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Creation of a database to assess effects of omega-3, omega-6 and total polyunsaturated fats on health: methodology for a set of systematic reviews

Hooper L, Abdelhamid A, Brainard J, Deane KHO, Song F, PUFAH group

BMJ open, 2019

Abstract

OBJECTIVE: To create a database of long-term randomised controlled trials (RCTs) comparing higher with lower omega-3, omega-6 or total polyunsaturated fatty acid (PUFA), regardless of reported outcomes, and to develop methods to assess effects of increasing omega-6, alpha-linolenic acid (ALA), long-chain omega-3 (LCn3) and total PUFA on health outcomes.

DESIGN: Systematic review search, methodology and meta-analyses.

DATA SOURCES: Medline, Embase, CENTRAL, WHO International Clinical Trials Registry Platform, Clinicaltrials.gov and trials in relevant systematic reviews.

ELIGIBILITY CRITERIA: RCTs of ≥24 weeks' duration assessing effects of increasing ALA, LCn3, omega-6 or total PUFAs, regardless of outcomes reported.

DATA SYNTHESIS: Methods included random-effects meta-analyses and sensitivity analyses. Funnel plots were examined, and subgrouping assessed effects of intervention type, replacement, baseline diabetes risk and use of diabetic medications, trial duration and dose. Quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS: Electronic searches generated 37 810 hits, de-duplicated to 19 772 titles and abstracts. We assessed 2155 full-text papers, conference abstracts and trials registry entries independently in duplicate. Included studies were grouped into 363 RCTs comparing higher with lower omega-3, omega-6 and/or total PUFA intake of at least 6 months' duration-the Database.Of these 363 included…

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