According to Mary Roach in her book "Gulp: Adventures on the Alimentary Canal," human hair contains about 14 percent L-cysteine, which is an amino acid often used in food production, particularly for enhancing meat flavors and improving the elasticity of dough. This surprising fact raises interesting discussions among experts in Jewish dietary laws, also known as kashrut, regarding the status of human hair in food consumption.

Despite being derived from the human body, hair is considered Kosher, which further complicates the conversation around dietary regulations. While human hair may not be something one would want to eat, its use in food production highlights the intricate relationships between food science, dietary laws, and cultural practices.