Burger King will begin antibiotic-free chicken for 2017

Fast-food chains Burger King and Tim Hortons announced big changes for 2017. Both chains will begin serving only chicken raised without the use of antibiotics -- a move the owners of both brands, Restaurant Brands International, say is "critically important" to human medicine.

Restaurant Brands expects the changes to be fully implemented in U.S. stores in 2017 and in Canada in 2018.