Health Benefits of Green Tea - Golden Ocean Chinese Tea

Health Benefits of Green Tea

Chinese green tea is consumed by billions of people on the planet. Green tea’s history goes back thousands of years and is attributed to the Gods or first Emperors of China. In China green tea was originally used as a medicine or a tea with medicinal qualities. Over the years green tea became viewed as just a refreshing drink. Today modern science is now proving the many health benefits of green tea. green tea. After studying the science it’s hard not to think of green tea as a preventative medicine rather than just a drink. There has been a total of 6,636 referenced research studies about the health benefits of green tea in the medical and science journals – conducted since 1971. There are at least 124 beneficial pharmacological actions that green tea is capable of conveying upon the body. The most prominent physiological action of green tea is reducing oxidative damage of cells and tissue and in turn reducing inflammation. The other physiological effects of green tea are: reduction of cancer risk, reduces obesity, reduction of heart disease risk, effective against helicobacter pylori (stomach ulcer), antibacterial, antiviral, lowers diabetes risk, protects skin against UV radiation damage, anti-ageing, relieves atopic dermatitis, helps prevent baldness, relieves stress, improves mental health (memory, attention), Parkinson’s, depression, dementia, Alzheimer’s, strengthens bone and prevent osteoporosis, protects against liver damage (alcohol, pollutants and toxins), reduces risk of kidney stones and improves dental health. This is only the main conditions studied so far. There may be other biological mechanisms of green tea that are still to be discovered in the future.

So far science has managed to find the main active compounds in green tea (and tea in general). The compounds can be broken down into two main categories – 1/ Alkaloid stimulants (caffeine, theophylline, theobromine), 2/ Antioxidants or polyphenols called flavonoids/catechins – Gallocatechin (GC), Epigallocatechin (EGC), Epicatechin (EC) and Epigallocatechin Gallate (EGCG). Green teas main health effects seem to be generated by the levels of EGCG in the tea however it also seems that EGCG works in synergy with other antioxidants and chemicals in the tea

GREEN TEA AND INFLAMMATION

Green Tea has Anti-Inflammatory Effects

The preliminary research into green tea originally discovered its antioxidant properties with its ability to reduce oxygen free radicals (oxidants). This activity has a direct relationship with regards to reducing inflammation in the body.

Antioxidants have a variety of functions, from defending against oxidation at the cellular level to protecting cells and tissue from the damaging action of free radicals. However the catechins (epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) have all proved to exhibit anti-inflammatory actions by inhibiting or regulating gene expression of pro-inflammatory proteins call NF-kB which direct genes to produces more inflammatory proteins called cytokines ( IL-1b, TNF-a, IL-6). Catechins also prevent these cytokines (if they have been produced) from binding to receptor cells to produce inflammation. White tea has the highest levels of catechins hence white tea provides the highest level of anti-inflammatory activity (1,2,3).

Polyphenols found in green tea have also been found to prevent inflammation due to UV rays (4). 

Green Tea and Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints in which pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) up-regulate the inflammatory pathways.

Green tea catechins (EGCG) have also demonstrated anti-inflammatory effects on RA and also seemed to prevent RA from progressing further (5).  The green tea catechins down-regulate NF-kB which in turn down-regulates pro-inflammatory proteins – interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) thus a reduction of inflammation.

Green Tea, Cancer, Heart disease and Atherosclerosis

Green Tea – Anticancer Effects and Cancer Prevention

Oxidative damage to the cells and tissue can be the catalyst for cancer (6). Considering that green tea antioxidants/polyphenols reduce oxidative damage then, vis-a-vis, green tea should lower the risk of cancer by reducing oxidative cell damage.

Apart from just protecting against oxidative damage, the mechanism of action where by green tea inhibits or stops cancer growth and metastasis is via the DNA and RNA and signalling proteins (7).

To date, most of the studies evaluating the effects of tea on lung cancer have been focused on green tea. For instance, ample preclinical studies have shown that green tea extract (GTE) induces apoptosis in a variety of cancer cell types including colorectal, breast, endometrial, skin, brain, gastrointestinal, prostate, and leukemic cancer (8,9,10,11). 

Breast cancer: A meta-analysis (study that combines many studies together) of populations studies found that women who consumed the most green tea had a 22% lower breast cancer risk. breast cancer is the most common cancer in women (12).

Prostate cancer:  Another population study in Japan (2008) discovered that men drinking green tea had a 48% lower prostate cancer risk of developing. Prostate cancer is the most common cancer in men (13).

Colorectal cancer: A study of 69,710 Chinese women found that women who consumed green tea had a 57% reduced risk of colorectal cancer (14).

Multiple other observational studies show that green tea drinkers are significantly less likely to get various types of cancer (15,16,17).

Green Tea and Mental Health

Green Tea, Anxiety, Attention, Improved Memory and Intelligence

Green tea has been found to up-regulate N-acetyl aspartate (18), which can help with memory and intelligence.

