Green Tea - What are EGCG and Polyphenols?

Green Tea - What are EGCG and Polyphenols?

This infamous health promoter is extracted from the Camellia Sinensis plant which is endemic to the mountains of China. It is talll 17m plant that thrives at high altitudes and humid temperatures.

It produces small white singular flowers and brown spherical fruits. Within the fruits are flat disk-like seeds, however, the most widely used part of the plant are its leaves. The leaves are picked, steamed, and dried for use in herbal beverages [1]. The question is, what makes Green Tea so great? Why isn’t English Breakfast tea the new health craze?

The chemistry of what make Green Tea a health food staple is complex as it contains over 200 bioactive compounds. The answer to its health status are its active ingredients, Polyphenols, Catechins and Epigallocatechin Gallate.

What are Catechins?

Catechins are the most prominent therapeutic chemical found naturally in Green Tea. It’s thought that in an average serving of Green Tea, approximately 30-40% of it is made up of the polyphenol Catechins. Catechins are responsible for the astringency feature of tea. Astringency is described as the ‘dry-mouth feeling’ or ‘puckering-cheeks” feeling you get when drinking tea.

There are a number of Catechins, including variations of both Epicatechin and Epigallocatechin. The one chemical that has scientists celebrating is EGCG or Epigallocatechin-3-gallate. In Green Tea EGCG is unoxidised which gives way for antioxidant properties. Whereas in Black tea the Catechins are oxidised which reduce its health properties. On average Black tea contains 26% less Catechins than Green tea does [2,3].

What are the Health properties of Catechins?

Catechins possess the following properties, they are, antioxidative, anti-inflammatory, anti-thrombogenic (prevents blood clots), anti-hypertensive and lower blood lipid concentrations [4].

Catechins are one of natures greatest Antioxidants, thought to be over 100 times stronger than Vitamin C and 25 more powerful than Vitamin E [2]. Antioxidants are a complicated idea to understand but most importantly they are brilliant for health. Simply put, an antioxidant prevents oxidation. Oxidation occurs due to highly reactive free radicals, which are molecules that have one electron missing from their structure. In order for the free radical to become stable it must steal an electron from another structure, thus oxidising the other structure. When this occurs in vivo it causes damage to DNA, proteins and lipids leading to ill health. Antioxidants have been linked with the prevention of diseases such as Alzheimer’s, Fibromyalgia, Cancer and Macular Disease[4]. One study found that ingestion of Catechin rich Green tea vastly increased plasma antioxidant capacity. In animal studies Catechins showed promising effects on markers of oxidative stress (e.g damaged DNA and tissues)[5,6].

In addition to antioxidant properties, tea Catechins have also been shown to benefit the health of our heart and Cardiovascular System. As previously mentioned, Catechins are anti-hypertensive and prevent high levels of lipids in the blood, both of these qualities are beneficial to cardiovascular health. Catechins also activate cellular nitric oxide which is responsible for stimulating the width of blood vessels known as vascular tone. They are also anti-inflammatory, which means that they prevent vascular inflammation which could lead to Atherosclerosis. Lastly, they are anti-thromogenic which means it reduces blood viscosity preventing blockages in the vessels. One study found that over 40,000 Japanese males that drank approximately 17 ounces of Green Tea a day reduced their risk of cardiovascular disease by up to 33%. [4]

Weight loss is a massive market in the health industry. Technically Green Tea is included in this market. Obesity in Britain and many 1st world countries is at its highest rate in history. One study showed that regular intake of Green tea promoted weight loss. Furthermore, the weight was lost from fat tissue rather than lean muscle mass[7]. A study conducted in Japan looked at both males and females with high ratios of visceral fat. This clinical study showed a link between Green Tea consumption and a decrease in BMI, body weight particularly in visceral fat stores. Also, there were decreased measurements in hip and waist circumference [8].

Including the illnesses and disorders above, plus many others, Green tea has made a name for itself as one of the most protective and beneficial plants known in the supplement world.

  1. Botanical Online. (2016). Green Tea-Camellia Sinensis . Available:
  2. Amazing Green Tea. (2011). Green Tea Ingredients and Chemistry Explained. Available:
  3. Amazing Green Tea. (2012). EGCG, Catechins and Polyphenols FAQ Guide. Available:
  4. Velayutham.P, et-al. (2008). Green Tea Catechins and Cardiovascular Health: An Update. Current Medical Chemistry. 15 (18), Pg. 1840-1850.
  5. Preventative Health Guide. (2006). Understanding Oxidative Stres.Available:
  6. Higdon.JV, Frei.B. (2003). Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions.. Critical Review in Food Science and Nutrition . 43 (1), Pg.89-143.
  7. Bell.SJ, Goodrick.GK. (2002). A functional food product for the management of weight.. Critical Review in Food Science and Nutrition . 42 (2), Pg.163-78.
  8. Nagao.T, Hase.T, Tokimitsu.I. (2007). A green tea extract high in catechins reduces body fat and cardiovascular risks in humans.. Obesity. 15 (6), Pg. 1473-1483.
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