Green tea, like all teas, comes from the plant Camellia sinensis. The uniqueness of green tea is a result of how it is processed. Green tea is one of the least processed teas. It is unfermented and instead is briefly steamed to inactive enzymes and preserve nutrients. The leaves are then dried with hot air.
The chemical constituent of green tea contribute to its health benefits. Green tea contains caffeine, theanine and polyphenols. The maximum caffeine content found in green te leaves is 5 %. Caffeine is commonly known for its stimulant and diurettic effects. Green tea contains many free amino acids found in green tea and is commonly recognised for its positive effect on brain health. The major class of polyphenols found in green tea are called catechins. Catechins derivatives such as catechin, gallocatechin, epicatechin, epicatechin gallate, gallocatechin gallate and epigallocatechin gallate are known for their potential health benefits. The health benefits of green tea are as follows :
1. Heart Health
Hearth health is one of the highest health concerns among consumers for good reasons. Cardiovascular disease is the number one killer in developed countries. Green tea addresses heart health in many ways.
2. Coronary Heart Disease
Gree tea catechins inhibits enzymes involved in free radical formation in endothalia lining of arteries. These free radicals contribute to cardiovascular disease. Japanese researchers found that people drinking more than five cups of green tea daily are 16 % less likely to suffer from coronary disease.
3. Blood Clots
Green tea catechin helps prevent the formation of pro-inflamatory compounds derived from omega-6 fatty acids. These pro-inflamatory compounds cause platelets to clump together and form clots.
4. Acute Cardiovascular Disease
Epigallocatechin gallate can help prevent the death of heart musle cells following ischemia. Ischemia is the restriction of blood supply that causes oxidative damage to the heart. Epigallocatechin gallate blocks the activation of inflammation related compunds that ultimately result in the death of heart cells.
Green tea catechins help breakdown cholesterol. They can also help eliminate cholesterol in the body by excretions in the stool.
6. Blood Pressure and Hypertension
Epidemiological studies show a 65 % reduction in the risk of developing high blood pressure among those consuming more than 2.5 cups od green tea per day.
7. Prostate Cancer
Epigallocatechin gallate significantly inhibits production of prostate specific antigen ( PSA ). PSA is a marker for prostate cancer risk. Polyphenols in green tea also prevent the spread for prostate cancer by mobilising several molecular pathways that shut down the proliferation of tumour cells.
8. Ovarian Cancer
Studies show that women with ovarian cancer who consumed more than one cup of green tea daily had a 56 % lower risk of death. Epigallocatchin gallate suppresses the growth ofovarian cancer cells. It has also been shown to induce apoptosis by affecting various genes and proteins needed by cancer cells to live and grow.
9. Lung Cancer
Green te may help prevent lung cancer. Drinking green tea has been shown to decrease DNA damage from smoking cigarettes. It also inhibits cancer cell growth and increases cellular trigger for apoptosis in abnormal cells.
10. Skin Cancer
Consumption of green tea has been shown to reduce the effect of radiation and chemically induced skin cancer. It prevents free radical formation when exposed to excessive light. In one study, green tea was applied topically to demonstrate the prevention of sunburn.
11. Liver Health
Epigallocatechin gallate protects the liver againts free radical damage from toxic chemical solvents. The metabolism of alcohol produces free radicals. This can result in the depletion of antioxidants in the liver and subsequent liver damage.
12. Fat Loss
Green te promotes the loss of visceral fat. This is fat in the tissue lining of the abdominal cavity and the surrounding internal organs. It is typically associated with the ‘apple’ body shape. Visceral fat can lead to an increased risk of metabolic syndrome and type 2 diabetes.
Catechins, caffeine and theanine found in green tea promote fat loss by blocking gastric and pancreatic liase and fatty acid synthetase. Lipase are enzymes that break down triglycerides and synthetase- the enzyme breaks the fatty acids down so they can be stored in the body’s fat cells.
13. Brain Health
Neurodegenerative diseases such as Parkinson and Alzheimer’s are the result of free radicals and increased iron chelation. This depletes the brain of its protective antioxidants. Green tea catechins have a wide spectrum of neuroprotective cellular mechanism such as iron chelation, scavenging free radicals, regulation of mitochondrial function and activation of survival genes and cell signalling pathways.
Epigallocatechin gallate is a powerful antioxidant and is 20 times stronger than vitamin E in protecting essential brain lipids. It acts as an iron chelator in the brain. Preventing iron from contributing to the production of free radicals. Epigallocatechin gallate also increases the activity of superoxide dismutase and catalase, antioxidant enzymes that help decrease free radical damage. Polyphenols from green tea affect the cell signalling pathways in the brain. They inhibit apoptosis of brain cells initiated by free radical and play an essential role in the regulation of cell survival.
Green tea is safe to consume. Studies done in rats showed no toxic effects and no mutagenecity, hematological or biochemical abnormalities. There is some concern with the potential interaction of green tea with blood thinning drugs when consumed in ammounts grater than one gallon per day. Green tea may also bind nonheme iron, inhibiting its intestinal absorption. There are no known averdoses of green tea. Recommended levels are up to five cups per day. This equates to the level of 300 mg-400 mg catechins per day and 150 mg-200 mg epigallocatechin gallate.
Summarized from the paper of Assistant Prof R Shalini and Assistant Prof Srivastava,
Yogyakarta, October 2012