"According to the U.S. National Library of Medicine, a 2007 study by Korean scientists at the Seoul National University College of Medicine found that epigallocatechin-3-gallat, or EGCG, present in green tea promoted growth of hair follicles and stimulated the human dermal papilla cells to boost hair production.
According to the University of Maryland Medical Center, green tea can increase your metabolism. A faster metabolism may increase your hair growth rate." Link
"In a study of mice stricken with hair loss, research showed that hair loss was halted in all mice which received green tea in their drinking water and even triggered new hair growth in some of the mice. As for the mice who were not invited to the tea party, their hair loss continued." Link