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Does omega‐3 fatty acids supplementation affect circulating leptin levels? A systematic review and meta‐analysis on randomized controlled clinical trials
Author(s) -
Hariri Mitra,
Ghiasvand Reza,
Shiranian Afshin,
Askari Gholamreza,
Iraj Bijan,
SalehiAbargouei Amin
Publication year - 2015
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/cen.12508
Subject(s) - meta analysis , randomized controlled trial , leptin , subgroup analysis , confidence interval , medicine , omega 3 fatty acid , body mass index , gastroenterology , strictly standardized mean difference , endocrinology , obesity , fatty acid , biology , polyunsaturated fatty acid , docosahexaenoic acid , biochemistry
Summary Background Omega‐3 fatty acids have attracted researchers for their effect on circulatory hormone‐like peptides affecting weight control. Objective Our objective was to conduct a systematic review and meta‐analysis on randomized controlled trials ( RCT s) assessed the effects of omega‐3 supplementation on serum leptin concentration and to find the possible sources of heterogeneity in their results. Methods We searched PubMed/Medline, Google Scholar, Ovid, SCOPUS and ISI web of science up to April 2014. RCT s conducted among human adults, examined the effect of omega‐3 fatty acid supplements on serum leptin concentrations as an outcome variable were included. The mean difference and standard deviation ( SD ) of changes in serum leptin levels were used as effect size for the meta‐analysis. Summary mean estimates with their corresponding SD s were derived using random effects model. Results Totally 14 RCT s were eligible to be included in the systematic review, and the meta‐analysis was performed on 13 articles. Our analysis showed that omega‐3 supplementation significantly reduces leptin levels (mean difference ( MD ) = −1·71 ng/ml 95% confidence interval ( CI ): −3·17 to −0·24, P = 0·022). Subgroup analysis based on BMI status showed that the omega‐3 supplementation reduces leptin when used for nonobese subjects ( MD = −3·60 ng/ml; 95% CI −6·23 to −0·90; P = 0·011); however, this was not true for obese participants ( MD = −0·86 ng/ml; 95% CI : −2·63 to −0·90; P = 0·296). Subgroup analysis based on omega‐3 source also showed that omega‐3 from marine sources may significantly reduce leptin levels ( MD = −1·73 ng/ml; 95% CI −3·25 to −0·2; P = 0·026), but plant sources do not significantly affect serum leptin levels ( MD = −1·48 ng/ml; 95% CI −6·78 to 3·23; P = 0·585). Our results were highly sensitive to one study. Conclusions Omega‐3 supplementation might moderately decrease circulatory leptin levels only among nonobese adults. RCT s with longer follow‐up period, using higher doses for obese adults and exploring the effect in different genders, are needed to replicate our results.