Nutritionist Carrie Dennett shares the facts about antibiotic use in livestock, what "antibiotic-free" really means (and doesn't), and who's really responsible for the rise of antibiotic-resistant bacteria (hint: sometimes it's us).

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Three years ago, I wrote about antibiotic use in raising livestock, which was a problem — and still is, although much progress has been made. But when someone recently said to me, “I switched to almond milk because I heard that dairy milk contains antibiotics,” I realized there’s still some myth-busting to do.

It would indeed be bad if we were getting antibiotics in our milk — but we’re not. Tens of thousands of retail samples of pasteurized milk, cream, yogurt and sour cream are tested annually. Since 2010, none have tested positive for antibiotic residues (traces of leftover antibiotics), because there are multiple layers of safeguards to make sure that doesn’t happen. On dairy farms, if a sick cow must receive antibiotics, that cow’s milk will be dumped until the antibiotics have cleared her system. In organic dairy production, the rules are even stricter — if a cow needs antibiotics, her milk can’t be sold as organic, even once she’s in the clear. When a milk truck comes to pick up a dairy’s milk, the driver takes a sample of the milk. Once the driver arrives at the milk plant, another sample is taken and tested. Any batch of milk — no matter how large — that tests positive for traces of antibiotics at any point is thrown out.

What about meat and poultry? According to the Centers for Disease Control and Prevention (CDC), strict rules mandate that no antibiotics be in an animal’s system when it is slaughtered. This further ensures there are no antibiotic residues in the meat or poultry you eat in a restaurant or buy at the grocery store.

What “antibiotic-free” means (and doesn’t)

With that in mind, what does it mean when you see the words “antibiotic-free” on a food label? Very little, because there’s no official definition of what “antibiotic-free” means — it’s not a term approved by the United States Department of Agriculture (USDA). Food producers and manufacturers might be implying that the animals the food comes from were never given antibiotics, or they might be simply stating that there are no traces of antibiotics in the final product, per government rules.

No matter what “antibiotic-free” is intended to mean, what it doesn’t mean is that livestock animals are free of antibiotic-resistant bacteria. The reality is that all animals carry bacteria in their gut, and some of these bacteria can be resistant to antibiotics. That’s why it’s important to have good food-safety habits — wash hands before and during food preparation, keep raw meats separate from cooked foods or foods that will be eaten raw, and keep foods at safe temperatures when storing and cooking. No one wants to get a food-borne illness from any bacteria, but especially not from “superbug” bacteria that no longer respond to treatment with common antibiotics.

Dealing with antibiotic resistance

Antibiotic resistance is a serious problem government agencies have been trying to solve for decades. Antibiotics have saved millions of lives since the discovery of penicillin in 1928. But unfortunately, antibiotic-resistant bacteria followed close behind. Each year, about 2 million Americans get sick and 23,000 die because of bacterial infections that aren’t cured by antibiotics, according to the CDC. Using antibiotics when they aren’t medically necessary encourages the development and spread of antibiotic-resistant bacteria.

Antibiotic-resistant bacteria from livestock can spread to humans via many channels: soil, air, water and food. Studies have found high levels of contamination with antibiotic-resistant bacteria in meat sold in retail stores. In 2012, an outbreak of salmonella that was resistant to multiple antibiotics was traced back to ground beef sold in a supermarket. Additionally, food crops could be fertilized with manure containing antibiotic-resistant bacteria. This means the problem affects everyone — not just those who eat meat.

New FDA guidelines

To help stem the tide of antibiotic-resistant bacteria, new Food and Drug Administration (FDA) guidelines went into effect in early 2017. They aim to reduce the use of antibiotics that are important to human health in food-producing animals. The guidelines recommend only using these antibiotics to treat, control or prevent disease. This means giving healthy animals antibiotics to promote growth or increase feed efficiency is not appropriate. (The practice is primarily used in meat, not dairy, production.) That type of “sub-therapeutic” antibiotic use bathes the animal’s gut bacteria with low, continuous doses of antibiotics, killing off a lot of the normal bacteria, allowing antibiotic-resistant bacteria to multiply and thrive.

Unfortunately, unlike the rules forbidding traces of antibiotics in your food, the new FDA guidelines aren’t legally binding. That’s where food producers and retailers come in. This month, Costco announced that it will make the guidelines mandatory for its suppliers. Other food producers and retailers who have taken steps in this direction include Chipotle, Whole Foods, Panera Bread, Shake Shack and Applegate. Many criticize the food industry, but the reality is that some of the improvements we’ve seen in recent years — especially in animal agriculture — have come in part because industry players with large purchasing power demanded it.

The human problem

Appropriate use of antibiotics in food animals is one crucial element of the fight against antibiotic resistance, but using antibiotics appropriately in ourselves is another. It’s especially relevant during cold and flu season. Antibiotics don’t fight viruses — the cause of colds and flu — but some respiratory illnesses may be caused by bacteria. So don’t demand antibiotics when your doctor says they’re not warranted — the CDC estimates that about 30 percent of human antibiotic prescriptions are unnecessary — but don’t be a hero and refuse antibiotics if your doctor says you need them. Remember, when used appropriately, antibiotics can save lives. When you need them, use them exactly as directed, and if you are concerned about their effect on your beneficial gut bacteria, ask your doctor about taking probiotics.