The world's biggest sandwich chain says it's in the process of removing the chemical known as azodiacarbonamide from its sandwich breads — a chemical that Vani Hari, who runs the site FoodBabe.com, says is commonly used to increase elasticity in everything from yoga mats to shoe rubber to synthetic leather. It's used for the same reason in bread, she says, as a dough conditioner.

"We are already in the process of removing azodiacarbonamide as part of our bread improvement efforts despite the fact that it is USDA- and FDA-approved ingredient," the company says in a statement. "The complete conversion to have this product out of the bread will be done soon."

Fresh baked bread — and the perception of better-for you offerings — is a major deal to Subway. It's one of the chain's central selling points. Just last week, Michelle Obama sat and ate lunch before hosting a press conference at a Subway in Washington D.C. to commend the chain for joining her healthy eating initiative — pledging nutritious foods on its kids menu.

Food safety and health concerns have become a priority with American consumers who are pressuring the nation's biggest brands to respond. Early last month, General Mills bent to consumer pressure and received positive press after it announced that was removing GMOs from regular Cheerios.

Subway's announcement follows a petition that Hari, the activist, recently launched that asked Subway to stop using azodiacarbonamide in its bread. The ingredient is banned in the UK, Europe and Australia, notes Hari, who says that she is thrilled with Subway's actions.

"I commend Subway for finally responding to me and now over 58,000 concerned citizens. Their swift action is a testament to what power petitions and individuals can have," says Hari, in an email. " I'd like to note that current Subway sandwiches still have this ingredient, and I urge everyone not to eat their sandwich bread until they have finally removed the chemical."