cancer-prevention

Author: Etsuji Suzuki and Takashi Yorifuji and Soshi Takao and Hirokazu Komatsu and Masumi Sugiyama and Toshiki Ohta and Kazuko Ishikawa-Takata and Hiroyuki Doi

Purpose To investigate the association between green tea consumption and mortality from all causes, cancer, and cardiovascular disease (CVD) among elderly people. Methods In a population-based, prospective cohort study, a total of 14,001 elderly residents (aged 65–84 years), randomly chosen from all 74 municipalities in Shizuoka, Japan, completed questionnaires that included items about frequency of green tea consumption. They were followed for up to 6 years, from December 1999 to March 2006. Consequently, 12,251 subjects were analyzed to estimate the hazard ratios (HRs) for all-cause mortality, cancer, and CVD. Results Among 64,002 person-years, 1,224 deaths were identified (follow-up rate, 71.6%). The multivariate HRs and 95% confidence intervals (CIs) for CVD mortality compared those who consumed seven or more cups per day with those who consumed less than one cup per day, were 0.24 (0.14–0.40), 0.30 (0.15–0.61), and 0.18 (0.08–0.40) for total participants, men, and women, respectively. Although green tea consumption was not inversely associated with cancer mortality, green tea consumption and colorectal cancer mortality were inversely associated with a moderate dose-response relationship. Conclusions Green tea consumption is associated with reduced mortality from all causes and CVD. This study also suggests that green tea could have protective effects against colorectal cancer.

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Author: Chwan-Li Shen and James K. Yeh and Jay J. Cao and Jia-Sheng Wang

Osteoporosis is a major health problem in both elderly women and men. Epidemiological evidence has shown an association between tea consumption and the prevention of age-related bone loss in elderly women and men. Ingestion of green tea and green tea bioactive compounds may be beneficial in mitigating bone loss of this population and decreasing their risk of osteoporotic fractures. This review describes the effect of green tea or its bioactive components on bone health, with an emphasis on (i) the prevalence and etiology of osteoporosis; (ii) the role of oxidative stress and antioxidants in osteoporosis; (iii) green tea composition and bioavailability; (iv) the effects of green tea and its active components on osteogenesis, osteoblastogenesis, and osteoclastogenesis from human epidemiological, animal, as well as cell culture studies; (v) possible mechanisms explaining the osteoprotective effects of green tea bioactive compounds; (vi) other bioactive components in tea that benefit bone health; and (vii) a summary and future direction of green tea and bone health research and the translational aspects. In general, tea and its bioactive components might decrease the risk of fracture by improving bone mineral density and supporting osteoblastic activities while suppressing osteoclastic activities.

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Author: Antonios E. Koutelidakis and Mauro Serafini and Michael Komaitis and Maria Kapsokefalou

We tested in mice the hypothesis that iron fortificants may exert oxidative activity on colon tissue homogenates (CTH), depending on the antioxidant capacity of infusions received with their diet. CTH were obtained from mice receiving daily by gavage 0.1 mL of infusion (8 g/100 mL water) from green tea or white tea or Pelargonium purpureum or catechin (0.01 g/100 mL) or water (control) for five days. All CTH had higher total antioxidant capacity than the control and lower susceptibility to oxidation induced by the retentates of in vitro digests of ferrous lactate, ferrous gluconate, ferrous sulfate and NaFeEDTA. Ferrous sulfate and NaFeEDTA exhibited higher oxidative effect on CTH than ferrous gluconate or ferrous lactate. These results are in support of our hypothesis and suggest that infusions received with diet may protect the colon from a potential oxidative effect of non-absorbed iron.

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Author: Gang Xu and Guijie Ren and Xia Xu and Huiqing Yuan and Zhenzheng Wang and Ludong Kang and Wenguang Yu and Keli Tian

Author: Keon Wook Kang and Soo Jin Oh and Shi Yong Ryu and Gyu Yong Song and Bong-Hee Kim and Jong Seong Kang and Sang Kyum Kim

The antioxidant activity of catechins isolated from green tea against peroxyl radicals, hydroxyl radicals, and peroxynitrite was determined using the total oxy-radical scavenging capacity (TOSC) assay. (−)-Epicatechin, (−)-epigallocatechin, (−)-epicatechin-3-gallate, and (−)-epigallocatechin-3-gallate were isolated and their structures were characterised based on their physical and spectral properties, and by comparison of these results with similar data in the literature. (−)-Epigallocatechin showed the highest TOSC value, and (−)-epicatechin-3-gallate was the least effective among the catechins tested. These results indicated that the presence of a gallate group at the three position plays a critical role in their antioxidant activity. However, additional insertion of a hydroxyl group at the 5′ position in the B ring attenuates the oxy-radical scavenging capacity of catechins. These results suggest that the antioxidant activity of catechins is dependent on the reactivity of both the original catechins and their products generated during reaction with oxy-radicals.

