By Sean Davis
While frequenting my favorite tea shop in Ocean Beach, I once heard a story about the cancer fighting health benefits of tea. According to the story, the original founder of the tea shop had been diagnosed with cancer several years previous. He had talked to an old Chinese woman who told him “If you drink 100 cups of tea every day, the cancer will be cured.” He started the tea shop in order to help fund his new tea habit and after a relatively short period of time, the cancer had disappeared.
Tea is the second most commonly consumed beverage in the world. It is believed to have originated somewhere between northeast India and southwest China and Tibet. No one knows when tea was first discovered, but one creation myth states it was originally discovered by Shennong around 2700 BC. More than likely tea has been around in one form or another since man first learned how to boil water and long before there was any written history.
There are six major varieties of tea consumed that come from various subspecies of the plant Camellia Sinensis. These include, white, yellow, green, oolong, black, and pu-erh. There are several steps involved with turning tea leaves into tea, but the different varieties are primarily obtained first by undergoing varying amounts of oxidation before being dry-fired. White and green tea leaves are completely un-oxidized making them the least processed of all the different types of tea. The tea leaves of Oolong and black tea are often shaken or bruised to encourage oxidation before being heated. After Oolong has been partially oxidized heat is applied to halt the process of oxidation and trap the flavor into the leaf. Black tea, on the other hand, is completely oxidized before being heated. Different types of Pu-Erh undergo varying degrees of oxidation, however it is generally un-oxidized like green tea. What makes Pu-Erh unique is that it is fermented before being consumed. Pu-Erh is sort of like the fine wine of teas in that it is classified in terms of how long it has been aged and what region it comes from.
There are over 700 known chemicals found in the Camellia Sinensis species. Among these are theanine, theobromine, theophylline, fluorine, bioflavonoids, amino acids, and polyphenols, as well as a form of antioxidant known as “catechins”. Catechins compose up to 30% of the dry weight of a tea leaf. Although they are broken down by the oxidative process used to make black tea they are still found in large enough quantities to measurably decrease the amount of free radicals in the body1. According to the free radical theory of aging, cells begin to degrade because they accumulate free radicals over time. Once cell degradation begins to take place, the cells no longer replicate perfectly and we begin to age. If this theory is true, then tea may actually keep our bodies younger by reducing wear and tear at the molecular level.
Several of the chemicals in tea are thought to have anti-cancer properties. The consumption of bioflavonoids, also called Vitamin P, has been shown to produce enzymes which help to eliminate mutagens and carcinogens. Bioflavonoids protect Vitamin C, a strong antioxidant, from being oxidized by free-radicals. Unlike Vitamin C, however, once a flavonoid is consumed it is treated like a foreign body and is rapidly metabolized by the body and excreted through the urine or deposited into the bile. This process of breaking down the flavonoids induces the production of “Phase 2” enzymes which also attack carcinogens and mutagens in the body. Basically, by introducing a small amount of what the body considers to be an irritant, the body goes through a strong metabolic process that removes all irritants, including potential cancer cells. This is similar to one of the current western theories of acupuncture that posits that acupuncture is able to reduce inflammation in the body by first creating a low level of inflammation at a specific site. The body’s response to this low level of inflammation is to reduce inflammation everywhere, not just at the original site of insertion. So in a way, bioflavonoids are like acupuncture for the cells. It has also been recently discovered that flavonoids increase the activation of nitric oxide synthase, which prevents inflammation of the blood vessel walls and lowers blood pressure, both of which are critical in preventing heart disease. Furthermore it is thought that flavonoids play a key role in preventing neuro-degenerative diseases2. The primary form of bioflavonoid found in brewed tea is the catechin. In one study rats were given a single modest dose of a catechin commonly found in dark chocolate. Ninety minutes later a stroke was induced in the rats with the control group showing significantly more brain damage than the group given the catechin9. Catechins have also been shown to protect the heart by breaking down recently formed atherosclerosis by 73% or more3, they protect the skin from UV radiation-induced carcinogenesis4, and they have antibiotic-like properties by acting as a germicidal and germistatic which disrupts the DNA replication process of bacteria5.
