Double-Blinded, Placebo-Controlled Trial of Green Tea Extracts in the Clinical and Histologic Appearance of Photoaging Skin

Department of Dermatology, Emory University, USA.
Dermatologic Surgery (Impact Factor: 2.11). 07/2005; 31(7 Pt 2):855-60; discussion 860. DOI: 10.1111/j.1524-4725.2005.31731
Source: PubMed


Green tea extracts have gained popularity as ingredients in topical skin care preparations to treat aging skin. Green tea polyphenolic compounds have significant antioxidant and anti-inflammatory activities, and studies suggest that these extracts help mediate ultraviolet radiation damage.
To evaluate the effects of a combination regimen of topical and oral green tea supplementation on the clinical and histologic characteristics of photoaging.
Forty women with moderate photoaging were randomized to either a combination regimen of 10% green tea cream and 300 mg twice-daily green tea oral supplementation or a placebo regimen for 8 weeks.
No significant differences in clinical grading were found between the green tea-treated and placebo groups, other than higher subjective scores of irritation in the green tea-treated group. Histologic grading of skin biopsies did show significant improvement in the elastic tissue content of treated specimens (p<.05).
Participants treated with a combination regimen of topical and oral green tea showed histologic improvement in elastic tissue content. Green tea polyphenols have been postulated to protect human skin from the cutaneous signs of photoaging, but clinically significant changes could not be detected. Longer supplementation may be required for clinically observable improvements.

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    • "Green tea extract (GTE) has been extensively studied as herbal remedy due to antioxidation [1] [2], antihypertension [3], antimutagenicity [4], anticarcinogenesis [5] and enhancing glucose tolerance [6] effects to protect against cardiovascular diseases [7], ultraviolet attack [8], oral diseases [9] and obesity [10]. These effects are mainly attributed to the multiple target properties of GTE in signaling and regulatory pathways. "
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    ABSTRACT: Green tea extract (GTE) exerts antioxidative activities in ocular tissues of rats, but high levels of (-)-epigallocatechin gallate (EGCG) can induce oxidative stress. In this study, pharmacokinetics, diurnal variation of oxidative status, antioxidation and transcription factors changes in ocular tissues of rats were investigated. Rats were fed intragastrically with GTE and catechin mixtures containing different amounts of EGCG. Plasma and various ocular tissues were taken for pharmacokinetic analysis, oxidation marker testings and gene expression assays. Effects of EGCG on ocular oxidation status were assessed by 8-isoprostane level and reduced/oxidized glutathione ratio. Oxidation, inflammation and apoptosis regulations in retina were evaluated by real-time polymerase chain reaction. Epicatechin, epigallocatechin and EGCG were dominant in various ocular tissues except vitreous humor, where gallocatechin was predominant. Diurnal variation of oxidative status was found in some compartments. GTE caused oxidative stress increase in the plasma, aqueous humor, vitreous humor, cornea and retina but decrease in the lens and choroid-sclera. Catechins mixture containing half dose of EGCG lowered 8-isoprostane in the retina and lens. GTE treatment induced superoxide dismutase 1 and glutathione peroxidase-3 expressions but suppressed catalase in the retina. Our results reveal pro-oxidation of GTE with high EGCG content to the ocular tissues. Optimal EGCG level is needed for protection.
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    • "(2005) "
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    ABSTRACT: Tea is the most consumed drink in the world after water. The medicinal value of teahas been historically well known and since ancient times, green tea has been consideredas a healthy beverage. In recent years, green tea's potential health benefits haveextensively been investigated. In the early years, scientists focused their research on themain polyphenolic group present in green tea, catechins, and their anticancer effects.Nowadays the health benefits of green tea catechins (GTC) are increasingly beingexplored against uprising diseases such as diabetes, metabolic syndrome andcardiovascular diseases.Epidemiological studies have indicated metabolic health benefitsfrom regular consumption of green tea. Furthermore, cell and animal studies haveprovided data on the role of GTC in the regulation of glucose uptake from cells, insulinsensitivity or even regulation of beta cells function. Therefore, GTC health benefits led tothe conclusion that green tea can be considered as a beverage with functionalproperties.However, although all the evidence from research on green tea are verypromising, future studies are necessary to fully understand its contribution to humanhealth.The aim of this chapter is to summarize the latest research (cell, animal, humanand epidemiological studies) on the effects of GTC (epigallocatechin-gallate,epigallocatechin, epicatechin-gallate and epicatechin) against conditions accompanying diabetes pathology such as reduced glucose uptake, insulin resistance and beta cellsfunction.
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    • "Sunscreen formulated with 2–5% green tea extract has been reported to protect UV irradiation induced photoaging, photoimmunosuppression, cutaneous erythema, thickening of the epidermis, overexpression of CK5/6, CK16, MMP-2, MMP-9, etc. (Li et al. 2009). A double-blind, placebo-controlled trial have been executed with moderate photoaging treated with either a combination regimen of 10% green tea cream and 300 mg twice-daily green tea oral supplementation or a placebo regimen for 8 weeks to monitor the clinical and histologic appearance of photoaging skin (Chiu et al. 2005). It has been found that patients treated with a combination regimen of topical as well as oral showed histological improvement in tissue elastic content, but clinically significant changes have not been observed and it may require longer supplementation for clinically observable improvements. "
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