Abstract
Green tea catechin ingestion or gargling exhibit anti-viral activity against upper respiratory infection. We hypothesized that retention in the oral cavity could improve the anti-viral effects of catechins. The present study investigated the oral retention of catechins in humans and the effect of catechin beverage viscosity on oral retention. Two intervention studies with different test beverages, beverage-C (40 mL, containing 73.4 mg of catechins) and beverage-XT (40 mL, beverage-C containing 100 mg xanthan gum) were conducted in 20 healthy volunteers (mean age 38.7 years). Catechin concentrations were measured in buccal mucosa samples collected at 10 min, 40 min, and 60 min after ingesting test beverages, and the catechin variability of the tissue after intake was compared between test beverages. As a result, the mean (SEM) concentrations of EGCG were 99.9 (27.2), 58.2 (16.6), and 22.3 (5.7) ng/mg-mucosa at 10, 40, and 60 min, respectively, after ingestion of beverage-XT. Similarly, the catechin concentrations were 86.1 (20.3), 32.2 (5.3), and 27.8 (5.9) ng/mg-mucosa after ingestion of beverage-C. The total retention volume over 60 min tended to be slightly higher after ingestion of beverage-XT, though the difference was not statistically significant. Additional studies are needed to confirm the effect of xanthan gum on improving oral retention of catechins.
Highlights
Green tea, produced from the leaves of Camellia sinensis (L.) exhibits anti-tumor, antiinflammatory, anti-microbial, and anti-viral activities, thereby conferring many health benefits to humans [1,2]
Various biological and pharmacological studies have revealed that the mechanisms of the anti-viral activity of EGCG against the influenza virus occurs via the inactivation of the viral envelope proteins or cellular receptors, or damage to the viral membrane, thereby blocking viral penetration into cell [5,6,7,8,9]
The present study explored the retention of tea catechins in the human oral cavity, and investigated the effect of a high beverage viscosity on the retention of catechins in the oral cavity
Summary
Green tea, produced from the leaves of Camellia sinensis (L.) exhibits anti-tumor, antiinflammatory, anti-microbial, and anti-viral activities, thereby conferring many health benefits to humans [1,2]. The catechins in green tea leaves include many types of polyphenols, they contain especially high concentrations of epigallocatechin-3gallate (EGCG), epicatechin 3-gallate (ECG), epigallocatechin (EGC), and epicatechin (EC). Studies of tea catechin gargling (the movement of a liquid around in throat and oral cavity without swallowing) indicate a tendency toward a reduction in the incidence of influenza, but the results are neither statistically significant nor established with sufficient clinical evidence [14,15,16]. It is important to clarify how long catechins are retained in the oral cavity after ingesting tea catechins, and whether retention in the oral cavity is a mechanism underlying the effects for controlling influenza infection in humans. The present study explored the retention of tea catechins in the human oral cavity, and investigated the effect of a high beverage viscosity on the retention of catechins in the oral cavity
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