Indian Tea Association:Research Files

The antitumour effect of tea has been evaluated in 3-methylcholanthrene (3-MC) induced solid tumour model in mice. Tea inhibited tumour growth and prevented metastasis. Histopathological study showed that tea treatment was able to reduce malignancy. Superoxide dismutase (SOD) , a free radical scavenger , was found to be significantly increased in serum of tea administrated mice. Moreover , tea extracts were able to reduce the level of thiobarbituric acid reactive substance (TBARS) in sera of mice.

Tea extract (both black and green) also showed anti-inflammatory activity in carrageenan-induced paw oedema model in rat. Our recent study showed inhibition of leukemic cell growth , isolated from cancer patient , using tissue culture system . The study reveals that , like green tea , black tea also possesses antineoplastic activity. The antineoplastic activity of Tea Root Extract (TRE) and its saponins has also been indicated using human leukemic cell.

Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study Antioxidant flavonols and ischemic heart disease in a Welsh population of men: the Caerphilly Study Michaël Hertog, peter M Sweetnam, Ann M Fehily, Peter C Elwood and Daan Kromhout. Am J Clin Nutr 1997; 65:1489-94

Antioxidant flavonols and their major food source, black tea, have been associated with a lower risk of ischemic heart disease (IHD) and stroke in Welsh men. We investigated whether flavonol intake predicted a lower rate of IHD in 1900 Welsh men aged 45-59 y, who were followed up for 14y. Flavonol intake, mainly from tea to which milk is customarily added, was not related to IHD incidence [relative risk (RR), highest compared with lowest quartile: 1.0;95% CI:0.6, 1.6;P for trend = 0.996; n - 186] but was weakly positively related to IHD mortality (RR:1.4;95% CI: 1.0, 2.0; P - 0.014; n = 334). Men with the highest consumption of tea (>1.2L, or <2 cups/d). We conclude that intake of antioxidant flavonols is not inversely associated with IHD risk in the United Kingdom. Possibly, flavonols from tea to which milk is added are not absorbed; experimental evidence suggests that adding milk to tea abolishes the plasma antioxidant-raising capacity of tea. The apparent association between tea consumption and increased mortality in this population merits further investigation.

For further information on Tea and Health, contact: The Tea Council, Sir John Lyon House, 5 High Timber Street, London, EC4V 3NJ Tel: +44 171 248 1024, Fax: +44 171 329 4568, e-mail: visitor@teahealth.co.uk

Pretreatment of hot water extract of black tea (BTE) (10% W/V) for & days at a dose of 20 ml/kg body weight through intragastric administration has been shown to significantly reduce the incidence of ulcer, ulcer number and ulcer index produced by known ulcerogenic agents like aspirin, indomethacin, ethanol, reserpine and cold restraint stress in rats as an experimental model. The ability of BTE pretreatment to protect acute ulceration by known ulcerogens was further assessed to get some insight into the mechanism(s) of antiulcer activity of BTE. Glutathione is known to have a major role in protecting gastric mucosa. The levels of glutathione and glutathione peroxidase were significantly decreased by administration of ulcerogenic agents like ethanol, diethyl dithiocarbonate (DDC) and diethyl maleate (DEM). This decrease in glutathione and glutathione peroxidase was effectively prevented by BTE pretreatment in the aforesaid manner. Other major features of BTE-induced reversal of ulcerogenic agents include a significant decrease in the protein content and a marked increase in hexosamine and sialic acid content in gastric juice which represent an indication of protection against mucosal injury. All these results suggest a major role for glutathione, an endogenous antioxidant, in the cytoprotection against ulcertion afforded by black tea extract.

Both black and green tea extracts
were found to possess preventive
as well as curative effects on experimentally
produced diabetes in rats.

Black tea extract was also found to possess
antidiarrhoeal property

The effect of hot water extracts of both black tea and green tea on streptozotocin-induced diabetes in rats and of hot water extract of black tea on five rodent models of diarrhoea were investigated . Both black and green tea extracts were found to possess preventive as well as curative effects on experimentally produced diabetes in rats. Black tea extract was also found to possess antidiarrhoeal activity in all the five rodent models of diarrhoea used. The study reveals that, like green tea , black tea also possesses antidiabetic activity. The observation of anti-diarrhoeal activity of black tea extract supports the use of black tea liquor in the treatment of diarrhoea.

Prokinetic Effect of Black Tea On Gastrointestinal Motility L.Chaudhuri and D.K. Ganguly Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Roan, Calcutta 700 032, India

The gastrokinetic effects of hot water extract of black tea on gastrointestinal motility were studied. Both in vivo and in vitro. The extract significantly accelerated the gastrointestinal transit (GIT) in vivo in mice. These facilitatory effect was reduced after pretreatment with atropine, hemicholinium-3 , morphine, indomethacin, McN- A-343 and L-arginine. In guinea pig ileum, the extract facilitated the peristaltic reflex in response to pressures in normal preparation. The black tea extract markedly enhanced the tonic("hump") responses to transmural stimulation in longitudinal muscle of guinea pig ileum which was unaltered in the presence of atropine. These findings suggest a cholinergic involvement and a partial role of protaglandin and nitric oxide in the mechanism of action of black tea extract on gastrointestinal motility. To unearth the effective constituents in black tea responsible for this activity, the effect of black tea polyphenols on GIT were also studied. Thearubigin fraction (but not theaflavin) accelerated GIT significantly which suggests its involvement in the prokinetic effect of black tea.

Antimutagenic effects of black tea (world blend tea) in Salmonella strains TA97a , TA98 , TA100 and TA102 both with and without metabolic activation Ashok K.Giri , Sutopa Gupta , Pallab Seth and Dilip K.Ganguly Indian Institute of Chemical Biology , 4 , Raja S.C. Mullick Road , Jadavpur , Calcutta - 700 032 , India

Antimutagenic effects of black tea (world blend tea) in Salmonella strains TA97a , TA98 , TA100 and TA102 were carried out in both plate incorporation and preincubation tests in both with and without S9 activation. In the mutitagenicity assay world blend tea did not show any mutagenic effects in any of the tester strains used in this assay . Antimutagenic effects were carried out in the bacterial plates treated with different concentrations (1, 2.5 , 5 , 10 and 20%) of tea extracts with known bacterial mutagens. In the antimutagenicity assays in plate incorporation test a significent decrease in revertant colonies were observed in plates treated with 1 to 20 % of tea extract plus positive mutagens when compared with only positive mutagens treated plates in both with and without S9 activation in these strains. The protective effects were little more when S9 was added to it. The protective effects were 10 to 31 % in plate incorporation test without S9 and were 10 to 42 % with S9 activation. In the preincubation test the protective effects were 10 to 57 % in without S9 activation and 10 to 54 % with S9 activation. In this preincubation test there were no significant differences between the with or without S9 activation. The overall results indicate that world blend tea has a significant protective effects against known bacterial mutagens in Ames Salmonella assay.