The Science of Tea
Tea is one of the most widely-consumed beverages in the world, second only to water. It has a rich mythical, culinary, medicinal, and political history, and it has changed the face of the world many times over throughout history. Legend has it that tea was discovered around 3000 BC in China by Emperor Shen Nong, the Divine Farmer, who is also credited with bringing agriculture and Chinese herbal medicine to the east. The Emperor was said to have been boiling water under a tree bush when a tea leaf fell into the boiling pot to make the first cup of tea. The custom of decocting tea leaves has since spread throughout China and the world, and has lead to what we now behold as modern global tea consumption. Thirty-four countries grow and export tea, with black tea being the most common variety.
There are four main types of tea; green, black, oolong, and puer – and they all come from the same species of plant – Camelia sinensis! Camelia sinensis is what all little teas are born from, with the differences stemming from how they are ‘raised.’ Green tea is steamed or pan fried almost immediately after picking, which haults the oxidative process and imparts a characteristic grassy flavor. Black tea is heavily fermented and allowed to oxidize, which changes it’s caffeine and polyphenol content, as well as taste and appearance. Oolong tea is oxidized in a range somewhere between green and black tea. Puer is the most fermented of all, undergoing anywhere between 1-100+ years of fermentation, and can be considered an herbal medicine.
Ancient cultures discovered the healing properties of tea, and have been using it for centuries.
Tea Drinking is Good for Health, written in Japan in 1211 by Eisai Myoan, describes various medicinal uses of tea; among them curing lack of appetite, remedying diseases caused by poor quality drinking water, paralysis, boils, and beri beri, which is a vitamin B deficiency. In both traditional Indian and Chinese medicine, practitioners have used green tea as a stimulant, a diuretic, an astringent, and to improve heart health. The Chinese classify green tea as an ‘energetically cooling’ beverage that can deplete digestive Qi, and is considered by some to be avoided during winter. Black tea, in contrast, is considered warming and promotes digestion. Post-fermentation puer is in it’s own category and goes through a microbial fermentation process. This tea is seen as being very much alive, as it is ferments up until it is brewed, and improves in quality as it ages like wine. In China, high quality Puer is viewed by some people as potent medicine, on par with qi gong, tai ji, and acupuncture, that can greatly benefit health and digestion.
The benefits of drinking tea are becoming more and more pervasive into Western consciousness.
Research into the benefits of tea for health promotion is staggering, with the vast majority of research showing a multitude of benefits available to us through this amazing and unique plant. Tea has been shown in studies to help treat and/ or prevent atherosclerosis, high cholesterol, many types of cancer (bladder cancer, breast cancer, ovarian caner, esophageal cancer, pancreatic cancer), diabetes, liver disease, and cavities. Japanese and Chinese populations, who drink tea regularly, have been shown to have one of the lowest incidences of prostate cancer in the world. Camellia sinensis has also been shown to have a wide range of antioxidant, anti-inflammatory, anti-carcinogenic and antibacterial activity against numerous pathogens.
The Science-y Stuff
Green Tea
Green tea contains 30-42% of it’s dry weight in polyphenols, which are complex antioxidants found in plants that protect human cells from the adverse effects of reactive oxygen species. In particular, green tea contains the polyphenol derivative Epigallocatechin-3-gallate (EGCG), which comprises 25-40% of total catechin load of green tea. EGCG is an anti-mutagenic that can prevent tumerogenesis by scavenging free radicals. EGCGs can also prevent several stages of carcinogenesis, including DNA damage and stabilization.
Green tea has more amino acids than black tea. It also contains the vitamins carotene, riboflavin, nicotinic acid, pantothemic acid, ascorbic acid, and theanine that is largely lost in the oxidation of black tea. According to one study conducted at UCSI University, “polyphenols are also known for their antibacterial activity. In general, antibacterial activity decreases when the extent of tea fermentation is increased, implying stronger activity in green tea than black tea.”
Black Tea
Fermentation of black tea causes the catechins that are normally found in green tea to oxidize and form different types of polyphenols called oligomeric flavanols, which include theaflavins and thearubigan, with thearubigins being the most abundant phenolic fraction of black tea. Theaflavins are orange-red compounds responsible for the astringent taste and coppery color of black tea. Theaflavins have been shown to have potent anti-HIV activity, lower blood cholesterol levels, and regulate cancer growth, survival, and metastasis, among a myriad of other things. Regular consumption of black tea has been shown to promote general homeostasis in humans.
Puer Tea
Puer tea decreases in polyphenol content as it ferments, corresponding inversely to an increase in fungi levels. This is thought to play a part in increasing Puer’s nutritional properties.
Some Health Considerations
According to Natural Medicine Comprehensive Database, green and black tea is loosely linked with exacerbating iron malabsorption of already iron-deficient populations. However, one study has suggested that black tea’s iron-chelating ability is greater that green tea. Also, green and black teas contain varying levels of caffeine and are sometimes linked with the adverse issues that are indicated with heavy caffeine intake. Caffeine levels in tea are often lower than the levels that can be found in other sources, such as coffee or OTC pills. For example, on average tea contains 47 mg of caffeine per 8 fl ounces, where coffee can contain around 95 mg of caffeine per 8 fl ounces. Black tea contains more caffeine than green tea. Low quality puer has also been shown to cause fluorosis in China and Tibet.
Pesticides are sometimes present in tea. In a study done by the Tea Research Institute in Hangzhou, China, eighty-eight pesticide residues were detected in tea using mass spectrometry. Aluminum and Arsenic are also possible heavy metal contaminants of tea grown in contaminated land or land with inorganic agricultural processes. Most tea production relies on the cultivating and harvesting of low-lying tea bushes are susceptible to pesticide contamination. The exceptions are teas from organic tea plantations and certain types of Puer which are harvested from old growth “tree forests” from mature trees rather than bushes. Although there are some possible health detriments associated with tea, they seem to mostly stem from two issues, the first and most pressing being industrial and pesticide contaminants. Because of the nature of agriculture in countries like China it is hard to guarantee that the plant has been cultivated in an ecologically responsible way.
There is an energetic quality associated with the different teas, as with any herb in Chinese medicine, which can either promote energetic homeostasis in an individual, or inhibit it. Care should be taken in the purveyance of tea and the method in which it is imbibed. By and large, however, most indigenous knowledge of tea, as well as western objective research, confirms the beneficial nature of all types of tea, and tea should be utilized and enjoyed by those who wish to benefit from this miraculous and powerful plant.
Call 1-919-230-2456 now to schedule a free consultation if you would like to start utilizing the millennia-old practice of Chinese herbal medicine to optimize your health and restore the resources that your body has to heal. The Fountain Acupuncture and Herbal Medicine is centrally located in Cary, NC, serving Cary, Raleigh, Durham, Apex, Garner, Wake Forest, Fuquay, and the greater North Carolina research triangle. We provide acupuncture in Cary, NC, as well as a host of broader Chinese medicine modalities, including Chinese herbal medicine, cupping, moxibustion, and nutritional and dietetic counseling.
In Health,
Kristin ten Broeck, MSOM, LAc