Efficacy of fermented green tea on peripheral skin temperature: a randomized and placebo-controlled clinical study

Summary Background This study was aimed at assessing the therapeutic efficacy of green tea on peripheral skin for cold hypersensitive subjects, who had the feeling of cold hands and feet at cold temperatures, one of the most common complaints in Asian women. Methods This randomized and placebo‐controlled clinical study included 60 female Korean subjects who had the feeling of cold hands and feet at cold temperatures. The subjects were randomly assigned into two groups to receive fermented green tea or a placebo (hot water). Results The skin temperature of the hands and feet was measured using digital infrared thermography at the baseline and at 15, 30, 45, and 60 min after the oral administration of the tea or placebo. The skin temperature of the hands and feet of the fermented green tea‐administered group was significantly higher than that of the placebo‐administered group. The temperature difference between the finger and the dorsum of the hand was significantly lower in the fermented green tea‐administered group than that in the placebo group. Conclusions Fermented green tea is helpful for cold hypersensitivity. This is the first clinical study to evaluate the efficacy of fermented green tea on peripheral skin in subjects having the feeling of cold hands and feet at cold temperatures by infrared thermography. However, further studies are necessary to evaluate the long‐term effects of the fermented green tea for cold hypersensitivity and to elucidate the underlying physiological mechanism.