfield: Minneapolis VA Medical Center, 1 Veterans Drive (151), Minneapolis, MN 55417.
Ms. Koeller, Drs. Greer and Wilt, and Mr. MacDonald: Minneapolis VA Medical Center, 1 Veterans Drive (111-O), Minneapolis, MN 55417.
Dr. Kane: University of Minnesota, Division of Public Health and Management, D351 Mayo MMC 729, 420 Delaware Street Southeast, Minneapolis, MN 55455.
Author Contributions: Conception and design: H.E. Bloomfield, N. Greer, R. Kane, T.J. Wilt.
Analysis and interpretation of the data: H.E. Bloomfield, E. Koeller, N. Greer, R. MacDonald, R. Kane, T.J. Wilt.
Drafting of the article: H.E. Bloomfield, R. MacDonald.
Critical revision for important intellectual content: H.E. Bloomfield, N. Greer, R. Kane, T.J. Wilt.
Final approval of the article: H.E. Bloomfield, E. Koeller, N. Greer, R. MacDonald, R. Kane, T.J. Wilt.
Provision of study materials or patients: E. Koeller, N. Greer.
Statistical expertise: R. MacDonald, T.J. Wilt.
Obtaining of funding: T.J. Wilt.
Administrative, technical, or logistic support: E. Koeller, N. Greer, T.J. Wilt.
Collection and assembly of data: H.E. Bloomfield, E. Koeller, N. Greer, T.J. Wilt.
Mediterranean diets may be healthier than typical Western diets.
To summarize the literature comparing a Mediterranean diet with unrestricted fat intake with other diets regarding their effects on health outcomes in adults.
Ovid MEDLINE, CINAHL, and the Cochrane Library from 1990 through April 2016.
Controlled trials of 100 or more persons followed for at least 1 year for mortality, cardiovascular, hypertension, diabetes, and adherence outcomes, as well as cohort studies for cancer outcomes.
Data extracted by 1 investigator was verified by another. Two reviewers assessed risk of bias and strength of evidence.
Two primary prevention trials found no difference in all-cause mortality between diet groups. One large primary prevention trial found that a Mediterranean diet resulted in a lower incidence of major cardiovascular events (hazard ratio [HR], 0.71 [95% CI, 0.56 to 0.90]), breast cancer (HR, 0.43 [CI, 0.21 to 0.88]), and diabetes (HR, 0.70 [CI, 0.54 to 0.92]). Pooled analyses of primary prevention cohort studies showed that compared with the lowest quantile, the highest quantile of adherence to a Mediterranean diet was associated with a reduction in total cancer mortality (risk ratio [RR], 0.86 [CI, 0.82 to 0.91]; 13 studies) and in the incidence of total (RR, 0.96 [CI, 0.95 to 0.97]; 3 studies) and colorectal (RR, 0.91 [CI, 0.84 to 0.98; 9 studies]) cancer. Of 3 secondary prevention studies reporting cardiovascular outcomes, 1 found a lower risk for recurrent myocardial infarction and cardiovascular death with the Mediterranean diet. There was inconsistent, minimal, or no evidence pertaining to any other outcome, including adherence, hypertension, cognitive function, kidney disease, rheumatoid arthritis, and quality of life.
Few trials; medium risk-of-bias ratings for many studies; low or insufficient strength of evidence for outcomes; heterogeneous diet definitions and components.
Limited evidence suggests that a Mediterranean diet with no restriction on fat intake may reduce the incidence of cardiovascular events, breast cancer, and type 2 diabetes mellitus but may not affect all-cause mortality.
Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Quality Enhancement Research Initiative. (PROSPERO: CRD42015020262)
Bloomfield HE, Koeller E, Greer N, MacDonald R, Kane R, Wilt TJ. Effects on Health Outcomes of a Mediterranean Diet With No Restriction on Fat Intake: A Systematic Review and Meta-analysis. Ann Intern Med. [Epub ahead of print 19 July 2016]165:491–500. doi: 10.7326/M16-0361
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Published: Ann Intern Med. 2016;165(7):491-500.
Published at www.annals.org on 19 July 2016
Cardiology, Hematology/Oncology, Prevention/Screening, Rheumatoid Arthritis, Rheumatology.
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