Study of relationship between green tea and cancer

Study of relationship between green tea and cancer Studies conducted in China revealed that green tea users had an approximate 50% reduction in risk for both esophageal cancer and stomach cancer. 

Inhabitants of tea producing districts in Japan have a lower mortality from stomach cancer, possibly the result green tea consumption. 

In addition to a regular tea drinking, this population consumes green tea all types of products, including candy, gums, bread, shampoo, lotion, toothpaste, etc. 

Contrary to the preceding, however to recent studies found no association between green tea consumption and stomach or colon cancer. 

Green tea was linked to a reduced risk of oral cancer in northern Italian and a Chinese population, esophageal cancer in Chinese women, gastric cancer in Swedish adolescents, pancreatic cancer in residents of a retirement community in the United States, and colon cancer in retired male self defense official in Japan. 

Cohort studies suggest that there is a protective effect of green tea for colon, urinary bladder, stomach, pancreatic and esophageal cancer. 

In Japanese survey, an overall protection by green tea was observed, together with slowdown of the increase of cancer incidence with age. The effects were more pronounced when the tea consumption was more than 10 cups/day. 

In another Japanese study, consumption of 7 or more cups per day of green tea significantly decreased the risk of cancer of both the stomach and rectum (by 31% and 54% respectively) compared with non-users. 

Regular tea drinkers in China experienced a lower incidence of cancer of the colon, rectum, and pancreas compared with non drinkers of tea. 

A case control study from Poland reported a significant reduction in risk of pancreatic cancer with increasing lifetime tea consumption. 

Increased green tea consumption was closely associated with decreased axillary lymph node metastases among patients who were premenopausal with stage 1 and 11 breast cancer and overall decreased recurrence of stage 1 and 11 breast cancer. 

Study of relationship between green tea and cancer

Tea and skin cancer

Skin cancer is the most common malignancy in the United States, and the number of cases annually surpasses all other malignancies combined.

Skin cancer can be classified as basal cell carcinoma, squamous cell carcinoma, and melanoma, according to histological characteristics. The effect of tea polyphenols on Toll-like receptor 4 (TLR4) in melanoma cell lines has been reported. One cup of green tea contains up to 200 mg of EGCG, which has been shown to have chemopreventive/chemotherapeutic effects against several types of cancers.

Both green and black teas contain abundant amounts of polyphenolic antioxidants and it has been shown that theaflavins in black tea and catechins in green tea are equally effective antioxidants.

Study published in Cancer Biology & Therapy concluded that black tea is a better chemopreventive agent than green tea against skin tumorigenesis. (Cancer Biol Ther 2009; 8:1281-7)

Research published in European Journal of Cancer shows data from 767 non-Hispanic Whites under age 40 was evaluated to understand the effects of tea, coffee, and caffeine on the early-onset of basal cell carcinoma. Inverse relationship was found to be associated with combined regular consumption of caffeinated coffee plus hot tea with early-onset of basal cell carcinoma. There was 43% reduced risk of basal cell carcinoma in people consuming the highest category of caffeine from these sources as compared with non-consumers. (Eur. J. Cancer Prev. 2014, 23, 296–302)

Polyphenols are the major active compounds present in teas. The catechins are the major polyphenolic compounds in green tea, which include epigallocatechin-3-gallate (EGCG), epigallocatechin, epicatechin-3-gallate and epicatechin, gallocatechins and gallocatechin gallate. EGCG is the predominant and most studied catechin in green tea.
Tea and skin cancer

Drinking green tea reduce the risk of stomach cancer

Tea is the most widely consumed beverage in the world aside from water. Tea is generally consumed in the form of green (20%), oolong (2%), or black (78%) tea.

Tea, one of the most commonly consumed beverages in the world. Tea and the constituents of tea have been shown in pre-clinical and epidemiological studies to inhibit tumorigenesis and provide protective effects against stomach cancer.

In areas of Japan where the most tea is drunk, the rate of stomach cancer is the lowest. Stomach cancer is the fourth most common cancer and second leading cause of death from cancer throughout the world.

