Life Extension Magazine

Life Extension Magazine January 2005

Cover Story

The Lancet Reports Extremely Positive Data on Green Tea

By Stephen Laifer

Protecting Aging Brains

Researchers believe that green tea may slow the effects of normal aging and its associated brain regression. A 2004 study investigated the effect of long-term green tea catechin intake on aging and oxidative damage, using aged mice with cerebral atrophy and cognitive dysfunction. Catechin intake was shown to effectively suppress further atrophy and cognitive dysfunction,23 strongly suggesting that green tea can at least partially improve the negative functional alterations that occur naturally in aging brains.

Another recent clinical trial found that green tea also offers protection against brain-deteriorative functions typically associated with stroke. As noted earlier, green tea catechins have potent antioxidant properties, protecting the body from atherosclerosis, a trigger of stroke. In this recent trial, catechins were further shown to reduce both the area and volume of damage to the brain following a stroke.24 According to the research-ers, daily intake of green tea catechins adds a measurable level of protection to the brain, helping shield it from “irreversible damage due to cerebral ischemia [stroke] and consequent neurological deficits.”24

The neurodegeneration that occurs in Parkinson’s disease, Alzheimer’s disease, and other neurodegenerative disorders is believed to involve a complex set of toxic reactions, including inflammation, neurotoxicity, increases in iron and nitric oxide, and depletion of antioxidants. These factors, among others, all lead to the breakdown and eventual failure of neurons. This has led to the current notion that drugs directed against a single target may be ineffective, while a drug or drug combination that attacks the condition in a variety of ways may be efficacious in treating neurodegenerative disorders.25

Green tea catechin polyphenols, known to be effective scavengers of free radicals, are believed to play a role in various cellular mechanisms related to neuroprotective activity. Researchers increasingly suspect catechins may be deeply involved in the activation of survival genes and in cell signaling pathways, as well as in the regulation of healthy cellular metabolism. As a result, catechins are receiving significant attention as therapeutic agents for the treatment of neurodegenerative diseases involving brain regression.25

Healthy Blood Sugar Levels

Green tea may help to normalize and maintain healthy blood sugar levels. Epidemiological data suggest that green tea consumption prevents type II diabetes.26 In healthy human volunteers, green tea promoted healthy glucose metabolism, as determined by oral glucose tolerance tests.26 Green tea also lowered blood glucose levels in diabetic mice without affecting serum insulin levels.26 Green tea therefore appears to have anti-hyperglycemic effects. Green tea may be a helpful agent in preventing type II diabetes and in promoting healthy glucose metabolism.

TOPICAL APPLICATION OF GREEN TEA ALSO SHOWS BENEFITS

The naturally occurring polyphenols in a cup of green tea have been shown to provide protection against a variety of potentially deadly cancers. New studies also show that topical application of green tea supplements can provide similarly powerful anti-cancer defenses. In particular, green tea can safeguard the skin against the damage caused by harmful ultraviolet rays, a cause of skin cancer, photoaging, and inflammation.

A study published in the journal Nutrition and Cancer examined the effects of topical application of the green tea polyphenol epigallocatechin-3 gallate (EGCG) in preventing skin tumors in mice exposed to ultraviolet radiation. Mice were treated with varying amounts of EGCG before ultraviolet treatments and throughout the experiment. The researchers found that topical administration of purified EGCG significantly reduced the induction of skin tumors by ultraviolet radiation.29 Oral administration of EGCG did not reduce skin tumor incidence in this study.29

In another study in mice, topical application of green tea polyphenols was shown to prevent the initiation, promotion, and progression of skin tumors. Green tea extract also caused a partial regression of established skin papillomas in mice. Through offering a chemoprotective effect against all the stages of carcinogenesis, the topical application of green tea appears to offer significant protection to the skin.30

Human studies also demonstrate the benefits of applying green tea topically. In a study conducted at Case Western Reserve University, topical application of EGCG to human skin produced several beneficial effects. When applied before ultraviolet exposure, EGCG significantly blocked UVB-induced infiltration of leukocytes, a major cause of the generation of reactive oxygen species. The EGCG application also reduced redness in the skin related to UVB exposure. Skin that was pretreated with EGCG demonstrated lower levels of inflammatory prostaglandin metabolites than skin that was not treated. These prostaglandins are known to play a critical role in the generation of free radicals and the promotion of skin tumors. The study researchers concluded that EGCG from green tea extract may be useful as a topical agent for protecting against UVB-induced carcinogenesis, photoaging, and inflammatory skin conditions.31

These findings indicate that green tea offers a wealth of protective benefits, not only as a health-promoting beverage, but also as a topical skin application. Topical application of green tea polyphenols can provide local antioxidant protection, helping to protect against damaging effects of ultraviolet radiation such as skin cancer and photoaging. Abundant use of green tea, both internally and topically, may thus provide protection from topical and visceral cancers, heart disease, and signs of aging.

Relief from Arthritis

Scientists believe that the antioxidants in green tea may also fight inflammation and help prevent arthritis.

Ongoing research at Case West-ern Reserve University suggests that green tea supplementation can postpone the beginning—and decrease the severity—of at least one type of arthritis.27 In this study, mice that were fed green tea polyphenols were significantly less susceptible to the development of collagen-induced arthritis, which is similar to rheumatoid arthritis in humans. Researchers noted that the arthritic mice that received the polyphenols had later onset of arthritis and developed less severe forms of the disease. The animals receiving green tea also showed a marked decrease in inflammatory mediators, including cylcooxygenase-2 and tumor necrosis factor-alpha.

Another study examined the effects of green tea catechins on human and bovine cartilage in vitro. Green tea catechins were found to inhibit the breakdown of proteoglycan and type II cartilage, which are components of healthy joint tissue. The study authors concluded, “green tea catechins are chondroprotective and consumption of green tea may be prophylactic for arthritis and may benefit the arthritis patient by reducing inflammation and slowing cartilage breakdown.”28

Green tea is an ancient beverage with a bright future of applications in preventing disease and promoting health. A powerful source of antioxidants, green tea may help to prevent cancer, protect the cardiovascular system, promote healthy blood sugar levels, and alleviate the neurological effects of aging. Green tea is thus a safe and effective natural remedy for promoting a long and healthy life.

References

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