Theanine, an amino acid derivative found in large quantities in tea, is an analogue of glutamine and glutamate and it is able to cross the blood-brain barrier. Glutamine is an amino acid which is used as a source of cellular energy in the mitochondria, similar to glucose. It is also used functionally to repair cells after trauma, burns, and the side-effects from cancer related therapies. Glutamine is consumed most readily by the intestines, the kidneys, activated immune cells, and various analogues of glutamine are marketed as anti-cancer drugs (Azaserine, Acivicin). Glutamate, on the other hand, plays a key role in the citric acid cycle and helps the body to dispose of excess nitrogen. Glutamate is also the primary excitatory neurotransmitter of the central nervous system and it is the precursor to GABA which is the primary inhibitory neurotransmitter in the central nervous system. Theanine, although chemically similar to the excitatory neurotransmitter Glutamate, has a weak affinity for the glutamate binding sights in the brain. Instead it is seen to have a strong effect on stimulating GABA production which reduces psychological and physiological stress10. This reduction in stress levels elevates the mood and increases cognitive ability. Theanine is also suspected to bolster the immune system. In one study, tea drinkers were shown to have five times the level of anti-bacterial proteins in their blood when compared to coffee drinkers11.
Theobromine, another substance found in tea, is in the methylxanthine class of pharmaceutical substances along with caffeine. It is used in modern day medicine as a vasodilator to reduce blood pressure, a diuretic which can treat edema, and as a heart stimulant which can be used to treat congestive heart failure6. In addition, it has been patented for future use in cancer prevention12. Theophylline, an isomer of theobromine, has been used in the past to treat chronic obstructive pulmonary disease, and asthma, however it is found in tea at approximately 1mg/L which is far below the therapeutic dose. In addition to all of the above health benefits associated with drinking tea, research has shown tea to be beneficial to the microflora of the intestines and the fluorine found in tea strengthens the teeth and protects from dental cavities7. In 1999, a study that was published in the Nutrition journal stated that although all of these health benefits have been found in mammals in vitro, the quantities of tea needed to obtain the data far surpassed what the average person would consume in a day8. Since then the vast majority of research that has been done has been overwhelmingly positive regarding the health benefits and the anti-cancer properties of tea. Just to be safe, if one wants to fight cancer by drinking tea, they should drink a hundred cups every day!
• "Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods – 2007". Webcitation.org. 2009-05-23
• "Studies force new view on biology of flavonoids", by David Stauth, EurekAlert!. Adapted from a news release issued by Oregon State University.
• Chyu KY; Babbidge, SM; Zhao, X; Dandillaya, R; Rietveld, AG; Yano, J; Dimayuga, P; Cercek, B et al. (May 2004). "Differential effects of green tea-derived catechin on developing versus established atherosclerosis in apolipoprotein E-null mice". Circulation 109 (20): 2448–53. • Katiyar S, Elmets CA, Katiyar SK (May 2007). "Green tea and skin cancer: photo-immunology, angiogenesis and DNA repair". J. Nutr. Biochem. 18 (5): 287–96.
• Gradisar H, Pristovsek P, Plaper A, Jerala R (January 2007). "Green tea catechins inhibit bacterial DNA gyrase by interaction with its ATP binding site". J. Med. Chem. 50 (2): 264–71
• William Marias Malisoff (1943). Dictionary of Bio-Chemistry and Related Subjects. Philosophical Library. pp. 311, 530, 573.
• Mondal, T.K. (2007). "Tea". in Pua, E.C.; Davey, M.R.. Biotechnology in Agriculture and Forestry. 60: Transgenic Crops V. Berlin: Springer. pp. 519–535
• Nutrition (Nov-Dec 1999). Tea and Health. 15. pp. 946–949
• Kimura K, Ozeki M, Juneja L, Ohira H (2007). "L-Theanine reduces psychological and physiological stress responses". Biol Psychol 74 (1): 39–45. doi:10.1016/j.biopsycho.2006.06.006
• Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J (2003). "Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses". Proc Natl Acad Sci USA 100 (10): 6009–14.
• US patent 6693104, "Theobromine with an anti-carcinogenic activity", granted 2004-02-17