Subway is addressing one of the biggest criticisms of the brand

Subway will completely eliminate antibiotics from its meat over the next 10 years, the company announced Tuesday.

The world's largest sandwich chain will start introducing chicken and turkey raised without antibiotics next year.

The chicken rollout will be completed by the end of 2016 and the turkey rollout will take two to three years, the company said.

The transition to pork and beef raised without antibiotics will take much longer.

Subway estimates it will take six years to start the rollout of antibiotic-free pork and beef, and expects to finish the transition by 2025.

The announcement addresses one of Subway's biggest problems: the perception that its food is unhealthy.

Subway grew into the world's largest sandwich chain by advertising its sandwiches as a healthy choice to stay fit and even lose weight.

But consumers' definition of "healthy" has changed over the years, while Subway's offerings have largely stayed the same.

More customers now demand food free of antibiotics, preservatives, and other additives.

Subway also decided earlier this year to start removing artificial colors, flavors, and preservatives from its food.

"Today's consumer is ever more mindful of what they are eating, and we've been making changes to address what they are looking for," said Dennis Clabby, executive vice president of Subway's Independent Purchasing Cooperative. "A change like this will take some time, particularly since the supply of beef raised without antibiotics in the US is extremely limited and cattle take significantly longer to raise. But, we are working diligently with our suppliers to make it happen."

McDonald's also recently announced changes to the antibiotics used in its supply chain.

The company said it would transition to antibiotic-free chicken by 2017, as well as switch to cage-free eggs over the next 10 years.