Author: Nina Devrnja, PhD in Biology
Green tea or green tea extract: have you ever wondered what the difference is exactly? We summarize for you how the green tea extract differs from the pure green tea and how it is obtained. And above all, how “the gold of Asia” could support your wellbeing.
Once upon a time … There are many legends about the origin and history of green tea. These stories go back as far as five thousand years and show how important green tea is to Asian culture . According to legend, the father of Chinese medicine discovered green tea by chance. Shen Nong Shi dropped a leaf of the previously unknown plant into the teacup. He immediately felt the invigorating effect, and the triumph of green tea began.
Green tea: how it all began, its origin & meaning
No matter which of the legends is true. One thing is certain: With green tea, a new drink was created that influenced human history and changed the world. At first, the leaves of the tea plant were used for medicinal purposes. It was only later that green tea was also consumed as a drink.
Nowadays, tea is the most widely consumed drink alongside water and in many cultures it is also drunk on upscale social occasions. In Chinese and Japanese cultures, tea ceremonies have even emerged with an exact protocol of brewing and serving. This shows what high value the Asian population gave to green tea.
Tea production – what do we know about it?
China is not just a strong economic power. It is also the largest green tea producer with 480,000 tons of tea per year, followed by Japan, Vietnam, Indonesia and Russia. In total, the total tea production in the world amounts to approx. 3,000,000 tons per year, of which 70% is black tea and approx. 25% green tea.
Back to the roots: The tea plant from which the tea comes is called Camellia sinensis , also known under the name Thea sinensis. It has been grown in China for more than 2,700 years. Black tea, green tea, white tea, oolong tea, pu-erh tea and purple tea, all of these teas are made from Camellia sinensis. Each of these teas develop their unique properties through different harvesting and processing methods. They have been developed over hundreds of years and give them their characteristic taste.
Green Tea Vs. Black Tea: What’s the Difference?
There are two main types of green tea. Camellia sinensis var. Assamica, native to the Assam region of India, is a large-leaved tree that grows in warm climates. This variety is usually used in the production of black tea. However, the green tea made from this variety has a higher polyphenol content.
Camellia sinensis var. Sinensis, widely grown in China and Japan, is a small-leaved shrub that can withstand colder climates. This variety is mainly used for the production of green tea
The different types of tea are created through the type of processing:
Black tea: It is created through a special variant of production. The tea leaves are withered, rolled and fermented / oxidized. The most important varieties are Assam, Ceylon, Darjeeling and Keemun. It has a relatively high caffeine content, but is always below that of a cup of coffee.
Pu-erh tea: A partially fermented tea that is similar in character and in the amount of caffeine to black tea.
Oolong tea: A special variety of Camellia sinensis with larger leaves is used for the production. In contrast to other types of tea, more mature tea leaves are picked.
White tea: Minimally processed before drying and is harvested from the first tips and buds of the tea tree. It has a very mild taste and low caffeine content.
Green tea: It is not fermented or oxidized and has a mild taste. The green tea contains half as much caffeine as black tea.
What are the effects of green tea polyphenols?
After harvesting the green tea, the leaves are immediately steamed ( Japanese green teas ) or pan-roasted (Chinese green teas) to prevent the oxidation process. They are then rolled or pressed into their final shape and dried.
Roasting or steaming the green tea leaves prevents the oxidation and fermentation process by inhibiting polyphenol oxidase. This means that almost all of the active ingredients present in the fresh leaves are retained. This gives the leaves of green tea their light green color and taste, as well as their high polyphenol content.
Why is drinking green tea good for us?
The green tea plant (Camellia sinensis) contains biologically active compounds known as polyphenols. Their consumption has long been associated with health benefits. Green tea contains almost 4,000 bioactive compounds, with the polyphenols making up the largest proportion.
Polyphenols are the natural aromatic compounds that contain phenolic units and are the most abundant secondary metabolites in plants. They include:
- Phenolic acids
In recent years, nutritionists have focused on the health benefits of polyphenols. Many preclinical and clinical studies of green tea looked at the effects on human health. They suggest that polyphenols, being very potent antioxidants, could prevent various diseases associated with oxidative stress.
As antioxidants, they delay, prevent or prevent the oxidation of lipids, proteins or nucleic acids in our body. They intercept free radicals and reduce oxidative stress. Oxidative stress is related to the development and progression of various chronic degenerative diseases. This includes:
- Heart disease
- Aging process
- Infections / inflammation
- Immune system disorder
- Diabetes, rheumatism or Alzheimer’s
Green tea polyphenols have an ideal chemical structure for scavenging free radicals. Many studies suggest that polyphenols may reduce oxidative stress more than vitamins C and E or carotenoids. In addition to their antioxidant function, these compounds display a variety of biological activities that could be classified as anti-cancer, anti-inflammatory, and antimicrobial.
What did studies say about the green tea extract EGCG?
