Science Friday - What Are The Risks Of Drinking Raw Milk?

Episode Date: July 25, 2024

According to a 2022 study, just over 4% of Americans said they had consumed raw milk in the past year. That might not sound like a lot, but it adds up to around 15 million people. And those numbers seem to be increasing. According to data from the market research agency NielsenIQ from May, sales of raw milk increased by as much as 65% compared to that time last year.This increase coincides with a recent trend of influencers and other public figures promoting raw milk as a completely safe and healthier alternative to pasteurized milk.But despite claims about its safety, raw milk is more likely to contain pathogens than pasteurized milk, which is heated to kill harmful microbes. According to records released last week, some 165 people were sickened by salmonella linked to raw products from a single farm in California as of February, the largest raw milk-related salmonella outbreak in a decade. And the CDC recently reported that dairy cows in 13 states were infected with the H5N1 virus, also known as bird flu.Host Rachel Feltman is joined by Dr. Céline Gounder, editor-at-large for public health at KFF Health News and Dr. Nicole Helen Martin, assistant research professor in dairy foods microbiology at Cornell University, to talk about the dangers of health misinformation and how the risks of drinking raw milk can far outweigh its potential benefits.Transcripts for each segment will be available after the show airs on sciencefriday.com.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Lately, you may have seen lots of social media influencers promoting raw milk. This is why you should be drinking raw milk. I love raw milk. I drink raw milk every day. The reason that we love buying dairy from the Amish is that they don't pasteurize their dairy. Let's talk about my raw milk consumption. Those influencers may be having, well, an influence. It's Thursday, July 25th, and you're listening to Science Friday.

I'm SciFry producer Charlesburg Quist. According to a 2022 study, just over 4% of Americans said that they had consumed raw milk in the past year. Now, that might not sound like a lot, but it adds up to around 15 million people. And the numbers seem to be increasing. According to May data from the Market Research Agency Nielsen IQ, sales of raw milk increased by as much as 65% compared to the same time last year. Despite claims about its safety, raw milk is more likely to contain pathogens and pasteurized milk, which is heated to kill harmful microbes. Here to talk with experts about the dangers of health misinformation

and how the risks of drinking raw milk can outweigh its potential benefits is guest host Rachel Feldman. Just last week, more than 150 people in California were infected with salmonella from raw milk, marking the largest outbreak in the past decade linked to unpasteurized dairy. But raw milk can also expose you to viruses. The CDC recently reported that dairy cows in 13 states were infected, with the H5N1 virus, also known as bird flu. And several studies have shown that when sick cows get milked,

their bird flu can go along for the ride. It's an example of how, when it comes to health information and misinformation, it's important to find sources you can trust. Here to tell us more are my guests. Dr. Celine Gounder, editor at large for public health at KFF Health News and Infectious Disease Specialist, and Dr. Nicole Martin, assistant research professor of dairy foods microbiology at Cornell University. Thank you both so much for joining me.

Great to be here. Thanks for having me. Dr. Gander, let's start with the big picture. Where did this trend of drinking raw milk come from? And how has it gotten widespread enough to show up on so many people's social media feeds? Well, I think we've seen this surge in popularity with raw milk connected to the H5N1 bird flu outbreak among cows. And I think whenever you see something new, something where there might potentially be a political angle on it, you're going to see people come up with mis and disinformation around it. I think there is a lot of appropriate concern about overly processed food and wanting healthier alternatives, right?

But having food that is appropriately cooked, heated, refrigerated, frozen, that's really not about processing. It's about keeping food safe and healthy. Yeah, I definitely want to get more into those valid concerns in a minute. But first, Dr. Martin, what are the differences between pasteurized and unpasteurized milk? A basic question, I know. But fill us in. Absolutely. So, pasteurization, as you might know, has been around for quite some time. This is a gentle heat treatment that is designed specifically to kill the most heat-resistant pathogens that are found in. raw milk. So raw milk is as it comes from the cow or the farm. It has not been processed in any way. And that pasteurization is conducted at a couple of different temperatures. But here in the United States,

we primarily use what's called high temperature short time pasteurization, which is a very, very brief heat treatment. It's 162 degrees Fahrenheit for 15 seconds. So very quick. But it is effective at eliminating those pathogens or bacteria that can make people ill. And I know that it's a common refrain from raw milk fans that unpasteurized dairy retains certain health benefits that don't make it through pasteurization. Is there any truth to that at all? There's really not. So I hear this a lot from various folks.

