Omega-3, omega-6, and total dietary polyunsaturated fat for prevention and treatment of type 2 diabetes mellitus: systematic review and meta-analysis of randomised controlled trials
Brown TJ, Brainard J, Song F, Wang X, Abdelhamid A, Hooper L, PUFAH Group
BMJ (Clinical research ed.) · 191 citations
How it was studied
- Design
- Meta-analysis (indexed by PubMed)
- Studied in
- People
- Main outcome
- Clinical events such as disease or death
Who paid for it
- Funding
- Independent funding
- University or hospital
- University of Pennsylvania
- University or hospital
- Pennsylvania State University
- University or hospital
- Virginia Commonwealth University
- University or hospital
- London School of Hygiene and Tropical Medicine
- University or hospital
- McMaster University
- University or hospital
- Istituto di Ricerche Farmacologiche Mario Negri - IRCCS
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- University of Southampton
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- University of Aberdeen
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- University of Bristol
- Government
- Commonwealth Scientific and Industrial Research Organisation
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- Rijksuniversiteit Groningen
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- University of Wollongong
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- Odense Universitetshospital
- University or hospital
- Royal Adelaide Hospital
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- Tehran University of Medical Sciences and Health Services
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- Università degli Studi di Pavia
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- National Institutes of Health (AREDS2)
Based on 22 listed funder(s).
Publication
- Published
- 2019-08-21 · BMJ · vol. 366 · p. l4697
- Cited
- 320 citations · more than 99% of similar papers · 7.9× the field average
- Impact
- Top 10% most cited in its field
- References
- 70 works
- Access
- Open access (hybrid journal) · CC-BY-NC
- Research areas
- Fatty Acid Research and Health · Nutritional Studies and Diet · Diet and metabolism studies
- Keywords
- Medicine, Diabetes mellitus, Internal medicine, Confidence interval, Relative risk, Meta-analysis, Randomized controlled trial, Type 2 diabetes, Insulin resistance, Polyunsaturated fatty acid, Insulin, Endocrinology, Fatty acid, Chemistry, Biochemistry
- MeSH
- humans, diabetes mellitus, type 2, insulin resistance, insulin, blood glucose, dietary fats, unsaturated, fatty acids, omega-3, fatty acids, unsaturated, fatty acids, omega-6, fasting, primary prevention, dietary supplements, adult, female, male, randomized controlled trials as topic, secondary prevention, glycated hemoglobin
6 authors
From GB
- Tracey J. Brown
- Julii Suzanne Brainard
- Fujian SongUniversity of East Anglia
- Xia WangUniversity of East Anglia
- Asmaa S AbdelhamidUniversity of East Anglia
- Lee Hooper · correspondingUniversity of East Anglia
Abstract
Objective
To assess effects of increasing omega-3, omega-6, and total polyunsaturated fatty acids (PUFA) on diabetes diagnosis and glucose metabolism.
Design
Systematic review and meta-analyses.
Data sources
Medline, Embase, Cochrane CENTRAL, WHO International Clinical Trials Registry Platform, Clinicaltrials.gov, and trials in relevant systematic reviews.
Eligibility criteria
Randomised controlled trials of at least 24 weeks' duration assessing effects of increasing α-linolenic acid, long chain omega-3, omega-6, or total PUFA, which collected data on diabetes diagnoses, fasting glucose or insulin, glycated haemoglobin (HbA1c), and/or homoeostatic model assessment for insulin resistance (HOMA-IR).
Data synthesis
Statistical analysis included random effects meta-analyses using relative risk and mean difference, and sensitivity analyses. Funnel plots were examined and subgrouping assessed effects of intervention type, replacement, baseline risk of diabetes and use of antidiabetes drugs, trial duration, and dose. Risk of bias was assessed with the Cochrane tool and quality of evidence with GRADE.
Results
83 randomised controlled trials (mainly assessing effects of supplementary long chain omega-3) were included; 10 were at low summary risk of bias. Long chain omega-3 had little or no effect on likelihood of diagnosis of diabetes (relative risk 1.00, 95% confidence interval 0.85 to 1.17; 58 643 participants, 3.7% developed diabetes) or measures of glucose metabolism (HbA1c mean difference -0.02%, 95% confidence interval -0.07% to 0.04%; plasma glucose 0.04, 0.02 to 0.07, mmol/L; fasting insulin 1.02, -4.34 to 6.37, pmol/L; HOMA-IR 0.06, -0.21 to 0.33). A suggestion of negative outcomes was observed when dose of supplemental long chain omega-3 was above 4.4 g/d. Effects of α-linolenic acid, omega-6, and total PUFA on diagnosis of diabetes were unclear (as the evidence was of very low quality), but little or no effect on measures of glucose metabolism was seen, except that increasing α-linolenic acid may increase fasting insulin (by about 7%). No evidence was found that the omega-3/omega-6 ratio is important for diabetes or glucose metabolism.
Conclusions
This is the most extensive systematic review of trials to date to assess effects of polyunsaturated fats on newly diagnosed diabetes and glucose metabolism, including previously unpublished data following contact with authors. Evidence suggests that increasing omega-3, omega-6, or total PUFA has little or no effect on prevention and treatment of type 2 diabetes mellitus.
Systematic review registration
PROSPERO CRD42017064110.
Abstract via Europe PMC. Copyright remains with the authors or publisher (CC BY-NC).
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