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Author: Norleena P. Gullett and A.R.M. Ruhul Amin and Soley Bayraktar and John M. Pezzuto and Dong M. Shin and Fadlo R. Khuri and Bharat B. Aggarwal and Young-Joon Surh and Omer Kucuk

Botanical and nutritional compounds have been used for the treatment of cancer throughout history. These compounds also may be useful in the prevention of cancer. Population studies suggest that a reduced risk of cancer is associated with high consumption of vegetables and fruits. Thus, the cancer chemopreventive potential of naturally occurring phytochemicals is of great interest. There are numerous reports of cancer chemopreventive activity of dietary botanicals, including cruciferous vegetables such as cabbage and broccoli, Allium vegetables such as garlic and onion, green tea, Citrus fruits, soybeans, tomatoes, berries, and ginger, as well as medicinal plants. Several lead compounds, such as genistein (from soybeans), lycopene (from tomatoes), brassinin (from cruciferous vegetables), sulforaphane (from asparagus), indole-3-carbinol (from broccoli), and resveratrol (from grapes and peanuts) are in preclinical or clinical trials for cancer chemoprevention. Phytochemicals have great potential in cancer prevention because of their safety, low cost, and oral bioavailability. In this review, we discuss potential natural cancer preventive compounds and their mechanisms of action.

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Author: Zerrin Yuksel and Elif Avci and Yasar Kemal Erdem

Author: Ubonrat Siripatrawan and Bruce R. Harte

An active film from chitosan incorporated with aqueous green tea extract (GTE) was developed. The effects of GTE concentrations including 2, 5, 10 and 20% (w/v) of green tea in the film-forming solution on the film properties were determined by measuring physical properties, total polyphenolic content and antioxidant activity of the active films. Fourier Transform Infrared (FTIR) spectrometry was carried out to observe the potential modifications of the chitosan films when incorporated with GTE. The results suggested that incorporation of GTE into chitosan films improved mechanical and water vapor barrier properties and enhanced polyphenolic content and antioxidant activity of the films. Changes in the FTIR spectra of the chitosan films were observed when GTE was incorporated, suggesting some interactions occurred between chitosan and the polyphenols from GTE. This study showed the benefits of incorporation of GTE into chitosan films and the potential for using the developed film as an active packaging.

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Author: Masoumeh Akhlaghi and Brian Bandy

Green tea catechins are dietary antioxidant compounds that have been shown to protect against myocardial ischemia-reperfusion (IR) injury. Considering reports that catechins can induce phase 2 enzymes in cultured cells and some organs, we hypothesized that part of the protection to heart against IR injury may involve elevation of phase 2 enzyme activities. Rats were fed for 10 days with either control diet (sham and control groups) or the diet mixed with 0.25% green tea extract. At the end of 10 days, hearts were excised and subjected to global ischemia for 20 min followed by reperfusion for 2 hours. The hearts were compared for indices of cell death, oxidative stress, and phase 2 enzyme activities. Hearts from the green tea group had a 65% to 85% decrease in markers of apoptosis, a tendency to higher total glutathione, and higher activities of the phase 2 enzymes glutamate cysteine ligase and quinone reductase. The results support a possible involvement of phase 2 enzymes in the protection by green tea catechins against myocardial IR injury.

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Author: Tsong-Ming Lu and Ching-Ching Lee and Jeng-Leun Mau and Sheng-Dun Lin

Green tea powder was used to substitute 0%, 10%, 20%, and 30% of wheat flour to make sponge cakes, called the control, GT10, GT20, and GT30, respectively. The viscosity and specific gravity in cake batter, and hardness, gumminess, chewiness, crumb a value, protein, total dietary fibre, ash, and various catechin content of baked cakes increased with increasing green tea levels whereas the volume, cohesiveness, adhesiveness, springiness, resilience, crust L, a, b and crumb L, b values of samples showed a reverse trend. No differences were found in all hedonic sensory results for control, GT10, and GT20 whereas GT30 were rated lower in all sensory results. Green tea cake contained a greater variety of catechins, and had good antioxidant activity, reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions. Overall, green tea cake could be developed as a food with more effective antioxidant properties.

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