LIFE EXTENSION MAGAZINE
By Henry Jenkins
Protection from DNA Damage and More
Degenerative aging is the result of the accumulation of pathological processes inflicted on cells, tissues, and organs.1,2 By targeting each of these degenerative processes, premature aging can be slowed and life span prolonged.
Green tea protects against many age-accelerating factors, particularly DNA damage, while also promoting DNA repair. These systems work with extreme precision to identify, remove, and heal damaged DNA.3,4
A recent analysis showed that green tea polyphenols have 200 human target genes, including those involved in inflammation, cancer, diabetes, neurodegenerative, muscular, and cardiovascular disease.5
In addition, green tea supplementation has been found to significantly reduce the risk of diabetes, stroke, and depression and improve blood levels of cholesterol and glucose.6
An exciting longevity study showed that rats supplemented with epigallocatechin-3-gallate(EGCG), the most bioactive component of green tea, lived an average of 14% longer than control animals!7
In this article is a top-level review of the most current data on green tea and epigallocatechin-3-gallate that demonstrates how they combat the underlying causes of aging and disease.
Protective Mechanisms That Prolong Life Green tea (Camellia sinensis) provides powerful protection against two underlying processes that cause premature aging and disease:oxidative stress and DNA damage.3,4
Simply living on a planet that has highly reactive oxygen in the atmosphere imposes tremendous chemical stresses on virtually all molecules that come into contact with it. This results in damage to both cellular structure and function.
Similarly, all living things rely on their genetic blueprint, preserved in DNA (or sometimes RNA), to maintain healthy, renewable, functional molecules. This includes all of the structural proteins that hold us together and all of the enzymes that carry out the processes of life. DNA damage results from oxidative and other chemical stresses, from radiation, from environmental toxins, and myriad other sources. This poses a major threat to one’s ability to remain robust and healthy.
Studies in both animals and humans have now demonstrated the powerful effect of green tea on preventing, reducing, and repairing tissue damage caused by oxidative stress. Green tea enhances natural cellular protective systems, slows inflammatory responses to chemical stress, improves metabolic performance, and prevents cell death. Importantly, green tea has been shown to have these beneficial effects even during exposure to some of the most dangerous environmental contaminants, such as industrial chemicals and cigarette smoke.8-12
Green tea has equally broad-ranging effects on DNA damage and repair. For starters, it offers strong protection against a major cause of DNA damage: oxygen free radicals. But in addition to protecting against DNA damage, green tea also promotes DNA repair systems by regulating cellular stress response genes. These systems work with extreme precision to identify, remove, and heal damaged DNA.3,4
This was demonstrated in a recent human study in which green tea supplementation reduced DNA damage in white blood cells by 30% after just a single dose. It maintained that level of protection during a week of supplementation.3
In fact, a recent analysis showed that 15 polyphenols from green tea have 200 human target genes, including those involved in cancer, diabetes, neurodegenerative disease, cardiovascular disease, muscular disease, and inflammation.5 This kind of broad-spectrum, multi-targeted action is precisely what is required if one wants to seriously reduce chronic, age-related disease and significantly prolong life.
A remarkable study demonstrates this longevity impact of green tea. Healthy rats supplemented from weaning onward with epigallocatechin-3-gallate from green tea lived an average of 14%longer than control animals (105 weeks versus 92.5 weeks). They had significant reductions in oxidative stress, inflammation, and liver and kidney damage.7 In addition, two important pro-longevity genes were sharply increased in supplemented animals.
A host of promising studies has appeared in just the last few years, all of which show green tea’s ability to fight a wide spectrum of age-related disorders. Let’s examine these now.
WHAT YOU NEED TO KNOW
Green Tea Battles Age-Related Disorders
By now, most Americans know that metabolic syndrome is a prominent threat to longevity. Nearly 35% of adults and 50% of those older than 59 are known to have the condition,13 which is defined as having three or more of the following: excess abdominal fat, high blood pressure, abnormal lipid profiles, and elevated glucose.14
Having metabolic syndrome is dangerous because it raises the risk of developing heart attacks, strokes, diabetes, and cancer. In addition, it may be associated with other age-related, age-accelerating conditions including osteoporosis and neurodegenerative diseases.15-17 This makes combating metabolic syndrome a major target for efforts to slow aging and prolong life span.