And there's a lot of belief systems to that idea that raw milk is in some way healthier. than nutritionally healthier than pasteurized milk. But the reality is this is a very mild heat treatment. It has very minimal impact on the constituents of the milk itself. There's lactose in raw milk and there's lactose in pasteurized milk. There's protein in both. We see some very minor decreases in certain heat, labile or heat sensitive enzymes, but nothing to the degree that would confer a health benefit by drinking the raw milk. And when we're talking about, you know, the risks of drinking unpasteurized milk, what types of pathogens are we talking about and what kinds of problems can they cause?

Well, as you mentioned earlier in the segment, Salminoa is one. We also know that Listeria, E. coli, Kamplobacter, that's a very common pathogen that we see, causing outbreaks in the United States from raw milk consumption. So there's a whole host of pathogens that we can find naturally in raw milk. And those cause varying degrees of illness in humans, right? So gamplabacter is, you know, it's unpleasant. Nobody wants to get it. People would, you know, probably think, oh, I've, you know, I've got some sort of flu or,

you know, gastrointestinal thing, right? But then on the other end of that spectrum, we have a pathogen like Listeria, which has a mortality rate of 15 to 20 percent. So folks who get ill with that pathogen, a lot of them die. And so that's certainly much more serious, right? And we can't tell just by, you know, looking at an animal or looking at a farm or looking at the milk itself, if these harmful bacteria are present or not. Am I remembering correctly that Listeria is particularly dangerous for pregnant people, too? That's right. And that's why there are guidelines about eating things like soft cheeses during pregnancy because Listeriosis is particularly harmful to pregnant individuals, children, immunocompromised and elderly individuals. So those populations in particular can become very, very ill and often die.

with pregnant women, in fact, this disease often causes miscarriage or spontaneous abortion. Getting back to how these pathogens get into unpasteurized milk, you know, you mentioned that we can't tell from looking at milk, from looking at the farm. And, you know, Dr. Gounder had alluded to, you know, very valid concerns people may have with a more industrialized food processing. So for people who are really focused on the fact that, you know, they're getting this from a trusted farmer. It's a local farm and they really see benefits to that over, you know, buying a gallon of milk at a supermarket. You know, what would you tell them about where the actual risks of contamination are? As we all know, dairy cows live on farms, right? These are agricultural locations.

There is a variety of sources. where bacteria can live and contaminate the animal or the milk itself. So we have soil and water and manure, obviously. Cows produce a lot of manure. They eat a lot of food. They produce a lot of manure. Cows can also become infected with certain pathogens, right? So they can have sort of disease themselves from pathogens.

But they can also have what we call subclinical disease. And that's when an animal is infected and can shed that that bacteria into the milk but shows no signs of being ill. And that is where one of the big concerns come from and people can say, oh, I choose raw milk, but I know this farm. I know these animals. They look healthy. They're very clean. The farm is very clean. All of that can be absolutely true.

And I've been on those farms. But they can still contain the harmful bacteria. that can make people ill. You just can't use your senses to determine that. Yeah. And Dr. Gounder, back to you. I want to circle back to H5N1. You know, I find it so interesting that this is getting people excited about raw milk since, as we know, bird flu has spread to cows and there have been a couple of, and there have been several cases of transmission to humans, you know, from farm workers. Does bird flu and raw milk pose a direct risk to humans that we know of? People who drink raw milk risk not only getting H5N1 bird flu infection, but also E. coli, salmonella,

campelobacter, and listeria bacterial infections. These bacteria are present in the feces of cattle. And when you think about the anatomy of a cow, the undersides of cattle are going to be highly contaminated with these bacteria. The udders of the cow are on the underside of the cow. So there is really no way to sterile milk a cow and be sure that there is no bacteria entering the milk at that point. Ecoli, campelobacter, salmonella infections can cause fever, diarrhea, and abdominal pain, but they can also cause more severe disease, including bloody diarrhea, kidney, failure and other complications. Listeria, as Dr. Miller noted, can cause meningitis, and infection during pregnancy can be highly morbid and even fatal for the fetus or the newborn. Now, does bird flu pose a

direct threat to people at this stage? If you are infected with bird flu, yes, there is a concern historically about half of people who have been infected with H5N1 bird flu, and this is around the world, half of those people have died. So far in the United States, the cases have been pretty mild. We don't entirely know why. The good news is that pasteurization kills the virus in the milk. The FDA and the USDA have done numerous tests now looking at different durations and temperatures of pasteurization, and that is effective in killing the virus in the milk.