The stimulants such as caffeine, theophylline and theobromine work together with L-theanine with the net result being improved brain function. Even without the actions of theophylline and theobromine the quantity of caffeine in green tea is enough to improve reaction time and memory as well as increase the levels of dopamine and norepinephrine in the brain (19). L-theanine can induce greater attention and focus by facilitating Alpha electroencephalographic wave lenths (8-14 Hz) in the brains parieto-occipital area (20).

However apart from the effect  of stimulants the polyphenol EGCG and L-theanine both increase memory and attention in people with mild brain damage (21). L-theanine can also modulate the effects of anxiety thus have a calming effect upon people with anxiety (22). The polyphenol EGCG  in green tea can refresh and relax your brain (23).

Green tea in general has been shown to improve cognitive functions such as mood, alertness, calmness, and contentedness, attentional switching accuracy even within the first 1-2 hours (24).

The antioxidant polyphenols (EGCG) have been found to stimulate the generation of neurological cells within the hippocampus which is thought to control learning and memory (25).

Dementia, Alzheimer’s, Parkinson’s and Cognitive Decline

Regular drinking of green teas in general has been shown to help ageing by maintaining brain functions and preventing or slowing cognitive decline (26, 27).

There has been a significant amount of research with regards to Alzheimer’s as well as cognitive function of the brain. A large  population study (Singapore Longitudinal Aging Study) showed that consumption of a daily cup of tea (green, oolong, black and pu’er tea) for people over 55 years of age reduces cognitive decline by over 50% and people with a genetic predisposition to Alzheimer’s reduced their risk by 86% (28, 29, 30).

The polyphenols found in green tea protects neurons in the brain and thus protecting against dementia, Alzheimer’s, and Parkinson’s disease (31, 32, 33, 34).

Green tea also reduced depressive symptoms by activating the part of the brain associated with reward learning (35).

Green Tea and Multiple Sclerosis

The green tea polyphenols (EGCG) have been found to be neuro-protective agent thus protect mitochndria in brain cells from oxidative stress and premature cell death (36).

Green Tea, Weight Loss and Reducing  Obesity

There have been many studies with regards to green teas effect upon weight loss and obesity. The antioxidant (catechins – EGCG) seem to be the prime fat burning  agent within green tea however green teas energy expenditure and fat metabolising (burning) effects are increased in the presence of caffeine (37). Green tea contains caffeine, theophylline and theobromine which all up regulate thermogenesis (helps your body produce more heat) to increase the body’s metabolism – the rate at which your body burns energy (38). Green tea also seems to target specific fat cells as studies have shown that it decreases abdominal body fat as well as total body fact (39, 40).

A 12 week randomized controlled study of 240 Japanese men and women found that green tea decreased body fat percentage, body weight, waist circumference and abdominal fat (41). The fact that green tea increases metabolism (42) is a bonus in the weight loss process however green tea works on many other levels besides just increasing metabolism

Green tea has shown to suppress the appetite and lead to less energy consumption (43). Green tea can also help reduce obesity by reducing fat and starch/glucose digestion and absorption, and blocking fat creation, increasing metabolism (fat burning) as well as reducing inflammation – which is also implicated in obesity (44, 45).  It has also been discovered that the catechins, in Green tea could inhibit the activities of some digestive enzymes (a-glucosidase and invertase) to reduce absorption of glucose and sucrose (46). 

Another mechanism of weight loss that green tea provides is its ability to down regulate an enzyme (Catechol-O-methyltransferase) that breaks down norepinephrine (noradrenaline). Noradrenaline is a chemical/hormone that increases fat burning hence maintaining high levels of noradrenaline is another benefit when trying to loss weight (47). Interestingly, decaffeinated green tea extract did not have the same weigh loss effect as decaffeinated green tea hence the synergistic nature of green tea and caffeine should be considered. It did however reduce fasting insulin levels (48).

Added to all these mechanisms green tea can also increase exercise endurance hence a person can exercise longer expending more energy thus burn more fat (49).

Green Tea Polyphenols Reduce Heart Disease Risk

Cardiovascular disease is the largest cause of death world wide (50).

Studies have shown that green tea  can help lower risk factors such as LDL cholesterol (51).

The polyphenols in green tea have demonstrated a role in protecting Low Density Lipids (LDL) from oxidisation. It is the  oxidised LDL that has been implicated as a risk factor in heart disease an atherosclerosis (52, 53, 54).

Green tea also lowers blood pressure by increasing blood flow in the body (R).

The polyphenols (catechins) in green tea have been associated with lower levels of heart disease and stroke (55, 56, 57, 58). Given the beneficial effects on risk factors, it is not surprising to see that green tea drinkers have up to a 31% lower risk of cardiovascular disease (59, 60, 61).

A 2001 study published in the “American Journal of Epidemiology.” demonstrated a positive relationship between 3 cups of tea per day and an 11% drop in coronary heart disease (62).

