Health benefits of green tea
Green tea is a powerful anti-oxidant. It also contains minerals that are important for wellbeing. It is made from Camellia Sinensis Theaceae leaves. Many of its benefits have been attributed to: epigallocatechin gallate (EGCG), which is a major component of green tea.
Green tea has multiple health-promoting effects. It has been scientifically proven to possess: anti-diabetic, anti-cancer, anti-obesity, anti-atherosclerotic, anti-viral and anti-bacterial properties (Suzuki, Miyoshi, & Isemura, 2012).
It also has anti-inflammatory properties which make it beneficial in preventing and treating inflammatory conditions such as liver disease and inflammatory tendon/muscle disorders.
More recently, it has been researched over its potential to assist in endurance exercise and the prevention and treatment of conditions such as tendinopathy, tendinitis, and delayed onset muscle soreness.
A tendinopathy is a condition affecting tendons characterized by pain and degeneration of that tendon, often associated with repetitive overuse or overloading. Achilles tendinopathy is an example of a common tendinopathy which research shows affects approximately 11 % of runners and 8 % of dancers (Vieira, Guerra, Oliveira, et al., 2015). There are 2 types of tendinopathies. Reactive and degenerative tendinopathies. Reactive tendinopathies are generally a result of the tendon being placed under a rapid increase in loading or alternatively via direct trauma to the tendon. In contrast, degenerative tendinopathies generally occur as a result of chronic overloading. This makes the tendon more structurally disorganised and reduces its ability to deal with the load. Evidence suggests that the mechanism behind tendon degeneration involves oxidative stress. Free radicals are always present in the body, and are needed for bodily functions, but excessive production can result in the breakdown of the important building blocks of tendons such as proteoglycans. Decreased levels of proteoglycans in tendons have been associated with a higher incidence of tendinopathies. In order to prevent the breakdown of proteoglycans, free radicals in the body need to be kept to a minimum. Studies have shown that trauma as well as environmental and physiological stresses can result in an increase in free radical production (Bestwick & Maffulli, 2004). Green tea is high in antioxidants which fight, and in some instances, may even prevent cell damage. The antioxidants in green tea help control the amount of free radicals, reducing oxidative stress and therefore helping to maintain healthy tendons.
Tendinitis is an inflammation of a tendon. Glycine is an amino acid found in collagen -which is a building block of tendons. The amino acid has the ability to modulate inflammation as well as to influence local circulation. When a tendon becomes inflamed it becomes disorganised and weakened. Evidence shows that the consumption of green tea is beneficial to tendinitis treatment in that it helps to improve collagen fibre organisation. It also helps to improve the deposition of type 1 collagen fibres (Vieira, Guerra, Marcondes, Cintra, & Pimentell, 2015). Type 1 collagen is important for healthy tendons as its the main building block that makes up tendons (Franchi, Trirè, Quaranta, Orsini, & Ottani, 2007). Green tea also contains anti-inflammatory flavonoids which directly help to decrease inflammation. Overall, green tea helps to restore the tendon back to its original state.
Green tea can enhance endurance exercises such as running or cycling. Muscles mostly rely on carbohydrates and fat as a source of fuel during endurance exercise. Green tea extract has been shown to improve endurance capacity by increasing the breakdown of fats which means that glycogen supplies aren’t depleted as readily (Murase, Haramizu, Shimotoyodome, Nagasawa, & Tokimitsu, 2004). This means that you have energy available to you to keep exercising for longer.
Delayed onset muscle soreness:
Delayed onset muscle soreness (DOMS) is a condition characterised by the presence of muscular pain post exercise. It is caused by micro-trauma to the muscle and involves an inflammatory process in the muscle. Research shows that green tea extract reduces muscle inflammation when used as an early intervention (Evans, Call, Bassaganya-Riera, Robertson, & Grange, 2010). The antioxidant properties of green tea, such as EGCG, have also been shown to improve muscle structure and function (Dorchies, Gallo, Patte-Reutenauer, Gayi, & Ruegg, 2010). Supplementation with green tea reduces oxidative stress induced by high intensity exercise, but hasn’t yet been shown to be effective in the prevention of “exercise-induced muscle damage” (Jowko, Długołecka, Makaruk, & Cieslinski, 2015).
Evidence shows that consuming 6 or more cups of green tea daily reduces the risk of developing type 2 diabetes by 33% (Iso, Date, Wakai, Fukui, & Tamakoshi, 2006). Green tea has also been found to regulate blood glucose levels by improving glucose tolerance and the body’s sensitivity to insulin (Venables, Hulston, Cox, & Jeukendrup, 2008).
Cancer cells are abnormal cells that divide uncontrollably and evade programmed cell death. The antioxidant, EGCG, in green tea encourages programmed cell death to occur (apoptosis), thus reducing their replication capabilities (Suzuki et al., 2012). Some cancers have the ability to spread (metastasise) to other tissues causing tumours to develop. EGCG has been shown to reduce the metastasis of cancer by inhibiting the cancer cells from sticking to basement membranes (Sazuka, Murakami, Isemura, Satoh, & Nukiwa, 1995). Research has shown green tea is effective against a large variety of cancers including pancreatic, stomach, oesophageal, lung, prostate and breast cancer.
