Human hair, like soybean, wheat, and bran, is rich in protein and amino acids, key components in food production. In Hubei province in China, a factory processes over ten tons of human hair daily to extract edible amino acids, which are then used to produce soy sauce. Until recently, human hair was also a common source of L-cysteine, a food additive used worldwide. While unconventional, this practice highlights the complex and sometimes controversial methods used in the food industry to maximize resource efficiency.
