Carcinogenicity of Camellia sinensis (Tea) and Some Tannin-Containing Folk Medicinal Herbs Administered Subcutaneously in Rats23

Kapadia, Govind J.; Paul, BR; Chung, E. B.; Ghosh, B. N.; Pradhan, Surbhi

doi:10.1093/jnci/57.1.207

Cited by 59 publications

(17 citation statements)

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“…A partial explanation may be the inadequacy of the standardisation procedure. For In view of the fact that tea is mutagenic by the Ames test (Nagao et al, 1979) and contains tannins that are carcinogenic in animals (Korpassi & Mosonyi, 1950;Kapadia et al, 1976) it must be conceded that the relationships found in this study with stomach and lung cancers might be causal. Given that the stomach but not the lung is directly exposed to tea as drunk, the similarity of the relative risks shown by stomach and lung cancers makes an indirect relationship seem more probable.…”

Section: Discussionmentioning

confidence: 88%

Tea consumption and cancer

Kinlen

Willows²,

Goldblatt³

et al. 1988

Br J Cancer

138

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Summary Following the report from Hawaii (Heilbrun et al., 1986) of relationships between tea consumption and respectively rectal cancer (positive) and prostate cancer (negative), these questions were examined using data from a prospective mortality study of London men initiated in 1967. The small numbers of men who did not usually drink any tea prevented a reliable study of this sub group. Nevertheless no evidence of a dose-response relationship was found for rectal, colon or prostate cancer. Significant relationships were found, however, between tea consumption and deaths from stomach, lung and kidney cancers. In the case of stomach and lung cancer, these were partly due to the effects of social class and smoking, and possible reasons are considered for the residual relations.A prospective study of men of Japanese ancestry in Hawaii reported that, compared with those who seldom or never drank black tea, habitual drinkers showed an increased incidence of rectal cancer, and that there was a doseresponse relationship (Heilbrun et al., 1986). ('Black tea' is the commonest type of tea and that which is mainly drunk in Britain). In addition, prostate cancer showed a weaker, negative association with tea consumption. This has prompted us to investigate the mortality from rectal and other cancers in relation to tea consumption, using data from a prospective study initiated by one of us (JY) in 1967. MethodsA random sample of about 20,000 men aged 45-60 in London was sent questionnaires about diet (including consumption of tea, coffee and other beverages) and smoking habits, by the General Register Office in December 1967. Respondents were 'flagged' in the NHS Central Register so that deaths, and their causes, could be identified as they occurred. Details of causes of death were coded by the Office of Population Censuses and Surveys (OPCS). These details, together with those on diet, were provided by OPCS without disclosure of identities.The questionnaire asked for the average consumption of tea and other beverages before breakfast, at breakfast, midmorning break, midday, tea-time, evening, bed-time, or at any other time. Man-years at risk were calculated by tea consumption category from the end of June 1969 to the end of 1986, or to death or emigration if earlier. Expected numbers of deaths from different causes were calculated by multiplying the age-specific mortality rates for men in England and Wales in the different calendar periods by the corresponding man-years at risk.Statistical modelling of the data was carried out using the computer package GLIM (Baker & Nelder, 1978). For this purpose it was assumed that observed deaths are Poisson variables with means proportional to the corresponding expected numbers (Breslow et al., 1983).Of the approximately 20,000 questionnaires that were sent, replies were received from 14,453 men, and of these the 14,085 (97%) who were traced in the NHS Central Register form the study population.By the end of 1986, a total of 5,732 deaths had been recorded in the study population. An...

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Section: Discussionmentioning

confidence: 88%

Tea consumption and cancer

Kinlen

Willows²,

Goldblatt³

et al. 1988

Br J Cancer

138

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“…Rats drinking 2% green tea for life showed decreased incidence of lung carcinoma induced by Crocidolite plus BP, as well as delayed onset of carcinoma and increased mean survival time of rats with carcinoma [61]. Repeated, subcutaneous injection of black tea tannin given to NIH black rats resulted in tumor formation at the injection site; however, this effect was not observed in rats treated with the total aqueous extract from black tea [62,63].…”

Section: Animal Modelsmentioning

confidence: 96%

Chemoprevention of lung cancer by tea

Clark

You²

2006

Molecular Nutrition Food Res

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Tea is the second only to water as the most consumed beverage in the world. Both green and black teas have been studied for their health benefits for a variety of diseases, particularly cancer. Lung cancer is the predominant cause of cancer mortality in developed countries. Smokers' risk of lung cancer is 20 times that of persons who have never smoked. Epidemiological studies on the cancer-preventive effects of tea produce inconsistent results, which could in part be attributed to the lack of a universal standard for tea preparations. However, most animal studies indicate that tea has strong chemopreventive effects against lung tumorigenesis. The reported mechanisms for chemopreventive activity of green tea are antioxidation, induction of phase II enzymes, inhibition of TNFalpha expression and release, inhibition of cell proliferation, and induction of apoptosis. Cell cycle arrest and apoptosis induced by green tea are probably the two most significant factors. Future studies are needed to determine how green tea affects the genes associated with cell cycle regulation and apoptosis during the mouse lung carcinogenesis process.

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“…Heilbrun. Received 2 January 1986; and in revised form 26 June 1986. injection site in rats (Kapadia et al, 1976). These animal studies have generally used high doses.…”

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confidence: 99%