A study published in 2013, a single-blind, placebo-controlled, split-face comparative study in 22 individuals over 60 days, evaluated the efficacy of green tea, as well as green tea plus lotus, compared with placebo for controlling casual sebum secretions in healthy adults. Compared with placebo, consistent and statistically significant decreases in sebum secretions were observed in both treatment groups. The combination of green tea and lotus extracts also achieved statistically sounder results than green tea alone. The investigators concluded that a synergistic interaction between green tea and lotus extract constituents appears to hold promise for the treatment of skin conditions in which elevated sebum levels are involved.23
Anogenital warts
In 2006, the Food and Drug Administration approved for the first time a botanical drug formulation for the topical treatment of genital and perianal warts: sinecatechins, derived from green tea catechins and other C. sinensis constituents in a topical 15% ointment (Veregen).21, 24-28
Two years later, Tatti et al. conducted a randomized, double-blind, vehicle-controlled trial to evaluate the efficacy of topical sinecatechins in 502 male and female patients (aged 18 years and older) for the treatment of anogenital warts. For 16 weeks or until complete clearance, subjects applied sinecatechins ointment 15% or 10% or vehicle (placebo) three times daily. Complete clearance was achieved in 57.2% of patients treated with 15% ointment, 56.3% using 10% ointment, and 33.7% who used only the vehicle. Respective recurrence rates, after 12 weeks, were 6.5%, 8.3%, and 8.8%. The investigators concluded that topical sinecatechins in 15% and 10% concentrations represent effective and well-tolerated options for anogenital wart treatment.29
Similarly favorable results regarding polyphenon E 15% were reported in reference to three placebo-controlled clinical studies in 1,400 patients with genital warts from Europe, North and South America, and South Africa,30,31 and by Tatti et al. again in 2010 after randomized, double-blind, vehicle-controlled safety and efficacy trials in nearly 1,000 patients treated with polyphenon E 15% and 10% formulations.21
Two years later, investigators evaluated sinecatechins (Polyphenon E) 10% ointment in two double-blind, multinational studies in adults with external genital and perianal warts. Polyphenon E 10% was found to be significantly more effective than vehicle in completely or partially clearing all warts.32
Earlier that year, a review of the use of sinecatechins ointment for the treatment of external anogenital warts noted that while clearance rates are similar among sinecatechins and other indicated topical medications such as imiquimod and podophyllotoxin, recurrence rates are lower for patients treated with sinecatechins. The authors concluded that the use of sinecatechins for condylomata acuminata was safe and effective and its various molecular activities suggest broader applications to other viral and tumor lesions.33
In 2015, Gupta and Daigle reported that sinecatechins 10% ointment for the treatment of external genital warts was found in phase III trials to display greater efficacy and lower rates of recurrence in comparison to patient-applied treatments now available.28 Later that year, in a systematic PubMed and Embase review of clinical trials involving the use of polyphenol-based therapies, Tuong et al. identified cogent evidence suggesting the effectiveness of green tea polyphenols for the treatment of anogenital warts.34
Antiaging activity
Green tea has been shown to work in combination with red light to exert a rejuvenating effect on the skin, as Sommer and Zhu reported in 2009 that green tea filled cotton pads applied once daily for 20 minutes prior to treatment with light-emitting diodes (central wavelength 670 nm, dermal dose 4 J/cm2) reduced wrinkles in 1 month comparably to 10 months of light treatment alone.35
In 2013, Hong et al. studied the antiwrinkle effects of topically applied green tea extract with high antioxidant activity after tannase treatment. Study participants were randomly divided to receive either green tea extract or tannase-converted green tea extract on their crow’s feet for an 8-week period. The investigators found that tannase treatment elevated the antioxidant activity of green tea and imparted antiwrinkle effects.36
At around the same time, Gianeti conducted clinical studies in 24 volunteers to assess the effects of a cosmetic formulation containing 6% C. sinensis glycolic leaf extracts. Skin moisture was enhanced after 30 days of topical application as was the viscoelastic-to-elastic ratio compared with vehicle and control (a forearm area left untreated). Skin roughness was significantly diminished after 30 days. The investigators concluded that the topical cosmetic formulation with green tea yielded salient moisturizing and cutaneous microrelief benefits.37
Also in 2013, oral intake of green tea catechins in 16 healthy human subjects (with 14 completing the study) appeared to result in the integration of catechin metabolites into human skin linked to the negation of UV-induced 12-hydroxyeicosatetraenoic acid (12-HETE). The investigators speculated that this incorporation of catechins may render protection against sunburn inflammation and even cumulative UV-induced harm.38