According to Japanese researchers, drinking five cups of green tea a day could help women reduce the risk of developing stomach cancer by 20 percent.
Drinking green tea reduce the risk of stomach cancer

 

Drinking tea inhibits cancer

Tea is a beverage made from the leaves of Camellia sinensis species of the Theaceae family. Tea has long been tied to a lower risk of stomach, colon and breast cancer, although the connection is not proven.

In June 1, 1994 Journal of The National Cancer Institute published the result of an epidemiological study indicating that drinking green tea reduced the risk of esophageal cancer in Chinese men and women by nearly 60 percent.

Now lab studies find that tea chemicals actually may stop cancer growth. Rutgers University researchers showed that a compound in black tea called TF-2 caused colorectal cancer cells to "commit suicide"; normal cells were unaffected.

Scientific research shows that regular tea drinking, especially green and white tea, inhibits colon, breast, prostate, lung, melanoma, ovarian and bladder cancer.

The phytochemicals in tea suppress signaling molecules needed for cancer cell reproduction and block enzymes needed for tumor invasion – inhibiting the cancer process.

Tea and its polyphenols induce certain enzymes, such as glucuronosyl transferase, that detoxify carcinogens. 

Green tea extract EGCG (Epigallocatechin-3-Gallate) has been shown to inhibit hormone sensitive cancers, such as breast and prostate cancer.

Of importance also is that tea decreases the growth of neoplastic cells, but not of normal cells.

It is also important to note that tea enhances apoptosis, a phenomenon of elimination do cancer cells.
Drinking tea inhibits cancer

Green tea and cancer

Many of the studies have shown an inverse association between green tea consumption and cancer incidence, although there are some inconsistencies in the findings.

Green tea is produced by lightly steaming the fresh-cut black tea leaf; to produce black tea, the leaves are oxidized.

During oxidation many of the polyphenol substances compounds with potent antioxidant and anticancer properties, are destroyed. Unlike black tea, green tea is very high in polyphenols.

The anticancer effects are the result of the green tea polyphenols blocking the formation of cancer-causing compounds as well as effectively detoxifying or trapping cancer-causing chemicals.

Consumption of green tea is associated with improved prognosis of patients with breasts cancer.

Green tea is widely consumed in Japan, which historically has had a low incidence of breasts cancer, but is also popular elsewhere.

When a study was done to identify the specific contribution of black tea and green tea to breast cancer risk, green tea drinkers showed a significant reduced risk of breast cancer, while black tea drinkers did not enjoy this benefit.

Green tea also provides a protective effect against both esophageal and oral cancer, according to the American National Cancer Institute.

A dual study by the Shanghai Cancer Institute and the US National Cancer Institute shows that drinking green tea once a week for six months means less risk for colorectal and pancreatic cancers, with benefits stronger for women.
Green tea and cancer

Tea and Cancer

Tea and Cancer
Most of the on cancer chemoprevention by tea has been conducted using green tea or its individual polyphenolic constituents.

Less work has been reported on black tea.

In animal studies, the polyphenolic fraction isolated from green tea. The water extract of green tea, or individual polyphenolic antioxidants present in green tea have afforded protection against chemically induced carcinogenesis in the lung, liver, esophagus, forestomach, duodenum, pancreas, colon, and breast.

The raises possibility that green tea consumption and its associated catechins may lower cancer risk in humans.

Studies have shown that green tea intake increases the excretion of a class of carcinogens known as heterocyclic arylamines formed during the cooking of meat, poultry and fish; this is expected to reduce DNA adduct formation, in particular and carcinogenesis, in general.

Consumption of both green and black tea aqueous extracts influences the excretion of mutagens and promutagens in the urine of animals.

Several epidemiological studies suggest that tea and its associated compounds may prevent some, but not all, cancers.

This is understandable, because cancer is a complex disease with multiple etiologies, even for one body site.

It is, therefore a false hope that any nutritional or synthetic agent can prevent or treat all cancer types.

However, based on a large volume of cell culture, animal studies and human observational studies, there is hope that green tea consumption can retard cancer development at selected sites in some populations.

The challenge is to elucidate what cancer type can be prevented by tea. This requires extensive research for which considerable resources are required.
Tea and Cancer