Now to the catechins: These are polyphenolic plant metabolites from the group of flavonoids, which are secondary plant substances. They belong to the flavanol group of flavonoids, which can make up up to 30% of the dry weight of tea leaves. Due to its post-harvest processing, green tea contains more catechins than other types of tea. But the catechin content also varies between the different green teas, which is influenced by growing conditions, the time of harvest or the brewing temperature of the plants.
The four main catechins found in green tea are:
- Epicatechin (EC)
- Epicatechin-3-gallate (ECG)
- Epigallocatechin (EGC)
- Epigallocatechin-3-gallate ( EGCG )
The epigallocatechin-3-gallate is the most abundant and most active Chatechin.
EGCG is a very potent antioxidant compound with proven biological activities. This includes its ability to reduce the risk of type 2 diabetes and its cardiovascular complications (12) or neurodegenerative diseases (13). The strong antioxidant activity of EGCG from green tea is due to the numerous hydroxyl groups (-OH) in its structural rings. Growth-inhibiting effects of EGCG have been shown in various animal models (1,2).
Various studies suggest an anti-tumor activity of EGCG . These include various animal studies against lung tumors (4, 5) and colon / intestinal tumors (6, 7). In contrast to animal studies with controlled experimental conditions, studies in humans showed different results. Many factors need to be considered, including the diversity of people and their lifestyles.
There have been many scientific studies regarding tea consumption and the risk of colon, lung, ovarian and breast cancer in humans with no clear conclusions. While many studies suggested reducing the risk of cancer through consumption of green tea (8, 9), many other studies did not.
Green tea and cancer: what is the current study situation?
Most of these studies with green tea came from regions with high tea consumption. The results showed that the cancer preventive activity of EGCG depends on the location of the organ and the digestive tract that is in direct contact with the tea extract. This has a concentration of EGCG that could have cancer-preventing activity.
In addition, studies show that some factors influence the stability of EGCG, such as: B. a high pH or a high temperature, which can promote its degradation. At the same time, taking EGCG along with vitamin C or minerals such as selenium or chromium increases its antioxidant capacity (10, 11).
Green tea: how are extracts extracted?
In most cases, however, the EGCG concentrations required to observe these biological effects varied. The amount of green tea consumed daily and the bioavailability of the ingredients also influence a possible therapeutic effect.
A pretty good solution to increasing the absorption of bioactive tea ingredients are dietary supplements with green tea and green tea extracts. Extraction of EGCG from green tea retains its biological activity and is a source of high quality polyphenols.
There are several methods for EGCG extraction from green tea, including water and solvent-based, microwave, or ultrasound-assisted extraction. EGCG is susceptible to light, high temperatures, and alkaline conditions. It is therefore a challenge to maintain oxidative stability and extract high quality EGCG.
Water extraction from green tea leaves therefore offers a fairly gentle way to extract the EGCG without harsh solvents. A procedure that is binding for Germany, Austria and Switzerland and complies with FDA regulations on food safety. So the “gold of Asia” can be safely won for your consumption and offers you the most valuable thing from green tea: the beneficial EGCG!
Would you like to see 8 possible benefits of EGCG in one simple infographic? Then please click here.
1. Thawonsuwan J, Kiron V, Satoh S, Panigrahi A, Verlhac V (2010). Epigallocatechin-3-gallate (EGCG) affects the antioxidant and immune defense of the rainbow trout, Oncorhynchus mykiss. Fish Physiol Biochem. 36: 687-697.
2. Higdon JV, Frei B (2003). Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions. Crit Rev Food Sci Nutr. 43: 89-143.
3. Yoshizawa S, Horiuchi T, Fujiki H, Yoshida T, Okuda T, Sugimura T (1987). Antitumor promoting activity of (-) – epigallocatechin gallate, the main constituent of “tannin” in green tea. Phytother Res. 1: 44-4.
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8. Yang CS, Maliakal P, Meng X (2002). Inhibition of carcinogenesis by tea. Annu Rev Pharmacol Toxicol. 42: 25-54.
9. Bettuzzi S, Brausi M, Rizzi F, Castagnetti G, Peracchia G, Corti A (2006). Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study. Cancer Res. 66: 1234-1240.
10. Peters CM, Green RJ, Janle EM, Ferruzzi MG (2010). Formulation with ascorbic acid and sucrose modulates catechin bioavailability from green tea. Food Res Int. 43: 95-102.
11. Giunta B, Hou H, Zhu Y, Salemi J, Ruscin A, Shytle RD, Tan J (2010). Fish oil enhances anti-amyloidogenic properties of green tea EGCG in Tg 2576 mice. Neurosci Lett. 471: 134-8.
12. Zamora-Ros R, Forouhi NG, Sharp SJ, Gonzalez CA, Buijsse B, Guevara M, Van Der Schouw YT, Amiano P, Boeing H, Bredsdorff L, et al. (2013). Dietary intakes of individual flavanols and flavonols are inversely associated with incident type 2 diabetes in European populations. J Nutr. 144: 335-343.
13. Chakrawarti L, Agrawal R, Dang S, Gupta S, Gabrani R (2016). Therapeutic effects of EGCG: a patent review. Expert Opin Ther Pat. 26: 907-16.
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