Recent Research on Breast Cancer
Warnings re Oesophageal Cancer and Shelf Life
Tea in a capsule - Tegreen 97*
The health benefits of tea are well known.
Drinking tea is beneficial to the heart and cardiovascular system and prevents or delays cognitive decline, as well as having numerous other positive effects on the body. Details concerning these benefits have been set out in my September 2007 newsletter A Cup of Tea = A Cup of Good Health and my August 2008 newsletter Tea and Health Benefits - Two Recent Studies.
This newsletter adds details of more recent research into tea and our health.
Recent Research in Breast Cancer
To study the effect on beast tumours, a team of US researchers led by Dr Nagi Kumar at the Moffitt Cancer Centre in Tampa, Florida, studied 5,000 women between the age of 20 and 74 years who had been treated for breast cancer.
The medical histories and lifestyles of this group of 5,000 cancer victims were compared with those of a similar (control) group of women who were free of breast cancer.
The results were published in 2008 in the journal Cancer Epidemiology Biomarkers and Prevention.
Women, under 50 years of age, who drank three or more cups of tea a day were 37 percent less likely to have breast tumours than women who drank no tea at all. The benefits were even greater when it came to ‘lobular’ breast cancer, where tea reduced the risk by 66 percent. (Lobular cancer affects the lobes deep inside breast tissue, occurs in one in ten breast cancer cases, and is often quite advanced by the time it is diagnosed.)
Tea consumption did not appear to protect older women against the disease.
The researchers said: “Regular tea consumption, particularly at moderately high levels, might reduce breast cancer risk in younger women. …. it [tea] makes an attractive candidate for breast cancer prevention.”
This study gives further support to the health benefits of drinking tea.
Green tea has higher quantities of the beneficial compounds called flavonoids than black tea, since some of these are lost in the oxidation process that black tea undergoes. In the above study, the type of tea was not indicated. However, black tea is more commonly drunk, so it would be expected that black tea would have been the main type consumed in the study.
Green tea would be the tea of choice to help prevent the various diseases that have been shown to benefit from drinking tea. Three to five cups a day would confer greatest benefit.
A Warning re Oesophageal Cancer
In my September 2007 newsletter A Cup of Tea = A Cup of Good Health , “How to Brew a Cup of Tea” was set out.
Part of the directions for brewing black tea was to add boiling water to the tea leaves or the teabag. This was in contrast to the recommended temperature of the water in making green tea, namely 80 degrees C (ie not boiling). These temperatures make the best tea (black and green), especially when made from leaves, and release maximal amounts of the beneficial flavonoids, as well as giving the full taste.
An article recently published in the British Medical Journal (March 26, 2009), showed that drinking steaming hot tea has been linked with an increased risk of oesophageal cancer. 300 proven (by biopsy) cases of oesophageal squamous cell carcinoma were compared to 571 matched controls. 98% drank black tea regularly, with a mean volume consumed of over one litre per day. Compared with drinking warm or lukewarm tea, drinking hot tea (65-69 degrees C) was associated with twice the risk of oesophageal cancer, and drinking very hot tea (70 degrees C or more) was associated with an eight-fold risk. The setting for this study was Golestan province, northern Iran, an area with a high incidence of oesophageal cancer.
Oesophageal cancer is said to kill more than 500,000 people worldwide each year.
In the above study, black tea only was referred to. It is of interest that in Iran and Afghanistan, “tea is the national beverage. Both green and black are used – green as a refreshing thirst quencher and black as a warming comforting brew, and both types are taken with sugar.” (www.foodreference.com)
Drinking very hot beverages of any kind can increase the risk of oesophageal cancer. The greatest risk comes at temperatures 70 degrees C or higher.
Simply wait a few minutes after brewing for the tea to cool from ‘scalding’ to ‘tolerable’ before drinking.
Ideally, get into the habit of drinking your beverages towards room temperature, as those that are too hot can damage the oesophagus, while those that are to cold can harm the delicate lining of the stomach.
Do not let the above deter you from drinking tea! There are real health benefits from drinking tea, as this and previous newsletters explain.
How to brew the tea, as set out in my September 2007 newsletter, is correct. When milk is added to black tea (not recommended), the tea is cooled. Both black and green teas should be allowed to steep for at least two minutes. Then allow this brew to stand for a few minutes as mentioned above. This will mean that adequate cooling will take place. Avoid drinking the very hot tea that can result from the use of tea-bags, where the brew is almost instantaneous, and the water still near to boiling.
Do not drink the tea while it is very hot.
A Warning re Shelf Life
Choice, the publication of the Australian Consumers’ Association, under the heading of ‘Consumer News’, referring to ‘Tea Antioxidants’, said: “Shelf time proves risky. Green tea has long been prized for its antioxidants, but new research suggests even short-term storage drastically reduces its health benefits” (June 2009).
What was the basis of this warning, and how serious is this claim?
The study, Stability of Green Tea Catechins in Commercial Tea Leaves During Storage for Six Months, published in the Journal of Food Science (2009), looked at levels of catechins in green tea samples bought from stores in the US, Japan and Korea. A research team led by Mendel Friedman found that all samples lost catechins after six months of storage in a dark place at 20 degrees C - similar to conditions in a cupboard or pantry. Loss ranged from 14% to 88%, with an average loss of 32%.
Tea has high levels of flavonoids, a class of antioxidants to which catechins belong. These flavonoids are the potent antioxidants of tea, especially green tea, and are the active ingredients of tea that give the health benefits.
It has been pointed out by Nigel Melican (managing director of Teacraft Ltd) that there were several short comings in the study’s methods: Initial moisture content of the samples and acquired moisture content throughout storage were not measured. Nor were the range and mean temperatures, as well as humidity conditions, provided. He indicated that storage methods of tea bags, which have “a profound effect on moisture uptake and or loss”, were not described in detail.
It is therefore important to buy fresh tea and not keep it for prolonged periods of time before use, unless properly stored.
The teas tested in the above study were in tea bags. Whole leaf teas are preferable. The supply of tea by specialist outlets, for example T2Tea, is in the form of tea leaves in sealed packaging.
The website of T2Tea (www.t2tea.com.au) sets out the recommended way to store tea:
“Tea has four main ‘enemies’: air, light, heat and moisture. Prolonged exposure to any of these elements will cause the quality of your precious leaf to deteriorate. The correct storage vessel should be airtight (a double lid is one of the best ways to store tea), light-proof, should be made of a non-aromatic substance like metals, glass, or porcelain, and should be kept in a cool, dry environment away from direct sunlight and overpowering odours. Tea will last for up to 2 years if stored under optimal conditions.”
Tea in a capsule - Tegreen 97
Tegreen 97 is an exclusive preparation of green tea extract (20:1) standardised to 97% polyphenols in which 65% are the catechins. Each capsule is equivalent to the polyphenol content of approximately 7 cups of green tea without caffeine. It is claimed by the manufacturer that Tegreen 97 is “one of the most concentrated level of green tea polyphenols available in a dietary supplement…” Each capsule contains: Green Tea Leaf Extract (20:1) 250mg. It is recommended, by the manufacturer Pharmanex, to take one to four capsules daily (www.completehealth.com.au).
A significant drawback is the cost (in excess of A$90 excluding delivery for 120 capsules). [Distributed in Australia by Nu Skin.]
Surely the great pleasure of green tea is in the brewing and the drinking!
*Copyright 2009: The Huntly Centre.
Disclaimer: All material in the Huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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