Fish oil supplements, also called omega 3 fatty acid capsules, raise levels of adiponectin in the bloodstream.
Adiponectin is an important hormone that has beneficial effects on metabolic processes like glucose regulation and the modulation of inflammation.
In long-term human studies, higher levels of adiponectin are associated with lower risks of type 2 diabetes and coronary heart disease.
"While prior animal studies found fish oil increased circulating adiponectin, whether similar effects apply in humans is not established," said the study's lead author, Jason Wu, of the Harvard School of Public Health.
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The meta-analysis reviewed and analysed results from 14 randomised, placebo-controlled clinical trials.
In total, 682 subjects were treated with fish oil, and 641 were given placebos - most commonly olive and sunflower oils.
In those taking fish oil, adiponectin levels increased by 0.37 microgrammes per millilitre.
The results also found the effect of fish oil on adiponectin differed substantially across the trials, suggesting that fish oil supplementation may have stronger influence on adiponectin in some populations and weaker effects in others.
"Although higher levels of adiponectin in the bloodstream have been linked to lower risk of diabetes and coronary heart disease, whether fish oil influences glucose metabolism and development of type 2 diabetes remains unclear," said Wu.
"However, results from our study suggest that higher intake of fish oil may moderately increase blood level of adiponectin, and these results support potential benefits of fish oil consumption on glucose control and fat cell metabolism," Wu added.
The study will be published in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism (JCEM).