Camellia Sinesis (Tea)

Tea
Tea Uses and Benefits - image to repin / share
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Camellia Sinesis - Background

Grown throughout the world, the Camellia sinesis plant - from which we derive "tea" - thrives in humid environments. ^[1] Plants grown at high elevations and subtropical climates produce the highest-quality teas (these factors slow the plants' growth, which greatly improves flavor).

Many claims have been made regarding the supposed health benefits of tea. Descriptions of tea as having healing properties have been traced back to the earliest of Chinese texts. ^[2] Tea has been used for centuries by Nomadic peoples and physical laborers for its ability to ward off of fatigue, hunger and exhaustion.

In England during the 17th century, tea was advertised in shops as a health beverage that would cure headaches, colds, fevers and stomaches. It was also promoted as a tonic to increase alertness and surpress the appetiete ^[2]

Camellia Sinesis - Scientific Studies

Tea is considered by many cultures to prevent and combat various diseases, including cancer. For this reason, it has been the object of scientific study in recent years. The results of these studies are varied: In some cases, tea was found to have disease-preventing properties. However, more research must be carried out before a consensus is reached.

In a 2007 study, tea was found to contain over 700 different compounds, many of which are recognized for their potential to fight disease. Among these compounds, the most widely-recognized and well-understood are flavinoids, amino acids, vitamins and polysaccharides. Tea varieties--green, black, white and oolong--were found to contain high concentrations of antioxidants, which indicates that they may possess anti-tumor and anti-aging properties.

Regular consumption of tea may improve the body's intestinal balance by increasing the presence of beneficial microorganisms, while ridding the body of harmful bacteria. Tea leaves contain high concentrations of vitamin C, which is known to destroy cancer-causing free-radicals. Due to its low glycemic index and potent cleansing properties, tea consumption has been associated with the prevention of coronary heart disease and diabetes.

In a 2010 study, researchers discovered that cognitive decline occured more often in non-tea drinkers than in those for whom tea-drinking is a regular activity.

Processing of Tea

Native to the mountainous regions of Southern Asia, tea is the most widely consumed beverage in the world today. All varieites of tea--green, black, oolong and white--are made from leaves of the Camellia sinesis plant.

Black Tea - Of all teas made from Camellia sinesensis leaves, black tea undergoes the most processing. The mature leaves are picked, and then left to wilt for several hours. The leaves are then rolled and left for several hours; once the oils are oxidized, they are placed in an oven at 200 degrees Farenheit until they are nearly dry. Finally, they are heated over a fire to finish the drying process.

Oolong Tea - Oolong tea processing is very similar to that of black tea. The first steps--wilting and rolling--are the same. However, the leaves are left to oxidized for a shorter period of time. Once the veins of the leaves are reddish-brown, the leaves are heated in order to stop the oxidation process. The shelf-life of oolong tea is generally longer than that of black tea because oolong is heated at a higher temperature, which dries out the leaves and reduces the likelihood of mold growth.

Green Tea - In the Chinese method, Green tea is first wilted for a very short time, if at all. The leaves are neither rolled nor left to oxidize. The leaves are then toasted in a pan at low heat to prevent oxidation. In the Japanese method, the leaves are steamed instead of toasted. The leaves are rolled tightly or loosely depending on the type of tea desired (i.e. to make Gunpowder tea, the leaves are rolled tightly into tiny pellets, whereas other varieties are hardly rolled at all).

White Tea - Young buds of the Camellia sinesensis plant are processed to make white tea. The leaves are wilted at a low temperature in a humidity- controlled environment for over 26 hours. The leaves appear "white" because they are sheilded from sunlight during the oxidation process.

Tea - Scientific Studies And Research

The consumption of tea (Camellia sinensis) has been determined by a number of laboratory studies to be effective in preventing chronic diseases such as obesity, a notorious risk factor of type II diabetes, liver and cardiovascular diseases, and cancer. ^[3] Tea contains catechins, particularly (-)- epigallocatechin gallate, which have been reported to exert antiobesity and antidiabetic effects through mechanisms related to pathways involved in energy balance regulation, food intake, or lipid and carbohydrate metabolism. ^[4] The results from a Japanese study indicated that tea catechin supplementation in the diet significantly reduces body weight gain induced by a high-fat diet and suppresses the accumulation of visceral and liver fats and the development of hyperinsulinemia and hyperleptinemia. Furthermore, the 1-month consumption of tea catechins resulted in an increased acylCoA oxidase and medium-chain acyl-CoA dehydrogenase mRNA expression as well as beta-oxidation activity in the liver. Hence, it appears that the stimulation of lipid catabolism in the liver might be a factor responsible for the antiobesity effects of tea catechins. ^[5] Because tea catechins are helpful in the prevention of diet-induced obesity, by extension, they also hold a promising potential in the reduction of risk of a few diseases such as diabetes and coronary heart disease.

