Fish oil supplementation moderately increases circulating adiponectin, according to a review published in the Journal of Clinical Endocrinology & Metabolism.

Jason H.Y. Wu, Ph.D., from Harvard University in Boston, and colleagues conducted a literature review and meta-analysis of randomized placebo-controlled clinical trials (RCTs) in which either fish oil supplementation or isocaloric fish meal feeding was examined to determine the effect of long-chain ω-3 polyunsaturated fatty acid (ω-3 PUFA) consumption on circulating adiponectin.

The researchers found that, of the 14 RCTs included in the analysis, 14 had trial arms evaluating fish oil (fish oil, 682 participants; placebo, 641 participants). Fish oil significantly increased adiponectin by 0.37 µg/mL. Statistical heterogeneity was evident (I² = 72.9 percent) even though effects in 12 of 14 trials were ≥0 and were unexplained by ω-3 PUFA dose or duration, study quality score, study location, or baseline body mass index. Smaller trials with greater effects were identified by asymmetrical funnel plots. There was a theoretical pooled effect of 0.18 µg/mL suggested with the fill-and-trim method (P = 0.28). Fish feeding was evaluated in only two trial arms (136 intervention and 68 control subjects), with the pooled effect on adiponectin not reaching statistical significance.

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“These findings provide no evidence for harm and support possible benefits of ω-3 PUFA consumption on insulin sensitivity and adipocyte function,” the authors write.

One author disclosed financial ties to the food and pharmaceutical industries.