Last week, sandwich giant Subway announced that in the coming years, its U.S. restaurants will serve only animal proteins that have never been treated with antibiotics. This is a bold statement that has been months in the making, as consumer and public health groups have pressured Subway to reduce the use of antibiotics in its source animals. With its commitment, Subway joins other establishments that are either currently using animals raised without antibiotics or have pledged to do so in the future — restaurants including Chipotle, Panera, McDonald’s and Chick-fil-A.

Now that Subway has promised to implement this step, what does it mean? And critically, what makes a meat product “antibiotic-free”?

The term “antibiotic-free” meat is actually something of a misnomer. Despite the headlines stating such things as “Subway pledges to nix antibiotics in all its meat by 2025” and “Subway joins the fast-food, antibiotic-free meat club”, the concern here really isn’t antibiotic drugs in meat you eat. Antibiotic residues in meat products are already regulated, and farmers who use antibiotics in their herds or flocks of animals need to conform to strict dosing schedules, including withdrawals of antibiotics at certain time points before the animals go off to slaughter. As such, you shouldn’t expect to consume antibiotic drugs in any meat product, and new production guidelines won’t change that.

The real concern is what happens when the animals are routinely dosed with antibiotics — even if none of the drugs sticks around long enough for humans to get a taste.

Livestock and poultry can receive antibiotics for various reasons besides illness, including speeding up growth of the animals (“growth promotion”), and preventing disease (“disease prophylaxis”). Using antibiotics for any of these reasons can result in the breeding of “superbugs” — bacteria that have evolved to resist the antibiotics being used. These bacteria can be found on and in the animal, including in their feces. During slaughter, these superbugs can then enter the food chain via the animal’s meat and end up in the consumer’s kitchen -- or in their gut. If these resistant bacteria cause illness, it may be more difficult to find a working antibiotic for treatment.

No one denies that sometimes, sick animals do need antibiotics. Even on farms that do not use antibiotics in routine husbandry practices, antibiotics will be used if animals become ill. In fact, organic standards (which also disallow antibiotic use) note specifically that “If approved interventions fail, the animal must still be given all appropriate treatment(s). However, once an animal is treated with a prohibited substance (e.g., antibiotics), the animal and/or its products must not be sold as organic post-treatment.”

Russ Kremer, a Missouri farmer who has raised swine without antibiotics for 25 years, notes that in his management system, he is intently focused “on management practices that prevent‎ illness and death.” These include improvement of housing conditions, reduction of population density, and providing probiotics and herbs in the pigs’ diets. His results from this, he says, are “healthier animals with a dramatic reduction in mortality rate.” However, he agrees that “if animals need treatment, therapeutic treatment of antibiotics is administered and the animals are sold in a different system.” Farmers who are responding to Subway’s news suggesting that compliance means additional animals will die are either uninformed or intentionally misleading consumers.

Use of antibiotics in livestock and poultry is a big deal. It’s estimated that approximately 70 percent of all antibiotics used in the United States that are important to human health are used in livestock. Although the use of antibiotics for growth promotion is scheduled to be phased out starting next year, companies that are taking it a step farther and selecting meat products raised without any antibiotics are a welcome change to those in public health who have been arguing for a reduction in the use of antibiotics in agriculture for decades. David Wallinga, a physician and senior health officer with the Natural Resources Defense Council who has been working on antibiotic-resistance policy for 15 years , notes: “When the world’s largest restaurant chain commits to ending routine antibiotic use in their supply chains, it’s a big deal for public health. We look forward to working with Subway to make sure they succeed in meeting their goals, and hope the rest of the industry follows their lead.”

Tara C. Smith, an associate professor of epidemiology at Kent State University, studies infectious disease with a focus on antibiotic resistance and infections which move between animals and people. She writes about these topics at Aetiology as well as for Slate, Mental Floss and other venues. Follow her on Twitter or Facebook.

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