According to a study published in the British Journal of Nutrition in September 2013, compounds in green tea may help to protect skin from damaging UVA and UVB rays. In contrast to topical sunscreens that deflect the sun's rays, however, green tea compounds work from the inside out.
Green tea (Camellia sinensis) is abundant in catechin polyphenols, phytochemicals with potent antioxidant and anti-inflammatory properties. While applying green tea formulations topically is certainly beneficial to the skin, this team of researchers found that consuming 540 mg of green tea extract each day for three months significantly reduced the incidence of sunburn in more than a dozen fair-skinned men and women. Specifically, the study subjects experienced less UV radiation-induced inflammation and evidenced intact catechin metabolites in skin tissue and fluid.
Does this mean it's safe to skip the sunscreen with green tea supplementation? No, it does not. But, in addition to potentially lowering serum cholesterol, blood pressure and the risk of cancer, it does suggest one more benefit to incorporating green tea into your diet on a regular basis. It should also be noted that tea drinking is, hopefully, an enjoyable, often meditative experience. That alone makes it a valuable part of a holistic lifestyle. But, back to those happy little catechins...
To put things into perspective, green tea standardized extract contains about 30% catechins. Estimates vary as to how many milligrams of catechins is in a cup of green tea, with some reports claiming more than 140 mg per cup. For illustration purposes, let's go with the 2007 study conducted by the US Department of Agriculture (USDA) which states that one gram of green tea steeped in 100 milliliters of water yields 127 milligrams of catechins. Since a cup is 240 ml, 100 ml is equivalent to 0.416 cups, or nearly half a cup. This means that as little as about 3 cups of green tea daily is enough to make a positive impact. So drink up!
Reference "Oral green tea catechin metabolites are incorporated into human skin and protect against UV radiation-induced cutaneous inflammation in association with reduced production of pro-inflammatory eicosanoid 12-hydroxyeicosatetraenoic acid."; Rhodes LE, et al; British Journal of Nutrition 2013 Sep 14;110(5):891-900. http://www.ncbi.nlm.nih.gov/pubmed/23351338