But we've also done testing on pasteurized milk in grocery stores and other retail settings. And we are seeing fragments of dead virus. So, of course, it's been killed by the pasteurization process. But we are seeing fragments of dead virus in that milk, which means it was there. The pasteurization worked. But if you're drinking raw milk, you are certainly putting yourself at risk for infection. Yeah. No, that makes a lot of sense.

We talked a little bit about some of the supposed benefits that there's no evidence for in raw milk. But, you know, folks also say, oh, it's better for lactose intolerance or even just that it tastes better or, you know, it grants some kind of strengthened immunity for children just to clarify, you know, is there any evidence there or is it really clear that the risks outweigh the benefits? Certainly from a from a scientific and data person. perspective, the risks absolutely outweigh the benefits, and we have plenty of studies that demonstrate that. And we know that in states where the sale of raw milk is legal, that there is hugely higher risk of contracting illness related to raw milk consumption, right? So the data is

there. We have plenty of evidence that these risks are real and no evidence that the benefits are real, right? But I do want to touch just briefly on something that you said. You said, some people say that the flavor is better. That really can be the case in, you know, based on personal perception. So, but it's really driven by the fact that when you choose to consume milk from one farm, you're getting all of the flavor profiles from that one farm, right? Typically, raw milk has much higher fat level than pasteurized milk when we pasteurized milk. Often we standardize, which means we sort of take the fat out and put it back in in a standardized way. We don't want one one gallon of whole milk to have 3.2% fat and the next to have 4% fat, right?

We want to have sort of a level playing field for everybody. Typically, when we pasteurized milk, when milk goes from various farms into the same processing facility, and then they all get what we call co-mingled, right? They're commingled together. and that kind of levels out some of those differences that you might see on a flavor perspective because all of that milk is going in the same tank. And again, I'll go back to this idea that you can get a pasteurized product that is a safe product from a single farm on farms that do that or for small processors.

You can also get milk that's not been homogenized, which is when we sort of break up the fat so that it doesn't rise to the top. Some people like that cream rising to the top, right? and you get a certain flavor profile from that. So again, I just want to come back to the idea that if that's the value proposition for a consumer, that they like that unique flavor from a certain farm or they like the higher fat level, you can get all of those things in a pasteurized product and not have the risk of the foodborne disease. Yeah.

So, you know, perhaps for people who are already into raw milk or are curious about it, like perhaps try a local trusted farm that you like the look of that also pasteurizes their dairy. And maybe your results will be even better. And Dr. Gounder, there's such an understandable instinct that people are reacting to. They want to make healthy choices for themselves and their family. So, you know, I do empathize with folks who, you know, are drawn to this kind of content on social media. What are some ways that people can make sure that the information they're taking in is trustworthy? I think start by looking at what the source is.

So legitimate media organizations, journalistic organizations, have ethical standards of journalism, and they should have them posted on their site. So, for example, the New York Times has an ethical journalism handbook. So I would search whether there is such an ethical guideline for that particular publication that tells you a lot about whether that's a trustworthy source. Secondly, who is actually providing the information or quoted as providing the information? Is it somebody who is an expert, a specialist in the relevant field? And I'll give you an example where just having a credential is not.

necessarily being an expert in the field. So we saw a lot of doctors, MDs during COVID, who professed to be experts in COVID that they were actually neurologists or radiologists, et cetera. So look and see whether the person has the appropriate, relevant expertise. So I think that's two places to start to figure out if the advice information you're being given is something you can trust. Yeah. No, that's great advice. I think that's just about all the time we have for the hour. I'd like to thank my guest once again, Dr. Celine Gounder, editor at large for public health at KFF Health News and infectious disease specialist and epidemiologist, and Dr. Nicole Martin, assistant research professor in dairy foods microbiology and food science at Cornell University.

Thank you both so much for coming on the show this week. There was so much helpful information in there. Thanks so much. My pleasure. That's it for today's show. Lots of folks help make it happen, including Jordan Smudjick Diana Plasker Santiago Flores Rasha Auredi Phyllisoma On tomorrow's episode

we'll check in on some of the week's top stories in science I'm SciFry producer Charles Berkwist Thanks for listening