This is another way that green tea can ultimately help prolong life span. Numerous studies show that green tea extracts and epigallocatechin-3-gallate can prevent and mitigate metabolic syndrome. Here is a summary of major recent findings in humans:
The greatest dangers posed by metabolic syndrome are vascular diseases like heart attack and stroke, which are today’s leading killers.27
Green tea shows promise in preventing an array of cardiovascular disorders, as we’ll see next.
Green Tea Lowers Cardiovascular Risk
Large-scale epidemiological studies show that people who regularly drink green tea are at a significantly reduced risk for heart disease and stroke.28One such study also showed that, compared with those who didn’t drink tea, men who consumed the most green tea had a 64% decrease in the risk of having coronary artery disease, the narrowing of heart blood vessels that precedes a heart attack.29
In a large meta-analysis published in the International Journal of Cardiology, researchers reviewed nine studies that included more than a quarter million individuals. They found that, compared to non-tea drinkers, those who drank one to three cups per day had a 19% reduction in risk of heart attack and a 36% reduction in stroke risk. The reduction in heart attack risk reached 32% in those who consumed more than four cups per day.30
Several interacting and complementary mechanisms account for this impressive risk reduction. Laboratory studies show, for example, that the beneficial molecules found in green tea extract called catechins improve endothelial function, which is the ability of cells lining arterial walls to modulate blood flow and pressure. It accomplishes this by increasing nitric oxide, a molecule that dilates the blood vessels and ultimately lowers blood pressure.31 Improving endothelial dysfunction is critical because it is a major precursor of atherosclerosis and resulting heart disease and stroke.
In addition, epigallocatechin-3-gallate activates natural protective systems in the arteries. This has numerous beneficial effects, including removing a major impediment to nitric oxide production, and minimizing the inflammation-induced thickening of arterial walls.32 As an added benefit, both epigallocatechin-3-gallate and L-theanine (another tea constituent) are capable of preventing blood cells from sticking to artery walls, which is another early step in the development of artery-blocking plaque.33
Recent human studies show that green tea’s ability to reduce oxidative stress has additional benefits. In one study of 40 healthy adults, 500 mg of green tea catechin given orally significantly reduced plasma oxidized LDL by 19% after four weeks. Importantly, this benefit occurred without any lifestyle modification.34
A similar study showed that using 1.5 grams of ground green tea three times daily decreased the susceptibility of LDL cholesterol to oxidation, slowing the formation of oxidized LDL by 40%.35These studies are significant because oxidized LDL is one of the triggers of arterial inflammation that contributes to the risk of plaque formation and loss of endothelial function. Reducing oxidized LDL is a proven means of reducing heart attack risk.36,37
As shown in the lab studies, reducing oxidative stress in arteries improves endothelial function and helps fight against atherosclerosis. This was verified in a very challenging group of human patients, regular smokers, whose total oxidative stress is massive. Subjects taking 580 mg of green tea catechins daily had significant increases in a measure of endothelial function by two hours after the first dose. This effect persisted for the entire two weeks of the study.28 As expected, this effect was accompanied by significant increases in nitric oxide.
Green Tea Offers Premium Neuroprotection
Loss of brain function is one of the most dreaded consequences of aging. It can arise from either chronic chemical stress and overexcitation of brain cells or acute chemical stress that occurs during and immediately after a stroke. The good news is that green tea and its polyphenols offer significant protection against both kinds of brain cell injury.
