Composition for skin-whitening or preventing or improving skin wrinkles comprising green tea extract which has modified amounts of ingredients

A method for improving skin wrinkles, comprising:

• administering, to an adult human subject in need thereof, a steam-processed green tea extract containing 4 to 15 wt. % of (−)-gallocatechin gallate (GCG) and 5.27 to 15 wt. % of (−)-epigallocatechin gallate (EGCG), on the basis of the total weight of the extract,
• wherein the weight ratio of GCG:EGCG in the extract is 1:0.5 to 1:2,
• wherein administering the green tea extract exhibits inhibition activity of MMP-1 (matrix metalloproteinase-1) of the human subject, and
• wherein the total amount of EGCG, epigallocatechin (EGC), (−)epicatechin (EC), epicatechin 3-O-gallate (ECG), GCG, gallocatechin (GC), catechin (C) and catechin gallate (CG) in the extract are from 21 to 30 wt. %, on the basis of the total weight of the extract.