(Health Secrets Newsletter) Green tea from Asia has entered Western markets with a bang, amid claims that it can prevent and treat almost everything that ails mankind. At first it seemed too good to be true, but now we are finding out it istrue. The list of benefits from drinking green teas gets longer almost everyday.
All forms of real tea comes from the Camellia sinensis plant, and what differentiates the forms is the amount of processing they undergo. Green tea is less processed than black tea, and retains more of its healthy polypenols, especially a catechin known as epigallocatechin-3-gallate(EGCG). This catechin is credited with many of the benefits of green tea, but recent research has documented that other catechins in green tea are equally or even more potent and underwrite many of these benefits. So while supplements of EGCG extracted from green tea are readily available, the maximum benefits from green tea consumption requires drinking the tea itself or taking a supplement containing the whole leaf.
Most of the research revealing the health benefits of green tea is based on the amount of green tea typically consumed in Asian countries, which runs about 3 cups per day. (As you read this article, keep in mind that a cup of tea in Asia is small, consisting of about 3.2 ounces.) Drinking one cup will provide 20-35 mg of EGCG, along with other antioxidant flavonoids. It is interesting to note that dry green tea leaves contain a whopping 30%-40% of flavonoids by weight! The amount of caffeine in green tea is much lower that the caffeine content of black tea.
Green tea protects against death from all causes
Tea is the heathiest choice of all beverages including water, because while green tea hydrates as well as water, it also provides health promoting polyphenols. This has been documented in many studies.
Other studies have found that drinking green tea lowers the risk of death from all causes. One of these followed 40,530 adults in northeastern Japan ranging in ages from 40 to 79 for up to 11 years. In that region, 60% of the population drinks green tea, and more than half drinks at least 3 cups per day.
When compared to participants drinking less than 1 cup of green tea per day, those drinking 5 or more cups had a significantly lower risk of death from all causes, including cardiovascular disease. These results included:
23% lower risk of death from any cause
31% lower risk of death from cardiovascular disease
62% lower risk of death from stroke
12% lower risk of death from any cause
22% lower risk of death from cardiovascular disease
42% lower risk of death from stroke
Protection from cardiovascular disease
Elevation of free radicals in the arteries is a key event in many forms of cardiovascular disease. Research has shown that green tea inhibits the enzymes involved in the production of free radicals in the endothelial lining of the arteries where plaque can form, preventing the development of cardiovascular disease.
Green tea lowers the risk of atherosclerosis by lowering LDL cholesterol, triglycerides, lipid peroxidation, and fibrinogen which is a protein in the blood involved in the formation of blood clots. Green tea improves the ratio of LDL (“bad” cholesterol) to HDL (“good” cholesterol).
The mix of catechins found in green tea inhibits the activity of pancreatic lipase, the enzyme secreted by the pancreas for digestion of fats. This slows the rate at which the body breaks down fats into triglycerides, and the rise of triglyceride levels in the blood stream that occurs after meals, a significant risk factor for coronary heart disease.
Green tea normalizes blood, preventing blood clots by stopping the formation of pro-inflammatory compounds that occurs from the consumption of omega-6 fatty acids found in meats and polyunsaturated vegetable oils.
During acute cardiac events, being a drinker of green tea has special benefits. EGCG confers powerful protection to prevent the death of heart muscle cells. EGCG also speeds up the recovery of damaged heart cells. During a stoke EGCG protects brain cells and minimizes damage.
The risk of developing high blood pressure was lowered by 46% in those drinking 1/2 to 2-1/2 cups of green tea per day, and 65% among those drinking more than 2-1/2 cups per day.
Cancer depends on cell growth and proliferation. Normal brakes on cells turn off and they multiply out of control. Green tea can stop abnormal cell proliferation. Catechins in green tea turn off primary relay stations, known as tyrosine kinase receptors,through which growth factors send their messages for growth, thereby stopping cancer.
The World’s Healthiest Foodswebsite sponsored by the George Metaljan Foundation says “For cancer prevention, the evidence is so overwhelming that the Chemoprevention Branch of the National Cancer Institute has initiated a plan for developing tea compounds as cancer-chemopreventive agents in human trials.” Green tea helps to terminate cancer cells in a remarkable number of ways.
The polyphenols in green tea are powerful triggers of appropriate cell death (apoptosis), and halt the cell cycle in cancerous cells, but they leave normal cells untouched. Green tea inhibits angiogenesis, the mechanism by which cancer cells develop their own blood supply. Green tea also works at the genetic level to shut off genes in cancerous cells that spur growth, and to turn on genes that tell cancer cells to self destruct. In addition, green tea turns on genes that direct some cancer cells to return to normal.
Green tea is able to provide specialized action in specific forms of cancer. It inhibits the production of prostate-specific antigen (PSA), a marker for prostate cancer. And green tea helps prevent the spread of prostate cancer by mobilizing several molecular pathways that shut down the proliferation and spread of tumor cells.
Green tea enhances survival in women who have ovarian cancer by inducing appropriate cell death in cancerous cells by affecting a number of genes and proteins. Women drinking one cup of green tea per day had a 24% lower risk of this disease, while women drinking three cups per day cut their odds by 46%.
Polyphenols from green tea combined with inositol hexaphosphate (IP6) have recently been shown effective against pancreatic cancer, known as the most deadly form of cancer. Few other effective treatments exist for this form of cancer.
EGCG strongly inhibits telomerase activity in children with neuroectodermal brain tumors.
Green tea reduces the increased risk for colon associated with eating a high fat diet. Regular consumption of green tea has been found to cut colorectal cancer in half.
Green tea lowers risk of gallstones and biliary tract cancers. Women drinking one cup of tea each day for at least 6 months had a 44% reduced risk of getting gallbladder cancer, and a 35% reduced risk of bile duct cancer.
