The research, published in Journal of Functional Food, suggests intake of highly bioavailable polyphenols – in the form of the branded ingredient Oligonol, extracted from lychee fruit – may reduce the risk of developing hyperinsulinemia (excess levels of circulating insulin) and gout by blocking the production of excess uric acid.
“The inhibitory effect of Oligonol on xanthine oxidase activity suggests that this new phenolic substance may be a beneficial supplement for individuals with mild hyperuricemia and at risk for gout,” said the researchers, led by Yuji Moriwaki from the Hyogo College of Medicine, Japan.
The ingredient was supplied by Japan’s Amino Up Chemical Co, Ltd., and researchers from the company also participated in the study.
Gout is a painful form of arthritis caused by disturbances in uric acid metabolism, when an overload of uric acid leads to the formation of urate crystals in bodily tissues, especially the joints – leading to recurring attacks of joint inflammation.
Hyperinsulinemia and insulin resistance can lead to increased uric acid re-absorption in the kidneys, which in turn can lead to a rise in serum uric acid concentration.
Polyphenols are a large family of natural compounds widely distributed in plant foods. They have been suggested to improve insulin sensitivity in animal models and human studies, and according to the authors, may also decrease the concentration of uric acid in serum.
Polyphenols have been shown to possess anti-inflammatory, anti-microbial, anti-carcinogenic, and antioxidant properties, however Moriwaki and co workers noted that there are no known studies assessing the effects of polyphenols on uric acid metabolism in vivo.
The new study investigated changes in serum concentration and urinary excretion of uric acid following intake of Oligonol, a novel a phenolic substance produced from lychee fruit polyphenols, which is reported to have a higher bioavailability than ordinary polyphenols.
Oligonol was reported to significantly decrease uric acid excretion over the course of one hour. The researchers observed the reduction in uric acid excretion was accompanied by a decreased serum concentration of uric acid.
In addition, they said in vitro experiments showed that polyphenol supplementation inhibited the activity of xanthine oxidase, an enzyme that catalyzes the oxidation of xanthine to uric acid, in a dose-dependent manner.
“Together, these results suggest that Oligonol lowers serum uric acid through inhibition of xanthine oxidase, and may be effective for prevention and treatment of hyperuricemia and/or gout,” said Moriwaki and colleagues.
The Japanese researchers added that although Oligonol decreases serum concentration of uric acid through inhibition of uric acid production, the mechanism behind Oligonol-induced decreases in fractional uric acid clearance remains undetermined
“It will be important to determine whether long-term ingestion of Oligonol could be useful to treat hyperuricemia or prevent gout development,” they concluded.
Source: Journal of Functional Food
Published online ahead of print, doi: 10.1016/j.jff.2010.11.002
“Effects of Oligonol, an oligomerized polyphenol formulated from lychee fruit, on serum concentration and urinary excretion of uric acid”
Authors: Y. Moriwaki, C. Okuda, A. Yamamoto, T. Ka, Z. Tsutsumi, S. Takahashi, T. Yamamoto, K. Kitadate, K. Wakame