Anti-Aging
The sun causes skin to age by altering connective tissue. Specifically, exposure to UV light leads to lipid, enzyme and oxygen free radical (OFR) formation. All of these factors can damage the cell structure of connective tissue in the skin. Natural skin aging is attributed to decreased skin elasticity as we get older.
Catechins are polyphenols in green tea (Camellia sinensis) that are effective against damage to collagen and elastin in skin cells. Collagen comprises some 80% of the content of skin and is responsible for maintaining the structural stability of the skin. Elastin content in skin ranges between 2 and 4% and is responsible for the elasticity of skin.1
The catechin epigallocatechin gallate (EGCG) and other catechins in green tea inhibit collagenase and elastase.2 These enzymes are the active factors that break down the proteins of collagen and elastin in skin. The characteristic signs of aging; wrinkles, changes in pigmentation and changes in skin thickness are the results of these enzymes.
In a study of anti-aging properties of extracts from 21 plants, Tamsyn and colleagues found promising results for the use of green tea to slow the telltale signs of aging.1 Athough they did not find green tea extracts (GTE) to exhibit significant anti-elastase effects (10% reduction), GTE reduced collagenase activity by about 47%. In comparison, white tea extracts showed 89% collagenase inhibition and 87% elastase inhibition. When antioxidative power of plant extracts was tested with a superoxide dismutase (SOD) assay, white tea produced an 88% reduction of oxygen radicals and green tea resulted in an 86% reduction. When the SOD enzymes work on free radicals the end products are oxygen molecules (O2) and hydrogen peroxide (H2 O2).
Protection Against Damage from UV Light
EGCG is the catechin in green tea present in the highest concentration and that is the most promising as a chemopreventative agent for the treatment of cancer. Various studies have led to the common knowledge that exposure to UV light can cause melanoma and non-melanoma skin cancers.
A 2009 study has shown that both green and white tea extracts have protective qualities from UV sun damage to human skin.4 Skin samples from study participants were treated with tea extracts and then exposed to UV light. As compared to non-treated control skin, both tea extract treatments prevented the characteristic inflammation and redness associated with sun damage. Scientists verified that the protection was not related to sunscreen effects because a test of the sun protection factor (SPF) determined an SPF of 1. More human trials are needed, but it seems that white or green tea extracts may be topically applied along with sunscreen to prevent the symptoms of UV damage on skin.
Scientists have yet to pinpoint definitive dosages and formulations of green tea components for oral or topical preparations to stop of reverse skin aging and damage from the sun. However, new findings are published nearly monthly in the scientific journals as scientists learn more about the mechanisms of skin aging, damage and repair and actions of green tea on cellular processes. Pharmaceutical preparations are also being developed and tested and perhaps soon they will be on the market.
1Anti-collagenase, anti-elastase and anti-oxidant activities of extracts from 21 plants.
Tamsyn, SA; Thring, PH and Declan P Naughton. BMC Complement Altern Med. 2009. 9:27.
2Inhibition effects of (+)-catechin-aldehyde polycondensates on proteinases causing proteolytic degradation of extracellular matrix. Kim, Y; Uyama, H and Kobayashi, S. Biochem Biophys Res Commun. 2004. 320:256–261.
3Skin photoprotection by green tea: antioxidant and immunomodulatory effects. Katiyar SK. Curr Drug Targets Immune Endocr Metabol Disord. 2003 Sep;3(3):234-42.
4Topical application of green and white tea extracts provides protection from solar-simulated ultraviolet light in human skin. Camouse MM, Domingo DS, Swain FR, Conrad EP, Matsui MS, Maes D, Declercq L, Cooper KD, Stevens SR, Baron ED. Exp Dermatol. 2009. 18(6):522-6.
