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Effect of low-ratio n-6/n-3 PUFA on blood lipid level: a meta-analysis



The aim of this meta-analysis was to evaluate the effects of low-ratio n-6/n-3 PUFA on blood lipid levels.


We searched the PubMed, Embase, and Cochrane Library databases for randomized controlled trials of n-6/n-3 PUFA interventions up to March 2019. The change values were calculated as weighted mean differences (WMDs) by using a random-effect model. Subgroup analysis and meta-regression were used to explore the source of heterogeneity.


A total of 30 randomized controlled trials with 1368 participants were identified. Compared with control, low-ratio n-6/n-3 PUFA significantly reduced triglyceride (TG) concentration (WMD: − 0.079 mmol/L, 95% confidence interval (CI): − 0.148 mmol/L to − 0.009 mmol/L, p = 0.026) and increased high-density lipoprotein cholesterol (HDL-C) concentration (WMD: 0.033 mmol/L, 95% CI: 0.007 to 0.058 mmol/L, p = 0.012). Subgroup analysis revealed that the effects of low-ratio n-6/n-3 PUFA on blood lipid levels were better for a longer time. The effects of α-linolenic acid on total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) concentrations were more obvious among participants. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) had more significant effects on TG and HDL-C concentrations. No significant publication bias was observed for TG and HDL-C, as suggested by the results of Begg’s test and Egger’s test.


Low-ratio n-6/n-3 PUFA significantly reduced TG concentration and increased HDL-C concentration. The beneficial effects of low-ratio n-6/n-3 PUFA on TG, TC, HDL-C, and LDL-C concentrations were enhanced with time. However, n-3 PUFA derived from plants significantly reduced TC and LDL-C concentrations, and n-3 PUFA derived from EPA and DHA significantly reduced TG concentration and increased HDL-C concentration.

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Data availability

Some or all data, models, or code generated or used during the study are available from the corresponding author by request.


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I would like to extend my sincere gratitude to my supervisors, Tongcheng Xu and Hanxue Hou, for their instructive advice and useful suggestions on my thesis. I am also deeply indebted to all the other teachers and students for their help to me.


This work is supported by the National Key R&D Program of China (2018YFD0401104); by the Key R & D project of Shandong Province (2018YYSP011); by the Taishan Scholar Project (Feng-Hong Huang); and by the Key R & D project of Shandong Province (2019GHZ031). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Literature search: Na Li and Min Jia; methodology: Qianchun Deng; data statistics and analysis: Fenghong Huang and Min Jia; funding acquisition: Fenghong Huang, Tongcheng Xu; discussion analysis: Qianchun Deng and Tongcheng Xu; writing original draft: Na Li; writing review and editing: Hanxue Hou, Zhen Wang; approval of final manuscript: all authors.

Corresponding authors

Correspondence to Hanxue Hou or Tongcheng Xu.

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No animal and human experiments were involved in this study.

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We the undersigned declare that this manuscript entitled “The effect of low-ratio n-6/n-3 PUFA on blood lipid: a meta-analysis” is original, has not been published before, and is not currently being considered for publication elsewhere.

We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us.

The authors are the following: Na Li, Min Jia, Qianchun Deng, Zhen Wang, Fenghong Huang, Hanxue Hou, Tongcheng Xu.

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Li, N., Jia, M., Deng, Q. et al. Effect of low-ratio n-6/n-3 PUFA on blood lipid level: a meta-analysis. Hormones (2020).

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  • N-6/n-3 PUFA
  • Blood lipid
  • Randomized controlled trial
  • Meta-analysis