Effects of Polyphenols from Water Chestnut (Trapa japonica) on Lipid Metabolism

Abstract

Abstract Water chestnut (Trapa japonica), a uniquely shaped floating plant with thorns, contains many peculiar polyphenols. These polyphenols have been shown to exhibit high antioxidant activity and suppress postprandial blood glucose level rise. In recent years, obesity and lipid metabolism disorders have become a worldwide problem. Therefore, with the aim of investigating the effects of water chestnut polyphenols on lipid metabolism, we conducted in vitro studies, animal experiments, and human clinical studies (randomized, double-blind, placebo-controlled, and parallel-group comparative studies). Water chestnut polyphenol exhibited lipase inhibitory activity and inhibited fat accumulation in 3T3-L1 cells. In contrast, animal experiments using mice revealed that triglycerides and free fatty acids in the blood plasma of the polyphenol-treated group were significantly lower than those in the control group. Human clinical studies showed that the consumption of water chestnut tea significantly reduced visceral fat area and abdominal circumference; however, no significant difference was observed from the results for the placebo group. These results suggest a possible preventive effect of water chestnut polyphenols on the development of metabolic syndrome. This study was registered with the UMIN Clinical Trial Registry (UMIN000038165, October 4, 2019).