Last Updated on 11/24/2020 by Desmond
When we talk about tea, we often heard the word “Tea Polyphenols,” which is usually used for advertising. No matter the loose-leaves or the supermarket’s tea beverage, even some skin cares, they all advocated that Tea Polyphenols are an excellent benefit for people.
In most people’s impressions, tea polyphenols are often associated with weight loss, anti-cancer, and other benefits. It’s also a unique nutrition fact of tea beverages.
What Are Tea Polyphenols
Tea polyphenols are not single. It means the total polyphenols substance in tea.
And they are the main ingredients which bring significant benefits from tea.
Among them, the content of flavanols is the highest, up to 70% of tea polyphenols.
According to the chemical structure, they can divide into four:
- Epigallocatechin Gallate (EGCG)
- Epigallocatechin (EGC)
- Epicatechin Gallate (ECG)
- Epicatechin (EC)
All these substances are totally called Catechins, and they play an essential role in the beneficial effect.
In addition to catechins, anthocyanins and phenolic acids are also components of tea polyphenols.
Due to the different processing of tea, the main components of tea polyphenols are also various.
Take black tea for an example. Because it has been completed fermentation, about 75% Catechins oxidized and transformed, then re-polymerization into other flavonoids substances such as theaflavin, flavonols, and phenolic acids.
Tea polyphenols can not only bring benefits to human health but also influence the quality of tea.
How Tea Polyphenols Influences Tea Quality
During the tea processing, by the growth of tea fermentation degree, the Catechins will turn into the flavonoids such as theaflavin, thearubigins, and theabrownin. And the color of the leaves become darker at the same time.
That’s why when processing green tea, leaves must be fixated first. A high temperature will destroy the activity of polyphenol oxidase and keep the leaves green.
Sometimes you may found that the green tea infusion will turn yellow after place for minutes. It’s the result of the tea polyphenol oxidation.
And to high-fermented tea such as black tea and dark tea, most of the tea polyphenol in them have been transformed, so the color of tea also darker than the low-fermented tea.
Tea polyphenols taste astringent itself, but why most of the tea does not taste like that?
Because in addition to tea polyphenols, there are amino acids in the tea that will bring umami, sugar for sweetness, and caffeine for bitterness.
The ratio of tea polyphenols to other flavoring substances determines the flavor of the tea.
The non-fermented and low-fermented tea kept more natural tea polyphenols, so they taste more bitter and astringent.
After fermentation, tea polyphenols are transformed and produced many aromatic lipids, makes the flavor layering. Oolong and Pu-erh tea lovers may have a deep feeling about that.
What Is Tea Polyphenols Good For
Tea is loved for its unique flavor and excellent benefits.
In recent years, scientists have been studying polyphenols extracted from tea in hopes of finding the solution against diseases.
As the main nutrient ingredient of tea, tea polyphenols have been suggested will bring many benefits to the human body.
The right amount of radicals helps maintain physiological balance. Still, a few excessive peroxy radicals will harmful to human bodies because of the oxidation.
Scavenging peroxy radicals must start with antioxidants.
Catechins are naturally powerful antioxidants.
Clinical trials showed that human plasma’s antioxidant capacity significantly improved within 1-2 hours after having tea.
Tea has higher antioxidant activity against peroxy radicals than vegetables (such as garlic, spinach, and brussels sprouts.) A balanced tea diet can improve the body’s overall antioxidant status and protect it from oxidative damage.
Tea polyphenols have effects on burning fat and reducing lipid accumulation.
Experiments suggested that EGCG can improve the oxidation of liver fatty acids, thus reducing appetite. And by inhibiting the activity of digestive enzymes in the gastrointestinal tract, the absorption of carbohydrates is reduced.
Besides, EGCG can promote lipid metabolism and reduce cholesterol content in the blood and the liver through caffeine’s synergistic effect.
A long-term tea diet may help with losing weight and may have a good effect on the treatment of obesity.
Most cancers are still incurable until this time, so prevention and slow disease progression are still the primary means of anti-cancer.
Scientists have investigated the anti-cancer effects of tea polyphenols on the following cancers, hope to found an effective treatment:
- Skin Cancer
- Lung Cancer
- Liver Cancer
- Pancreatic Cancer
- Bladder Cancer
- Gastrointestinal Tract Cancer
- Breast Cancer
- Prostate Cancer
Most of the researchers compared people who consume tea consistently with those who did not. The data showed that cancer risk decreased with tea consumption, frequency, and duration time growth.
The research also confirmed that EGCG could effectively induce apoptosis and cell cycle arrest but not affect the healthy cells.
Many studies have provided evidence of the potential of tea polyphenols to anti-cancer. However, their therapeutic effects on cancer are still at the research stage.
Although having tea can not cure cancer, a healthy tea diet can go a long way toward preventing the disease’s occurrence and deterioration.
Type Ⅱ diabetes is often associated with obesity. Tea polyphenols, especially the EGCG, are thought to have diabetes auxiliary treatment function due to their anti-obesity effect.
