. The major commercial sources of L-cysteine today are Chinese and Indian avian feathers and human hair. Hog’s hair as a source is likely when the hair/feather supply is low. Because the industrial plants needed to extract L-cysteine exist in China, most of the extraction is done there (i.e., it’s too costly for companies to ship feathers/hair and extract it here when the feathers, hair and industrial plants are already there).
Dark hair is richer in L-cysteine than light hair. Although there is no technical difference between L-cysteine derived from feathers versus that derived from human hair, industry sources have told us that human hair-derived L-cysteine is considered better and preferred in Europe.
- See more at: http://www.vrg.org/blog/2013/04/22/information-about-l-cysteine/#sthash.AvmhqiMw.dpuf