The Effect of Tea Catechins on Natural Killer Cell Activity in the Elderly: A Pilot Study

Iketani, Ryo; Furushima, Daisuke; Nishimura, Takuma; Hirama, Yui; Onishi, Shintaro; Kanbara, Hidetoshi; Mori, Takuya; Ota, Noriyasu; Ohno, Yuko; Yamada, Hiroshi

doi:10.3999/jscpt.50.139

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…Bottled beverages contain epi-type and non-epi-type catechins (Table 1), whereas powders and capsules primarily contain epi-type catechins [6,7]. Catechin consumption has been previously shown to significantly enhance NK cell activity in humans at approximately the same isomerization rate and quantity and concentration of catechins as those used in the present study [18]. Furthermore, the powder or capsular form that primarily contains epi-type catechins increases NK cell cytolysis in animal studies [19].…”

Section: Discussionmentioning

confidence: 58%

Effect of Catechins on Upper Respiratory Tract Infections in Winter: A Randomized, Placebo-Controlled, Double-Blinded Trial

et al. 2022

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Tea catechins are plant-derived compounds that improve immune functions. Previous randomized control trials have demonstrated the efficacy of primarily epi-type catechins against upper respiratory tract infections (URTIs). Green tea can be consumed in several ways, including popular bottled beverages. These beverages, however, require sterilization during manufacturing, which results in catechin isomerization. We conducted a randomized, double-blinded, placebo-controlled trial involving healthy Japanese participants to evaluate whether catechin consumption via bottled beverages has an alleviating effect on the duration and severity of URTIs in winter. The catechin group (490 mg catechin, 0.14%, containing 59% epi-type catechin, n = 55) showed reduced durations of running nose, nasal congestion, and headache, compared with the placebo group (0 mg catechin, n = 54; p = 0.013, 0.018, and <0.001, respectively). Furthermore, when considering physical symptoms, the duration of nasopharyngeal symptoms improved significantly in the catechin group (p < 0.001) compared with that in the control group. The daily consumption of catechin thus reduced the duration and severity of URTIs in healthy men and women. Humans are regularly exposed to several potential infectious threats, and the oral administration of heat-epimerized tea catechins might help prevent and reduce the severity of URTIs.

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Section: Discussionmentioning

confidence: 58%

Effect of Catechins on Upper Respiratory Tract Infections in Winter: A Randomized, Placebo-Controlled, Double-Blinded Trial

et al. 2022

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“…Peripheral blood mononuclear cells (PBMCs) were isolated by density gradient centrifugation using Isolymph (CTL Scientific Supply Co.) and the natural killer (NK) cell activity of the PBMCs was determined using the chromium-51 ( 51 Cr) release method 44 , Supplementary Methods).…”

Section: Methodsmentioning

confidence: 99%

Lactic acid as a major contributor to hand surface infection barrier and its association with morbidity to infectious disease

Nishioka

Nagano

Koga

et al. 2021

Sci Rep

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Although the surface of the human hands contains high antimicrobial activity, studies investigating the precise components involved and the relationship between natural antimicrobial activity and morbidity in infectious diseases are limited. In this study, we developed a method to quantitatively measure the antimicrobial activity of hand surface components. Using a clinical survey, we validated the feasibility of our method and identified antimicrobial factors on the surface of the human hand. In a retrospective observational study, we compared the medical histories of the participants to assess infectious diseases. We found that the antimicrobial activity on the surface of the hands was significantly lower in the high morbidity group (N = 55) than in the low morbidity group (N = 54), indicating a positive association with the history of infection in individuals. A comprehensive analysis of the hand surface components indicated that organic acids, especially lactic acid and antimicrobial peptides, are highly correlated with antimicrobial activity. Moreover, the application of lactic acid using the amount present on the surface of the hand significantly improved the antimicrobial activity. These findings suggest that hand hygiene must be improved to enhance natural antimicrobial activity on the surface of the hands.

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“…Peripheral blood molecular cells (PBMCs) were isolated by density gradient centrifugation using Isolymph (CTL Scientific Supply Co.), according to the manufacturer’s instructions. The natural killer (NK) cell activity of the PBMCs was determined using the chromium-51 ( 51 Cr) release method, as previously described [11]. Briefly, PBMCs isolated as effector cells and K-562 tumor cells labeled with 51 Cr as target cells were incubated at a ratio of 1:50 for 4 h at 37°C.…”

Section: Methodsmentioning

confidence: 99%

Detailed Analysis of Surface Infection Barrier on Hands: Relationship with Morbidity to Infection Diseases and Identification of Antimicrobial Components

Nishioka¹,

Nagano

Koga

et al. 2020

Preprint

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Although the surface of hands in humans is known to harbor high levels of antimicrobial activity, reports investigating the relationship between antimicrobial activity and morbidity in infectious diseases are lacking. Additionally, the precise components involved in this activity are not known. Therefore, in this study, a method was developed to quantitatively measure the antimicrobial activity of the components found on the surface of hands, which was then compared with the medical history of the participants for infectious diseases. As a result, the antimicrobial activity of the surface of the hands was found to be positively associated with the history of infection in individuals. Furthermore, a comprehensive analysis of the components on the surface of hands indicated that organic acids and antimicrobial peptides are highly correlated with antimicrobial activity. The high amounts of lactic acid found on the surface of hands suggested it is an important factor in the hand surface infection barrier. Here we showed that the application of lactic acid within the range of the amounts present on the hand surface was found to significantly improve the antimicrobial activity of the hands. Taken together, these results demonstrate that this new method can be used to quantify antimicrobial activity, which opens new avenues for the development of hand hygiene practices by enhancing the antimicrobial activity on the surface of hands using natural ingredients against pathogens.

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The Effect of Tea Catechins on Natural Killer Cell Activity in the Elderly: A Pilot Study

Cited by 4 publications

References 27 publications

Effect of Catechins on Upper Respiratory Tract Infections in Winter: A Randomized, Placebo-Controlled, Double-Blinded Trial

Effect of Catechins on Upper Respiratory Tract Infections in Winter: A Randomized, Placebo-Controlled, Double-Blinded Trial

Lactic acid as a major contributor to hand surface infection barrier and its association with morbidity to infectious disease

Detailed Analysis of Surface Infection Barrier on Hands: Relationship with Morbidity to Infection Diseases and Identification of Antimicrobial Components

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