Raw Milk Reality: Is Raw Milk Dangerous? | Chris Kresser

Raw Milk Reality: Is Raw Milk Dangerous?

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Full Bottle of fresh milk and two glass is wooden table on a blue background

Back in February, the Center for Disease Control (CDC) published a study targeting raw milk as dangerous and unsafe for human consumption. The media jumped on it in typical fashion. You may have seen headlines like this:

“Raw Milk Causes Most Illnesses From Dairy, Study Finds.”
– USA Today

“CDC: Raw Milk Much More Likely to Cause Illness.”
– Food Safety News

“Raw Milk is a Raw Deal, CDC Says.”
– LiveScience

While two of these headlines are technically accurate – raw milk is responsible for more illnesses than pasteurized milk when the number of people who consume each is taken into account – the concern they convey about the risk of drinking unpasteurized milk is dramatically overstated.

I’m going to break this series into three parts. In this first article, we’re going to examine what the research really says about raw milk safety, and compare the risks associated with drinking unpasteurized milk with other foods and activities. In the second article, we’ll explore the benefits of drinking raw milk from several different perspectives: nutritional, health-related, social, environmental and ethical. Finally, in the third article I’ll make recommendations and provide guidance on finding a safe and responsible raw dairy producer in your area.

This series is called “Raw Milk Reality” because, as is the case with other hot button issues like vaccination and homebirth, propaganda and hype have overshadowed facts and common sense.  If you only saw the headlines from the CDC and FDA reports, you’d be left with the impression that raw milk is a dangerous food and anyone that consumes it or gives it to their children is reckless and irresponsible.

The purpose of this series is to present the other side of the argument, and give you the bare facts without bias or hyperbole so you can make an informed decision about whether unpasteurized milk is a good choice for you and your family.

I’m not here to convince anyone that they should drink raw milk.  That’s a decision each individual has to make on their own by weighing the potential risks against the potential benefits.  But to do that, you need an accurate understanding of the risks (which we’ll cover in this article) and the benefits (which we’ll cover in the next.)

Just how “dangerous” is raw milk? A little perspective…

Before we do that, however, let’s put the current discussion of unpasteurized milk safety into a wider context. Foodborne illness is a concern for many types of food. According to the most recent review of foodborne disease outbreaks in the U.S. in 2008 by the Center for Science in the Public Interest (CSPI), seafood, produce and poultry were associated with the most outbreaks. Produce is responsible for the greatest number of illnesses each year (2,062), with nearly twice as many illnesses as poultry (1,112). Dairy products are at the bottom of the list. They cause the fewest outbreaks and illnesses of all the major food categories – beef, eggs, poultry, produce and seafood.

According to the CDC, during the period from 1990 − 2006, there were 24,000 foodborne illnesses reported each year on average. Of those, 315 per year are from dairy products. This means dairy products account for about 1.3% of foodborne illnesses each year. That’s not exactly an alarming number, considering that more than 75% of the population consumes dairy products regularly.

It’s also important to note that the outbreaks and illnesses associated with dairy products are generally mild compared to other foods.
According to the CSPI report above, approximately 5,000 people are killed every year by foodborne illness. From 2009 − 2011, three high profile outbreaks involving peanuts, eggs and cantaloupe alone accounted for 2,729 illnesses and 39 deaths. (1) Yet there have only been a handful of deaths from pasteurized dairy products in the last decade, and there hasn’t been a single death attributed to raw fluid milk since the mid-1980s, in spite of the fact that almost 10 million people are now consuming it regularly.

The takeaway is that thousands of people are killed each year by foodborne illness, but they’re dying from eating fruits, nuts, eggs, meat, poultry, fish and shellfish – not from drinking unpasteurized milk.

Why the CDC report can’t be taken at face value

The CDC report claimed that unpasteurized milk is 150 times more likely to cause foodborne illness than pasteurized milk, and such outbreaks had a hospitalization rate 13 times higher than those involving pasteurized dairy products.