Green tea protects lungs against cancer even in smokers, by decreasing DNA damage and cancerous cell growth, and promoting appropriate cell death.
In those with invasive bladder cancer, green tea targets cancer cells while leaving healthy cells alone. By inducing Rho signaling, green tea causes bladder cancer cells to mature more rapidly and to adhere with each other in a process that inhibits their mobility and takes away their ability to invade.
Improved insulin sensitivity in type 2 diabetics
Population and animal studies have suggested that drinking green tea can help prevent type 2 diabetes because it improves fasting blood levels of glucose, insulin, triglycerides and free fatty acids. It increases the ability of fat cells to respond to insulin and absorb blood sugar. Rats eating a Japanese diet and fed green tea had much lower triglycerides and cholesterol.
EGCG also works on the genetic level, causing a reduction in the number of messenger RNAs that direct liver cells to produce the enzymes involved in the creation of glucose.
Green tea builds bone
Drinking green tea may significantly increase bone mineral density and prevent osteoporosis. Its catechin flavonoids provide these benefits via hormone effects known to build bone strength and/or induce apoptosis in bone-destroying cells. This action is similar to the way in which bisphosphonate drugs like Fosamax prevent bone loss, but while these potent drugs can have very nasty side effects, green tea is completely safe and offers a wealth of other health benefits.
Drinking green tea provides bone benefits similar to calcium or exercise. In a 5 year trial involving 1,500 women ages 70-85, tea drinkers had total bone mineral density (BMD) 2.8% higher than non-tea drinkers. Over the course of the study, tea drinkers lost an average of 1.6% of their total hip BMD, while non-tea drinkers lost 4%. The study included drinkers of all kinds of tea, and the results may have been even more impressive if they had included only women who consumed green tea. Black tea contains between 3-10% polyphenols compared to the 30-40% in green tea.
Green tea also supports healthy teeth by short circuiting the damaging effects of the bacteria most responsible for gum disease, P. gingivalis.
Protection of the liver
Research has shown that EGCG protects the liver against free radicals generated by exposure to toxic substances. With EGCG, free radical production and liver injury was so greatly reduced that researchers suggested green tea should be used in the treatment of liver disease.
Green tea promotes weight loss and endurance
Green tea promotes fat loss, and particularly loss of visceral fat, the fat that accumulates in the tissues lining the abdominal cavity and surrounding the intestines and organs. Visceral fat is highly associated with increased risk of type 2 diabetes.
Three major components of green tea promote fat burning: catechins, caffeine and theanine. Research has suggested these compounds promote fat loss by inhibiting production of gastric and pancreatic lipase, the enzymes that digest triglycerides and also by inhibiting fatty acid synthetase, the enzyme that synthesizes fatty acids into the form in which they can be stored in the body’s fat cells.
The ability of green tea to reduce body fat and damage to LDL cholesterol has been documented in a human trial. After 12 weeks of drinking just one bottle of green tea each day, 38 normal or overweight men in Tokyo had a significantly lower body weight, body mass density, waist circumference, body fat mass, and amount of subcutaneous fat compared to men who drank a bottle of oolong tea each day. The men drinking green tea also showed a significant drop in damage to LDL from free radicals.
Rats given green tea extract over a 10 week period increased the amount of time they could swim before becoming exhausted by as much as 24%. Catechins have a stimulating effect on the use of fatty acids by the liver and muscle cells. In muscles, the ability to burn more fat translates into a reduction in the rate at which glycogen is used, allowing for increased exercise times. The ability of green tea to help muscle cells take in and burn fatty acids is also thought to the reason why it helps weight loss.
However, drinking a single serving of green tea before exercise did nothing to improve lab rat performance. When rats were given green tea daily over a period of 10 weeks, their endurance gradually increased over that time.
Twarts Alzheimer’s and keeps the mind sharp
Green tea invokes a wide spectrum of neuroprotective cellular mechanisms, including iron chelation, scavenging of free radicals, activation of survival genes and cell signaling pathways, and regulation of mitochondrial function. (The mitochondria is the furnace of the cell in which energy is produced)
The accumulation of iron in areas of the brain and free radical damage to brain cells are believed to be the major damaging factors responsible for many neurodegenerative disorders such as Parkinson’s and Alzheimer’s. EGCG binds with iron in the brain and removes it, preventing it from contributing to the production of free radicals. EGCG also increases the activity of two major antioxidant enzymes, superoxide dismutase (SOD) and catalase. These actions also help mitigate free radical damage.
Animal studies have suggested that drinking a daily cup or two of green tea may reduce the risk of age-related degenerative brain disorders. Researchers looked at the protective effects of EGCG and another polyphenol from green tea known as epicatechin gallate on dying nerve cells. Both black and green tea extracts and catechins strongly blocked death of brain nerve cells (neurons).
When researchers exposed cultured neurons to amyloid alone, they found its effects were so toxic that the brain cells dies. But when the cell cultures receiving amyloid also received tea extracts and catechins immediately after, the neurons survived.
Polyphenols from green tea have also shown the ability to affect cell signaling pathways which are triggered by oxidative stress and are thought to play a role in neurodegenerative diseases.
Age related decline in brain function that exhibits itself as memory loss, cognitive impairment, dementia and Alzheimer’s can be helped by green tea. Researchers in Japan’s Tohoku University studied 1003 subjects over the age of 70, comparing their green tea intake and mental sharpness using a standardized evaluation scale. They found that drinking more than 2 cups a day of green tea slashed odds of cognitive impairment in both men and women by 64%! Remember, a Japanese cup of green tea contains only about 3.2 fluid ounces.
At every level of cognitive impairment, those who drank the most green tea experienced significantly less mental decline than those who consumed the least.
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