Specifically, green tea polyphenols (including catechins and epigallocatechin-3-gallate) are now being strongly examined for their potential brain-protective effects against neurodegenerative diseases such as Alzheimer’s.38
One factor that can lead to a decline in brain function is excessive mitochondrial oxidative stress. Studies show that green tea catechins help combat this by promoting more efficient mitochondrial function, thereby delaying cognitive decline.39 Epigallocatechin-3-gallate also inhibits the inflammatory response of brain immune cells to chemical stresses by inhibiting a number of key inflammatory pathways.40
Another key way green tea protects against Alzheimer’s is by its actions against beta amyloid protein. This abnormal protein accumulates into dangerous, inflammatory plaques in the brains of those with Alzheimer’s disease and contributes to cell death.38,41 In a lab study, epigallocatechin-3-gallate protected brain cells in culture from the toxic effects of beta amyloidplaque.41
And in an animal model of Alzheimer’s induced by chemical toxicity, pretreating rats with green tea polyphenols reduced the accumulation of beta amyloid plaques and reduced microscopic brain damage. It also significantly improved the acute learning and memory impairments shown in unsupplemented animals.38
Parkinson’s disease, like Alzheimer’s, is the result of chronic excessive oxidative damage and inflammation. The difference is that they occur in a particular part of the brain that controls movement.42,43 Lab studies have shown that green tea extracts and catechins can reverse those changes and improve Parkinson’s-like behavior in rats.42,43 In addition, green tea polyphenols can directly interfere with the clumping together of the toxic abnormal proteins found in the brains of animals with Parkinson’s disease.43
Ischemic stroke (the kind caused by loss of blood flow) is by far the most common form of stroke. It occurs when arteries in the brain become blocked by atherosclerotic lesions or blood clots. This results in massive oxidative stress. In rat models of ischemic stroke, green tea supplementation has been found to protect the brain in numerous ways. It raises levels of natural antioxidant enzymes, reduces inflammation, minimizes the size of the infarcted (dead) areas of the brain, and reduces the cognitive effects of the injury.44,45
Finally, green tea extracts and epigallocatechin-3-gallate are emerging as powerful allies in the fight against nerve damage in diabetes (diabetic neuropathy), a major complication that leads to disability and early death. It results from the loss of pain-sensitive neurons in the spinal cord as a consequence of high blood sugar, producing severe oxidative stress.46 Studies show that treatment with epigallocatechin-3-gallate in diabetic rats can normalize chemical stresses and reduce the extreme pain response seen in diabetic neuropathy.46
Green Tea Promotes Bone Health
Osteoporosis is a major health problem in postmenopausal women as well as in a substantial number of older men. In general, it results from excessive bone loss without sufficient new bone formation.47 Studies show that much of the lack of new bone formation is a result of excessive oxidative stresses. This makes green tea an attractive candidate for the prevention of osteoporosis and its destructive consequences.48
And in fact, studies in rat models of menopause show that green tea polyphenols do indeed suppress bone breakdown and promote new bone formation as a result of their ability to fight oxidative stress. The result is an increase in bone mineral density, which is a measure of bone health.49,50
At a deeper molecular level, green tea catechins stimulate new bone-forming cells by modulation of gene expression.47 In addition, epigallocatechin-3-gallate and green tea reduce the expression of inflammation-promoting molecules (cytokines) that contribute to bone loss.51
In humans, green tea polyphenols have been shown to reduce levels of oxidative stress in postmenopausal women. This effect was further improved by participation in Tai Chi exercises, which increase muscle strength.52 Subsequent studies demonstrated significant reductions in markers of bone loss in supplemented women as well, combined with increased muscle strength. This is a vital factor in preventing falls that can lead to fractures.53
SummaryThe body is under constant chemical and physical attack, eventually yielding, at the cellular and molecular levels, to damage that hastens aging. DNA damage and oxidative stress, caused by the very air one breathes, are prominent age-accelerating processes.
Polyphenols extracted from green tea (Camellia sinensis) are versatile and powerful phytochemicals. Their twin protection against oxidative stress and DNA damage, coupled with their ability to induce protective gene expression, makes them of profound interest in the anti-aging community.
Recent studies have shown that supplementation with green tea extract and its active compound epigallocatechin-3-gallate can limit the underlying cell and tissue damage that contributes to metabolic syndrome, cardiovascular disease and stroke, neurodegenerative diseases, and even the bone loss that causes osteoporosis.
Green tea extracts, rich in epigallocatechin-3-gallate and other green tea components, offer a convenient and reliable means of attaining comprehensive, age-decelerating protection. High potency standardized tea extracts can be obtained for less than 25 cents a day, making green teaone of the great bargains on the dietary supplement marketplace.
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