Background　In Japan, 10-20％ of people are troubled with tinnitus. Although its mechanism is not elucidated, it is suggested that blood flow and temperature around ear auricle relate to tinnitus. Oligonol^®, a low molecular weight polyphenol from lychee fruit, is known to have the various physiological functions such as elevation of body temperature by improving blood flow. Thus, the ameliorative effect of Oligonol^® on tinnitus was investigated.
Methods　A randomized, double-blind, placebo-controlled exploratory study in healthy subjects with mild tinnitus was conducted. The subjects took 100 mg/day of either Oligonol^® or placebo once a day for four weeks. Tinnitus Handicap Inventory（THI）, Visual Analog Scale （VAS）including tinnitus symptom and quality of life（QOL）, and eardrum temperature were evaluated.
Results　The VAS score for“coldness on the hands and feet”in the Oligonol^® group was significantly improved compared to the placebo group. Additionally, the VAS score for“frequency of asking what has been said”in the Oligonol^® group showed a tendency to improve compared to the placebo group. Furthermore, the VAS scores for "influence on sleep by ear noise”, "dizziness” and“coldness on the hands and feet”in the Oligonol^® group were significantly improved after four weeks compared to the initial. The eardrum temperature was significantly decreased in the placebo group while the Oligonol^® group showed no significant change in the eardrum temperature.
Conclusion　These results suggest that Oligonol^® improves the condition of tinnitus and consequently enhances QOL.