The potential preventive and inhibitory activity of tea and its polyphenols against cancer has been well studied in several kinds of animal models, such as cancer of the skin, lung, oral cavity, esophagus, stomach, liver, pancreas, small intestine, colon, bladder, prostate, and mammary gland. ^[6] For instance, green tea and black tea, as well as their corresponding constituents, have been demonstrated in various animal models to inhibit the formation of lung tumors, including those induced by tobacco smoke- related carcinogens such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), benzo[a]pyrene, and N-nitrosodimethylamine and those lung tumors spontaneously developed in A/J mice. ^[6] An association between tea consumption and a decreased risk of stomach, prostate, and ovarian cancers has also been reported by case-control studies and some cohort studies. ^[6] Although a lot still needs to be investigated and studies have not yet yielded clear-cut convincing conclusions, a few mechanisms on how tea possibly contributes to the prevention of specific types of cancer have been proposed. These include the modulation of signal transduction pathways that leads to the inhibition of cell proliferation and transformation, induction of apoptosis of preneoplastic and neoplastic cells, and inhibition of tumor invasion and angiogenesis. ^[8]

Many of the beneficial effects of tea on health have been attributed to the antioxidant action of its catechins and polyphenols. Tea catechins serve as effective scavengers of reactive oxygen species in vitro and indirectly act on transcription factors and enzyme activities. ^[9] They do this by functioning as a strong metal ion chelator (e.g., chelator of free Fe3+ ions) to prevent the formation of reactive oxygen species or by "trapping" reactive species such as superoxide radical, singlet oxygen, hydroxyl ROS, nitric oxide, nitrogen dioxide, and peroxynitrite. ^[6] Reactive oxygen species are chemically active molecules associated with considerable damage to cell structures, including DNA, and oxidation of polyunsaturated fatty acids and amino acids when they accumulate in the body in unregulated or increased amounts. ^[10]

Tea - Molecular Components and Chemistry

The primary and dominant active components of teas are polyphenols and caffeine. The polyphenols characteristic of tea are catechins, especially (-)-epigallocatechin-3-gallate - the most abundant, most active, and most studied one. Other catechins present in tea include (-)-epigallocatechin, (-)-epicatechin- 3-gallate, and (-)-epicatechin, with gallocatechin, epigallocatechin digallates, epicatechin digallate, and 3-O-methyl EC being found in smaller quantities. Tea also contains flavonols, including quercetin, kaempferol, myricitin, and their glycosides. ^[6]

Camellia Sinesis in old Herbals & Pharmocopœia

The Book of Tea - by Kakuzo Okakura (1906): THE CUP OF HUMANITY Tea began as a medicine and grew into a beverage. The tea plant a native of southern China was known from very early times to Chinese botany and medicine. It is alluded to in the classics under the various names of Tou Tseh Chung Kha and Ming and was highly prized for possessing the virtues of relieving fatigue delighting the soul strengthening the will and repairing the eyesight It was not only administered as an internal dose but often applied externally in form of paste to alleviate rheumatic pains. The Taoists claimed it as an important ingredient of the elixir of immortality. The Buddhists used it extensively to prevent drowsiness during their long hours of meditation.

References:

[1] Gautier, Lydia and Jean-Francios Mallet. Tea: Aromas and Flavors around the World. 2005. Chronicle Books: San Francisco, CA.

[2] Hara, Yukihiko. Green Tea: Health Benefits and Applications. 2001. Marcel Dekker, Inc.: New York.

[3] Grove K. A. & Lambert J. D. (2010). Laboratory, epidemiological, and human intervention studies show that tea (Camellia sinensis) may be useful in the prevention of obesity. Journal of Nutrition, 140(3): 446-453. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821884/

[4] Kao Y. H., Chang H. H., Lee M. J., & Chen C. L. (2006). Tea, obesity, and diabetes. Molecular Nutrition & Food Research, 50(2): 188-210. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pubmed/16416476

[5] Murase T., Nagasawa A., Suzuki J., Hase T., & Tokimitsu I. (2002). Beneficial effects of tea catechins on diet-induced obesity: stimulation of lipid catabolism in the liver. International Journal of Obesity and Related Metabolic Disorders, 26(11): 1459-1464. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pubmed/12439647

[6] Yang C. S., Lambert J. D., Ju J., Lu G., & Sang S. (2007). Tea and cancer prevention: molecular mechanisms and human relevance. Toxicology and Applied Pharmacology, 224(3): 265-273. doi:10.1016/j.taap.2006.11.024. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698225/pdf/nihms33734.pdf

[7] Clark J. & You M. (2006). Chemoprevention of lung cancer by tea. Molecular Nutrition & Food Research, 50(2): 144-151. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pubmed/16425282

[8] Yang C. S., Maliakal P., & Meng X. (2002). Inhibition of carcinogenesis by tea. Annual Review of Pharmacology and Toxicology, 42: 25-54. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pubmed/11807163/

[9] Higdon J. V. & Frei B. (2003). Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions. Critical Reviews in Food Science and Nutrition, 43(1): 89-143. Retrieved 28 May 2013 from https://www.ncbi.nlm.nih.gov/pubmed/12587987

[10] Reactive oxygen species. Wikipedia. Retrieved 28 May 2013 from https://en.wikipedia.org/wiki/Reactive_oxygen_species

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