"While prior animal studies found fish oil increased circulating adiponectin, similar effects in humans was not established," lead author Jason Wu of the Harvard School of Public Health said in a statement. "By reviewing evidence from existing randomized clinical trials, we found fish oil supplementation caused modest increases in adiponectin in the blood of humans."
The meta-analysis reviewed and analyzed results from 14 randomized, placebo-controlled clinical trials involving 682 subjects treated with fish oil, and 641 given placebos -- most commonly olive and sunflower oils.
In those taking fish oil, adiponectin levels increased by 0.37 microgram per milliliter.
The results also suggested the effect of fish oil on adiponectin differed substantially across the trials, suggesting that fish oil supplementation might have stronger influence on adiponectin in some populations and weaker effects in others, Wu said.
"Although higher levels of adiponectin in the bloodstream have been linked to lower risk of type 2 diabetes and coronary heart disease, whether fish oil influences glucose metabolism and development of type 2 diabetes remains unclear," Wu said. "However, results from our study suggested higher intake of fish oil might moderately increase blood level of adiponectin, and these results support potential benefits of fish oil consumption on glucose control and fat cell metabolism."
The study was published in the journal Clinical Endocrinology & Metabolism.