http://www.theguardian.com/lifeands...3/10-gross-ingredients-food-horsemeat-scandalAmino acids are your body's building blocks, and while they can be good for your health, not all amino acids are created equal. L-Cysteine – an amino acid used to prolong shelf-life in products such as commercial bread – can be found in duck and chicken feathers and cow horns, but most that's used in food comes from human hair. It has been reported that most of the hair used to make L-Cysteine comes from China, where it's gathered from barbershops and hair salons. You can avoid L-Cysteine by buying fresh bread from a local baker, as it is not an additive in flour. Steer clear of fast food places such as McDonald's, Dunkin' Donuts and Burger King too, who all use L-Cysteine as an additive.