Green tea extract is quickly becoming one of the most common ingredients in skin care formulations, like in Replenix Topix Cream or Esteé Lauder Daywear (shown above). But how effective is green tea in topical moisturizers?
Where does green tea come from?
Green tea comes from the steaming and drying of the tea plant Camellia sinesis.
Polyphenol EGCG as a Potent Antioxidant in Skin Care
Green tea contains the polyphenol epigallocatechin-3-gallate (EGCG), which has been shown to have remarkable preventive effects against photocarcinogenesis and phototoxicity in mouse models. While EGCG comprises only 50% of “green tea extract” found in skin care and cosmeceuticals (Mukhtar), there is still enough EGCG to demonstrate anti-inflammatory and anti-carcinogenic properties in most skin care and cosmeceuticals.
In a 2001 study in the journal Carcinogenesis, topical application of EGCG to human skin resulted in decreased oxidative stress and an increase in antioxidant enzymes after UV irradiation. Specifically, catalase and glutathione activity were increased due to the application of EGCG. A further 2003 study in Molecular Epidemiology and Cancer Prevention found that the polyphenols in green tea prevent UVB-induced oxidation of lipids and proteins and prevents against the depletion in antioxidant enzymes experienced after UVB exposure in mouse skin.
Fights against skin cancer
In a 1994 study in the mouse, Wang et. al. discovered that administration of 1.25% green tea extract (12.5 g green tea in 100 mL water) as the sole source of drinking water reduced the number and incidence of skin tumors that were induced with the agent 12-O-tetradecanoylphorbol-13-acetate.
In the journal Preventive Medicine, it was reported in a 10-year study of 419 patients in Japan that the first incidence of patients who had consumed more than 10 cups of green tea per day was 7.3 years later for females and 3.2 years later for males when compared to their gender-specific counterparts adjusted for lifestyle differences who had consumed under 3 cups per day. Unfortunately, considering that one 8 oz. cup of green tea contains about 20-40 mg of caffeine, ten-cup consumption may not be entirely good for your skin, as prolonged exposure to caffeine has been suggested by Whitmore and Levine to thin the skin. In addition, over 250 mg of caffeine (the amount in about twelve 8-oz. cups) is associated with restlessness, nervousness, insomnia, flushing of the face, increased urination, muscle twitching, irritability, and irregular heart beat and psychomotor agitation. Unfortunately, drinking decaffeinated green tea may also not have a preventive effect against skin cancer: “In our studies, if we remove the caffeine from tea and feed the decaffeinated tea to mice at a moderate dose, it loses most of its effectiveness at inhibiting … skin cancer,” says Allan Conney, Ph.D., director of the Laboratory for Cancer Research at Rutgers University College of Pharmacy in New Jersey.
Despite the probability of thinning the skin and experiencing caffeine overdose symptoms, according to a 1999 study by Fujiki et. al., there were no severe adverse effects among patients who volunteered to consume 15 green tea tablets per day for 6 months (2.25 mg green tea extracts, 337.5 mg EGCG, 135 mg caffeine).
Prevents AGE Formation
It has been reported that the advanced glycation endproduct glucosepane is responsible for the hardening of collagen as one ages. Unfortunately, green tea was found by a study in the Archives of Biochemistry and Biophysics to be more effectual against advanced glycation endproduct formation in the aorta than in the skin of the mouse. Despite this finding, what is good for your circulation is good for your skin, so consuming green tea daily to prevent advanced glycation endproducts in your aorta is a good idea, even if it doesn’t help your skin’s collagen!
Is green tea safe in skin care formulations?
According to Dr. Leslie Baumann’s Cosmetic Dermatology, no contact allergies have been reported from green tea.
Green tea is an excellent ingredient for the skin that exhibits many beneficial effects for the skin when consumed orally, including antioxidant, anti-inflammatory, anti-carcinogenic and photoprotective properties.
Update on Green Tea and Rosacea (January 18, 2008)
According to Dr. Gary Goldfaden, M.D., “In a recent dermatological comparison study, the use of a lotion containing a tea extract produced a 70% improvement in rosacea compared to use of a lotion containing the base ingredients alone. This tea extract is rich in antioxidant polyphenols and contains a variety of potent flavonoids.” Verifying this is a 2003 study in the Journal of Nutritional Biochemistry, which reports that green tea reduces UVB-induced inflammation as measured by double-fold skin swelling. As such, products with a high concentration of green tea polyphenols, such as TOPIX Replenix Serum ($46.25, 4Derm.com), with reported green tea content that is 90% active polyphenols.