Human hair contains a significant amount of L-cysteine, an amino acid that is often utilized in food products like meat flavorings and dough. This fact has sparked discussions among scholars of Jewish dietary laws, known as kashrut, regarding the permissibility of hair in food. Rabbi Zushe Blech asserts that human hair is, in fact, considered Kosher, as it does not possess any undesirable qualities that would render it unsuitable for consumption.

Blech explains that when hair is dissolved in hydrochloric acid, it transforms into L-cysteine, making it unrecognizable and removing any potential contamination. Thus, while the idea of using human hair in food may seem unappealing, it is deemed acceptable from a kashrut perspective, highlighting the complexities of dietary laws and the chemistry behind food ingredients.