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Abstract
The objective of this meta-analysis was to investigate the effects of plant-derived polyunsaturated fatty acids (PUFAs) on glucose metabolism and insulin resistance. Scopus and PubMed databases were searched until January 2018. Eligible studies were randomized controlled feeding trials that investigated the effects of a diet high in plant-derived PUFA as compared with saturated fatty acids (SFA) or carbohydrates and measured markers of glucose metabolism and insulin resistance as outcomes. Data from 13 relevant studies (19 comparisons of plant-derived PUFA with control) were retrieved. Plant-derived PUFA did not significantly affect fasting glucose (−0.01 mmol/L (95 % CI − 0.06 to 0.03 mmol/L)), but lowered fasting insulin by 2.6 pmol/L (−4.9 to −0.2 pmol/L) and homeostatic model assessment-insulin resistance (HOMA-IR) by 0.12 units (-0.23 to − 0.01 units). In dose–response analyses, a 5% increase in energy (En%) from PUFA significantly reduced insulin by 5.8 pmol/L (95% CI −10.2 to −1.3 pmol/L), but not glucose (change −0.07, 95% CI −0.17 to 0.04 mmol/L) and HOMA-IR (change − 0.24, 95% CI −0.56 to 0.07 units). In subgroup analyses, studies with higher PUFA dose (upper tertiles) reduced insulin (-6.7, –10.5 to −2.9 pmol/L) and HOMA-IR (-0.28, –0.45 to −0.12 units), but not glucose (−0.09, 95% CI −0.18 to 0.01 mmol/L), as compared with an isocaloric control. Subgroup analyses showed no differences in effects between SFA and carbohydrates as replacement nutrients (p interaction ≥0.05). Evidence from randomized controlled trials indicated that plant-derived PUFA as an isocaloric replacement for SFA or carbohydrates probably reduces fasting insulin and HOMA-IR in populations without diabetes.
- glucose metabolism
- meta-analysis
- dietary fat
- insulin resistance
- Linoleic acid
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Footnotes
Contributors AJW, WAMB, MA conceived the study. AJW, WAMB, PLZ, JMG, IAB, MA designed the study. AJW analyzed the data and drafted the manuscript. All authors contributed to the writing of the manuscript, agree with the manuscript’s results, conclusions and final version of the manuscript. All authors have read and confirm that they meet ICMJE criteria for authorship.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests The authors of this manuscript have the following competing interests: AJW, WAMB, PLZ, MA are employed by Unilever, Vlaardingen, the Netherlands. Unilever markets food products made of vegetable oils such as dressings. Unilever has divested its spreads business, which is since July 2, 2018 operating under the name Upfield™. JMG received research funding from Unilever for studies on fatty acids and cardiovascular disease. IAB supervises a student whose project is partly funded by Unilever.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data are provided in supplemental files. No additional data are available.