The second most popular beverage after water, consumed either hot or cold, is prepared from brewing the leaves of Camellia sinesis: green tea. Different from the equally popular black tea, the fermentation of the leaves is prevented, retaining the eponymous original green color [1].
For a long time, consuming green tea was associated with longevity and increased health, and indeed, green tea was shown to contain the highest concentrations of different polyphenols (flavinoids, catechins, caffeine, theanine, theobromine, theophylline, phenolic acids) as well as antioxidants (epigallocatechin gallate, catechin, epicatechin gallocatechin, gallocatechin gallate, and epicatechin gallate), all of which were shown to be associated with health benefits [2].
A multitude of studies, mainly performed in Asian countries where the plant is cultivated and drinking green tea has a tradition of almost 5000 years [3], reported the health benefits of green tea consumption in various diseases ranging from atherosclerosis, high cholesterol, diabetes, obesity, liver and bowel pathologies to almost all types of cancers [1,4]. In many different types of brain and peripheral nerve tumors, green tea and its extracts were found to inhibit cancer cell growth and render them more vulnerable to chemo- and radiotherapy while simultaneously sparing normal brain cells [5,6].
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Prof. Hunstein, a former internist and hematologist, provided a very intriguing self-report on the application of green tea in disease. He suffered from the rare condition lambda light-chain amyloidosis. Whilst the common therapeutic approach was rather ineffective, daily consumption of 1.5 to 2 liters of green tea per day reduced his symptoms substantially [7].
Meta-analyses of studies investigating the effects of daily green tea consumption reveal that there are major variations in the daily intake, concentration, and preparation methods of green tea, and have not found definite proof of clinically relevant benefits [1]. However, more recent studies have relied on chemically pure green tea extracts, more specifically epigallocathechin-3-gallate (EGCG).
This compound was shown to be beneficial for the central nervous system. Since green tea is associated with healthy aging, researchers investigated its effects in diseases of the elderly: Alzheimer's and Parkinson's disease.
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In vitro and in vivo models, similar to Prof. Hunsteins amyloidosis report, showed that EGCG decreases A-beta plaque burden by inhibiting peptide aggregation and promoting production of non-cytotoxic peptides through the modulation of secretase activity [8,9]. Additionally, green tea extract acts as an anti-inflammatory compound, scavenging free radicals and promoting hippocampal neurogenesis, all of which are beneficial in Parkinson's disease[10]. The extract does not only prevent cognitive decline by slowing down neurodegenerative processes, but was found to improve cognition even in healthy brains [11]. In small animal as well as human studies, researchers found evidence for the psychological relevance of green tea and its extracts. Reports indicate that green tea reduces stress and even has an antidepressant-like activity. [12,13]
Moreover, there is evidence that EGCG prevents cognitive deficits after stroke, in Huntington's disease and Down syndrome patients [14-16]. Another very promising trial - which was recently performed here at the Charité - investigated the anti-inflammatory actions of EGCG in multiple sclerosis (MS), an autoimmune disease with unknown origin that causes CNS damage by attacking the myelin sheath and causing inflammation and neuronal death [17]. Previous research groups, now present on the Charité campus, had found that EGCG strongly reduces symptoms in the EAE mouse model of MS. The green tea extract is a neuroprotectant and reduced general neuroinflammatory activity [18]. Regarding the now completed clinical trial, project leader Dr. Judith Bellmann-Strobl stated: “We currently evaluate the results of the SuniMS trial. We are about to unblind the data and only then we will know the effects. So far, I can only say that the investigational product was very well tolerated even at relatively high dosages.”
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| Camellia Sinensis, Source |
In conclusion, green tea consumption is very likely beneficial for the body, soul and disease prevention. However, treating individual diseases may require chemically pure compounds found in green tea extracts, which seem to exert few, if any, side effects. It appears that a healthy lifestyle is not only about veggies and exercise; have some green tea to pamper your brain!
[1] bit.ly/1azL2q3
[2] Johnson et al, Maturitas, 2012
[3] http://inventors.about.com/od/tstartinventions/ss/tea.htm
[4] Hursel et al, Am J Clin Nutr, 2013
[5] Das et al, Cancer, 2010
[6] Shervington et al, Mol Biol Rep, 2009
[7] Hunstein, Blood, 2007
[8] Jayasena et al, Ageing Research Reviews, 2013
[9] Lee et al, J Nutr, 2009
[10] Lee, Neurosignals, 2005
[11] Haque et al, J Nutr, 2006
[12] Zhu et al, Pharmacol Res, 2012
[13]Kimuras et al, Biol Psychol, 2007
[14] Suzuki et al, Med Sci Monit, 2004
[15] Kumar and Kumar, Food Chem Toxicol, 2009
[16] De la Torre, Mol Nutr Food Res, 2013
[17] http://www.gesundheitsforschung-bmbf.de/de/1053.php
[18] Aktas et al, J Immunol, 2004
by Bettina Schmerl, MSc Student Medical Neurosciences
this article originally appeared 2013 in CNS Volume 6, Issue 4, Integrative Medicine
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