Research indicates that tea polyphenols do have a significant function in the auxiliary treatment of diabetes. Still, its effect does not come by lowering blood sugar.
It may come from the tea polyphenols antioxidant benefit. By enhancing the scavenging on active peroxy radical and hydroxyl radical, regulate lipid metabolism, and anti-lipid peroxidation effect to delay the progression of diabetes.
Although tea polyphenols cannot treat diabetes, a tea diet can play an excellent role in the management and auxiliary treatment of diabetes.
CVD(Cardiovascular Disease) Prevention
Medical researches found that long-term consumption of tea can effectively prevent cardiovascular diseases.
Oxygen radicals can cause lipid peroxidation and lead to atherosclerosis, which is the leading factor of CVD causes.
Besides reducing cholesterol in serum, tea polyphenols can increase HDL-C (high-density lipoprotein cholesterol) content, clear the accumulated cholesterol in the arterial wall, and inhibit LDL-C(low-density lipoprotein cholesterin) uptake by cells. It’s conducive to the prevention and alleviation of atherosclerosis.
Tea polyphenols are also rich in flavonoids. In addition to preventing infections, they are the best blood-vessel cleaners, preventing cholesterol oxidation and platelet clotting, thereby reducing heart disease stroke risk.
We usually learn from the “Daily Life Tips” that gargling with tea is an effective treatment for oral inflammation.
In some folk remedies, people apply the tea leaves juice on the skin wound to prevent inflammatory.
The research found that tea polyphenols’ anti-inflammatory mechanism inhibits the transcriptional activity of NF-kB and the TLRs signaling pathway, combining with its antioxidant and bacteriostatic function, to restrain the occurrence of inflammation and achieve the result of treating inflammation.
The EGCG of tea polyphenols plays a key role.
EGCG has great against general inflammation, such as nephritis, stomatitis, dermatitis, intestinal inflammation, and osteoarthritis.
And due to the antioxidant properties of EGCG, it also plays an essential role in preventing myocarditis.
Antibacterial and Antiviral
Studies found that tea polyphenols had significant inhibitory or even killing pathogenic bacteria such as Bacillus botulinum, Enteritis vibrio, Staphylococcus aureus, Klebsiella capsulatus, Bacillus cereus, Shigella bacteria, Pertussis bacteria, and Vibrio cholera.
The primary mechanism is to inhibit bacterial cells’ growth and development and even directly destroy the bacterial cell structure.
Tea polyphenols also have antiviral effects.
Tea pigments may prevent viruses’ adsorption on cells, thus inhibiting cells’ infection by influenza virus A and influenza virus B.
Notably, the study also found that flavonoids, including EGCG and ECG, interfere with the reproduction of HIV-1 by inhibiting the activity of HIV-1 reverse transcriptase and destroying virions.
The antioxidant effect of tea polyphenols can reduce the damage of radicals to the biological cell membrane and maintain the cell membrane’s stability, which is believed to play an anti-aging effect.
Experiments on laboratory mice with water extracts from various tea types have shown that polyphenols such as EGCG, theaflavin, and thearubigins significantly improve skin wrinkles and fighting skin aging.
Although different types of tea are processed differently, there is no significant difference in their ability to improve aging skin.
The scientists also studied tea polyphenols’ role in treating Alzheimer’s Disease(AD), a disease commonly occurring in older people.
There is substantial epidemiological evidence that tea consumption is associated with a lower risk of AD and other neurodegenerative diseases.
In a long-term clinical study of people in areas where tea consumption was frequent, the researchers found that those who consumed tea had a lower risk of AD or cognitive impairment. It may benefit from the powerful antioxidant and anti-inflammatory properties of catechins.
Which Type Of Tea Contains The Most Tea Polyphenols
Like the caffeine content in tea, the polyphenols content also depends on the leaf-picking and processing.
Fresh Tea Leaves
In the fresh leaves, catechins are the main ingredients of tea polyphenols. And its content mainly depends on the following conditions:
- New branched leaves contain more polyphenols than those in the old one;
- Tender shoots contain more polyphenols than older leaves;
- A region with high-temperature, long-time sunshine can help the Camellia Sinensis produces more tea polyphenols;
- Polyphenols in the leaves of different types of Camellia Sinensis also vary, the large-leaf typically getting more;
The Processing Influence
Due to the different processing of each tea type, tea polyphenols’ ingredients in fresh tea leaves will also change during processing.
Especially after fermentation, most catechins transform into flavonoids such as theaflavin and thearubigins.
But these substances have still belonged to the components of tea polyphenols, and their benefits are not that different from catechins.
If only talk about the catechin, its content will decrease with the increase of fermentation degree. So in the general case from more to less is:
Green Tea > White Tea > Yellow Tea > Oolong Tea > Black Tea > Dark Tea.
To be sure, all true teas contain tea polyphenols. Develop a habit of tea drinking can bring lots of benefits to human bodies. But it can’t instead of the medical treatment, never believe that drinking tea alone can cure disease.
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