Consumption of green tea has been associated with increased fat oxidation, improved exercise performance and obesity prevention. Studies have shown drinking green tea habitually has been linked to a “lower body fat composition and smaller waist circumference”(Wu et al., 2003).
Green tea consumption is associated with a decreased mortality rate from all causes including from cardiovascular disease. Evidence shows it is effective at reducing low density lipoprotein cholesterol (LDL’s), chronic inflammation including vascular inflammation, blood pressure and oxidative stress (Kuriyama, 2006).
Anti-viral and anti-bacterial properties
Green tea extracts have antibacterial effects against a wide variety of disease causing bacteria. Research has also shown promising results against antibiotic-resistant bacteria such as methicillin-resistant staphylococcus aureus (Cho, Schiller, & Oh, 2008). Green tea also has antiviral properties. The antiviral properties have been found to be effective against various viruses such as the influenza, HIV, adenovirus and many more (Song, Lee, & Seong, 2005).
Bestwick, C. S., & Maffulli, N. (2004). Reactive oxygen species and tendinopathy: do they matter? British Journal of Sports Medicine, 38(6), 672-674. doi: 10.1136/bjsm.2004.012351
Cho, Y., Schiller, N. L., & Oh, K. (2008). Antibacterial effects of green tea polyphenols on clinical isolates of methicillin-resistant staphylococcus aureus. Current Microbiology, 57, 542–546. doi: 10.1007/s00284-008-9239-0
Dorchies, O. M., Gallo, C., Patte-Reutenauer, J., Gayi, E., & Ruegg, U. T. (2010). P3.44 Green tea polyphenols enhance the motor performance of the mdx5Cv dystrophic mouse and normalize calcium influx in muscle fibres. Neuromuscular Disorders, 20(9), 654–655. doi: 10.1016/j.nmd.2010.07.186
Evans, N. P., Call, J. A., Bassaganya-Riera, J., Robertson, J. L., & Grange, R. W. (2010). Green tea extract decreases muscle pathology and NF-κB immunostaining in regenerating muscle fibers of mdx mice. Clinial Nutrition, 29(3), 391–398.
Franchi, M., Trirè, A., Quaranta, M., Orsini, E., & Ottani, V. (2007). Collagen structure of tendon relates to function. Scientific World Journal, 30(7), 404-420.
Iso, H., Date, C., Wakai, K., Fukui, M., & Tamakoshi, A. (2006). The relationship between green tea and total caffeine intake and risk for self-reported type 2 diabetes among japanese adults. Annals of Internal Medicine, 144(8), 554-563.
Jowko, E., Długołecka, B., Makaruk, B., & Cieslinski, I. (2015). The effect of green tea extract supplementation on exerciseinduced oxidative stress parameters in male sprinters. European Journal of Nutrition, 54(5), 783–791. doi: 10.1007/s00394-014-0757-1
Kuriyama, S. (2006). Green tea consumption and mortality due to cardiovascular disease, cancer, and all causes in Japan. Journal of the American Medical Association, 296(10), 1255-1265. doi: 10.1001/jama.296.10.1255
Murase, T., Haramizu, S., Shimotoyodome, A., Nagasawa, A., & Tokimitsu, I. (2004). Green tea extract improves endurance capacity and increases muscle lipid oxidation in mice. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 288(3), 708-715. doi: 10.1152/ajpregu.00693.2004
Sazuka, M., Murakami, S., Isemura, M., Satoh, K., & Nukiwa, T. (1995). Inhibitory effects of green tea infusion on in vitro invasion and in vivo metastasis of mouse lung carcinoma cells. Cancer Letters, 98(1). doi: 10.1016/0304-3835(95)03993-7
Song, J., Lee, K., & Seong, B. (2005). Antiviral effect of catechins in green tea on influenza virus. Antiviral Research, 68(2), 66–74. doi: 10.1016/j.antiviral.2005.06.010
Suzuki, Y., Miyoshi, N., & Isemura, M. (2012). Health-promoting effects of green tea. Proceedings of the Japan Academy, 88, 88-101.
Venables, M., Hulston, C., Cox, H. R., & Jeukendrup, A. E. (2008). Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. The American Journal of Clinical Nutrition, 87(3).
Vieira, C. P., Guerra, F., Marcondes, A., Cintra, M., & Pimentell, E. R. (2015). Green tea and glycine aid in the recovery of tendinitis of the Achilles tendon of rats. Connective Tissue Research, 56(1), 50-58. doi: 10.3109/03008207.2014.983270
Vieira, C. P., Guerra, F. D. R., Oliveira, L. P. d., Almeida, M. S., Marcondes, M., & Pimentell, E. R. (2015). Green tea and glycine aid in the recovery of tendinitis of the Achilles tendon of rats. Connective Tissue Research, 56(1), 50-58. doi: 10.3109/03008207.2014.983270
Wu, C. H., Lu, F. H., Chang, C. S., Chang, T. C., Wang, R. H., & Chang, C. J. (2003). Relationship among habitual tea consumption, percent body fat, and body fat distribution. Obesity Research, 11(9), 1088–1095. doi: 10.1038/oby.2003.149
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