In an article called "Hair Soy Sauce: A Revolting Alternative to the Conventional" for the Internet Journal of Toxicology, Alexander Tse-Yan Lee exposed that a cheap soy sauce brand in China marketed as "blended using the latest bioengineering technoloogy" had a secret ingredient: amino acid made from human hair!
The journalists then found the amino acid syrup manufacturer (a bioengineering company) in Hubei province. When asking how the amino acid syrup (or powder) was generated, the manufacturer replied that the powder was generated from human hair ( 1 , 2 , 3 ). Because the human hair was gathered from salon, barbershop and hospitals around the country, it was unhygienic and mixed with condom, used hospital cottons, used menstrual cycle pad, used syringe, etc (figure 1). After filtered by the workers, the hair would then cut small for being processed into amino acid syrup
Link - via Fortean Times