By: Emma Partridge, MS Candidate
Green tea contains a high concentration of polyphenols, most of which are flavanols. Flavanols are commonly known as catechins, the most active catechin being epigallocatechin-3-gallate (EGCG).1 Within the world of nutrition, green tea is consistently touted as a beverage with a plethora of health benefits. These benefits are far-reaching and specific roles of green tea have been identified to improve symptoms or reverse disease damage amongst people with autoimmune disease, heart disease, cancer, liver disorders, smoking complications, chronic inflammation, and more. The roles of green tea often overlap and while green tea consumption is important for those with various diseases, the consumption of green tea by healthy individuals may be integral in the prevention of many of the following diseases.
Chronic Inflammatory Disease
EGCG may be most important flavanol when it comes to inflammation control.2 EGCG has been shown to suppress the production of cytokines, pro-inflammatory mediators. Suppressing cytokines decreases long-term inflammation and has been shown to improve inflammation-related symptoms in arthritis models.3,4
In addition to helping to control the chronic inflammation associated with most autoimmune diseases, EGCG has been shown to suppress auto-reactive T cell proliferation. Auto-reactive T cells act against the body, resulting in various forms of autoimmune diseases. EGCG may also help to regulate T-helper cell balance, which may decrease the pathogenesis of arthritic diseases, especially rheumatoid arthritis.3
Type 2 Diabetes Risk
Type 2 Diabetes is sweeping America, and food production practices, availability, and affordability are making it harder for people to access healthy options. The ease of accessing and affording unhealthy foods is increasing the risk of diabetes among populations. Green tea, as well as coffee, has been associated with lowering the risk of type 2 diabetes, though the mechanism is unknown and the data inconsistent. However, in a study of 40,000+ people followed for 10 years, researchers found that daily consumption of at least three cups of coffee or tea may lower type 2 diabetes risk.5
Heart Disease & Stroke Risk
In an article published by the American Heart Association, researchers found that people who drank two to three cups of green tea per day had a 14% lower risk of stoke.6 The research on green tea and stroke risk comes on the wake of multiple studies finding links between green tea and heart health. Multiple studies found green tea consumption to lower risk of death from heart attacks by 26% and lower risk of coronary artery disease by 28%.7
Cancer & Tumor Growth
Cancer is a leading cause of death in the United States, behind heart disease. Green tea has already been shown to be beneficial in preventing the leading cause of death; now studies have now shown that the EGCG may affect transformed cells by inhibiting the growth of certain cell lines, inducing apoptosis, and altering gene expression to prevent transformed cells from becoming cancerous.8
The polyphenols in green tea have shown to work against carcinogens, while the antioxidant effects may reverse endothelial dysfunction in healthy smokers.8 The reversal of endothelial dysfunction in smokers is important because it plays a role in the pathogenesis of atherosclerosis and cardiovascular disease.9
Green tea’s aforementioned anti-carcinogenic affect may play a role in preventing liver disease. Active polyphenols detoxify reactive oxygen species, preventing oxygen free radicals from destroying hepatocytes and causing oxidative DNA damage. Multiple studies have shown that, most likely via this method, green tea intake can attenuate liver disease or liver cancer.10
Weight Loss & Weight Maintenance
Green tea’s affect on weight loss may be attributed to two components: EGCG and caffeine. Caffeine alone does play some role in increasing energy expenditure, but when combined with EGCG, the mixture stimulates energy expenditure and fat oxidation to a greater degree. This may trigger weight loss, and additional evidence reveals that continual green tea consumption can further help to maintain weight.11
In determining whether or not green tea is for you, the answer is likely yes. While there are risks by way of overconsumption, a few glasses a day has been shown to be beneficial for the all-around healthy person in preventing disease and for the person suffering from various diseases or ailments.
1.Ehrlich SD. Green Tea. 2011; http://umm.edu/health/medical/altmed/herb/green-tea.
2.Hamer M. The beneficial effects of tea on immune function and inflammation: a review of evidence from in vitro, animal, and human research. Nutrition Research. 2007;27(7):373-379.
3.Wu DY, Wang JP, Pae M, Meydani SN. Green tea EGCG, T cells, and T cell-mediated autoimmune diseases. Molecular Aspects of Medicine. 2012;33(1):107-118.
4.Kim HR, Rajaiah R, Wu QL, et al. Green Tea Protects Rats against Autoimmune Arthritis by Modulating Disease-Related Immune Events. Journal of Nutrition. 2008;138(11):2111-2116.
5.van Dieren S, Uiterwaal C, van der Schouw YT, et al. Coffee and tea consumption and risk of type 2 diabetes. Diabetologia. 2009;52(12):2561-2569.
6.Green tea, coffee may help lower stroke risk. 2013; http://newsroom.heart.org/news/green-tea-coffee-may-help-lower-stroke-risk.
7.Green tea may lower heart disease risk. Harvard Heart Letter 2012; http://www.health.harvard.edu/heart-health/green-tea-may-lower-heart-disease-risk.
8.Chen ZP, Schell JB, Ho CT, Chen KY. Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts. Cancer Letters. 1998;129(2):173-179.
9.Nagaya N, Yamamoto H, Uematsu M, et al. Green tea reverses endothelial dysfunction in healthy smokers. Heart. 2004;90(12):1485-1486.
10.Jin X, Zheng R-h, Li Y-m. Green tea consumption and liver disease: a systematic review. Liver International. 2008;28(7):990-996.
11.Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. International Journal of Obesity. 2009;33(9):956-961.