Components such as catechins help to dilate blood vessels which allows for a reduction in blood pressure and better blood flow throughout the body (63).

Green Tea Lowers Risk of Diabetes

Obesity and Type II diabetes over the last decade has increased to epidemic levels and now affects approximately  300 million people worldwide.

The symptoms of Type II Diabetes are elevated blood sugar levels because of cellular insulin resistance. The cells have become resistant to insulin because they are overwhelmed by too much free glucose in the blood.

Catechins in green tea can help reduce the risk of Type II Diabetes by improving insulin sensitivity (64). Once the cells are no longer resistant to insulin then fasting blood glucose levels return to normal (65).

One Japanese study of 17,413 people (6727 men and 10,686 women) 40 to 65 years of age, found those who drank the most green tea had a 42% lower risk of developing type II diabetes (66).

A large scale meta-analysis of sixteen cohort studies from fifteen articles that reported 37,445 cases of diabetes among 545,517 participants. This study showed that an increased consumption of 2 cups of tea per day was found to be associated with a 4.6% reduced risk of Type II Diabetes (67).

A systematic review of 7 studies totalling 286,701 individuals, showed that green tea and caffeine drinkers had an 18% lower risk of becoming diabetic (68).

Green Tea Fights Against Bacterial Infections

The polyphenols in green teaepigallocatechin gallate (EGCG) and epicatechin gallate (ECG), have shown to be antiviral and antibacterial, both Gram-positive and Gram-negative bacterial species with moderate effect (69, 70). Green tea can reduce bacteria spores in the body (71). 

Green teas antibacterial effects have been demonstrated against  a number of microorganisms including Staphylococcus aureus, Vibrio cholerae, Escherichia coli, Shigella spp., Salmonella spp., Bacillus spp., Klebsiella spp. and Pseudomonas aeruginosa (72, 73).

Green tea has demonstarted efficay agaisnt the influenza virus, as well as against the Herpes simplex virus, tobacco mosaic virus, enterovirus, rotavirus, Epstein Barr virus, HIV virus as well as antifungal with regards to Candida albicans, Trichophyton mentagrophytes, and Trichophyton rubrum (74). 

The EGCG in green tea damages the bacterial membrane but also inhibits the bacteria from attaching to oral cellular surfaces thus rendering the bacteria ineffective (75).

Green tea has also been used in mouthwash to effectively reduce plaque and gingivitis (76).

EGCG Improves Liver Health

Liver health has shown improvement in people with non-alcoholic fatty liver. People who consumed 700 ml of green tea (containing >1 g polyphenol/catechin/EGCG) per day over 12 weeks  improved liver fat content and inflammation by reducing oxidative stress (77).

Green Tea Improve and Protects Skin

The EGCG content in green tea has been demonstrated (similar to white tea) to have anti-wrinkle properties (78).

Green Tea EGCG Prevents Baldness

The EGCG  polyphenols in green tea can stimulate human hair growth and help prevent baldness (79).

Green Tea  Promotes Dental Health

Green tea polyphenols (EGCG) helps oral defence mechanisms and can prevent gingivitis. It provides additional protection against oxidative stress in the mouth (80).

The green tea polyphenols also helps enhance the bond strength of dental adhesives (81).

Green tea has also been used in mouthwash to effectively reduce plaque and gingivitis (82).

Green Tea Prevents Osteoporosis

Green tea catechins (EGCG) stimulates osteoclast and osteoblast growth in bone cells. The green tea catechins (EGCG) can be used as a pro-osteogenic treatment for the stem-cell-based therapy of osteoporosis (83).

Green Tea Can Help You Live Longer

Green tea polyphenols (catechins) have been found to protect telomeres, in cardiac cells, from oxidative damage (84). Longer telomeres protect the integrity of DNA in the replication process thus reducing our disease risks while also slowing biological ageing (85). 

Green tea polyphenols (catechins) also demonstrate the ability to affect various epigenetic mechanisms (genetic expression) that are linked with lower disease risk and longer life (86).

 

 

 

 

 

References:

 

(7) Ahmad, N., Feyes, D.K., Nieminen, A.L., Agarwal, R., Mukhtar, H., 1997. Green tea constituent epigallocatechin-3-gallate and induction of apoptosis and cell cycle arrest in human carcinoma cells. J. Natl. Cancer Inst. 89, 1881e1886.

(8) Paschka, A.G., Butler, R., Young, C.Y., 1998. Induction of apoptosis in prostate cancer cell lines by the green tea component, ()-epigallocatechin-3-gallate. Cancer Lett. 130, 1e7.

(9) Yang, G.Y., Liao, J., Kim, K., Yurkow, E.J., Yang, C.S., 1998. Inhibition of growth and induction of apoptosis in human cancer cell lines by tea polyphenols. Carcinogenesis 19, 611e616.

 

 

 

 

 

 

 

 

 

 

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