Employees work at a traditional Chinese medicine shop in Shanghai, China, September 16, 2015. China's much-hyped market for vitamins and supplements is facing a steep challenge from traditional remedies from ginseng to deer antler, even as the sector's rise fuels billion-dollar deals and share price surges. The vitamins market is set to expand five percent a year to $20 billion in 2019, half its pace of growth since 2009. It's being outstripped by a traditional medicine business that could be worth $40 billion by then - and is growing twice as fast. Picture taken September 16, 2015. To match CHINA-HEALTHCARE/VITAMINS REUTERS/Aly Song