According to senior author of the CDC study, Barbara Mahon:

When you consider that no more than 1% of the milk consumed in the United States is raw, it’s pretty startling to see that more of the outbreaks were caused by raw milk than pasteurized.

But can these claims be taken at face value? No.

There are several problems with the CDC report:

  • First and foremost, the CDC doesn’t include the dataset they used, so we can’t analyze how they reached their conclusions. Fortunately, the CDC data for foodborne illness, as well as data from other institutions and peer-reviewed studies, are readily available online.
  • There are about 24,000 foodborne illnesses reported each year. Yet by the CDC’s own admission, this represents only a tiny fraction of the true number of foodborne illnesses that occur. In 1999, CDC scientists used an estimate of the overall prevalence of diarrhea and vomiting to calculate the “true” incidence of foodborne illness as 76 million cases per year! Put another way, 99.97% of foodborne illnesses go unreported.
  • A food vehicle was identified in only 43% of the reported outbreaks and only half of these were linked to a single food ingredient. What this means is that the true prevalence of foodborne illness that can be attributed to a particular food is much higher than what is reported. It also means that the data linking specific outbreaks with specific foods is such a tiny sample of the total that even small errors or biases in the reporting of outbreaks would seriously skew the results.
  • To calculate the number of people that drink unpasteurized milk, the CDC used an older, lower estimate (1%) of the number of people that drink raw milk. This is curious because a FoodNet survey done by the CDC itself in 2007 found that 3% of the U.S. population – about 9.4 million people  – regularly consumes raw milk. That number is likely even higher today with the growing popularity of raw milk. (In 2010 alone, raw milk sales increased by 25% in California.) Why did they do this? If you’re a cynic, you might conclude that they used the lower estimate to exaggerate the risk of drinking raw milk.
  • They combined data from outbreaks and illnesses associated with “bathtub cheese” (i.e. Mexican-style Queso Fresco made illegally at home) made from raw milk, and raw fluid milk. Queso Fresco is inherently more dangerous than raw milk, and is associated with more serious outbreaks and illnesses. Again, this distorts the data and makes raw milk seem more dangerous than it really is. (Note: commercial, properly aged raw milk cheese has never been implicated in a disease outbreak.)

(For a more detailed analysis and critique of the CDC report, see this article from the Weston A. Price Foundation.)

In light of these weaknesses, I decided to conduct my own analysis using a more comprehensive data set including the CDC foodborne disease outbreak surveillance tables, an online outbreak database published by the Center for Science in the Public Interest (CSPI), public health reports such as the Morbidity and Mortality Weekly (MMWR), a CDC line list produced in response to a Freedom of Information Act (FOIA) request to CDC by the Farm to Consumer Legal Defense Fund (FTCLDF), and peer-reviewed studies in the scientific literature (2,3,4).

I purposely excluded outbreaks associated with Queso Fresco cheeses, because we are concerned here with the safety of raw milk and not raw cheese made in a bathtub, which I would never eat and would never advise anyone else to eat. I chose to focus on the most recent data available, from 2000 – 2007, since unpasteurized milk consumption increased significantly over the last decade.

I also included two notable outbreaks in California that were missing from both the CDC and CSPI databases: a large outbreak of campylobacteriosis in 2006, involving over 1,644 illnesses among prison inmates that was linked to pasteurized milk produced by an on-site prison dairy and another campylobacteriosis outbreak in 2007, that caused 8 illnesses following consumption of commercial raw milk and/or raw colostrum. (5,6)

What does this more reliable, peer-reviewed dataset tell us about the safety of raw milk?

The chart below lists all outbreaks and illnesses associated with unpasteurized milk from 2000 − 2007. Click the link to display the chart.

Raw milk data

There were 37 outbreaks and 800 illnesses from unpasteurized milk during from 2000 − 2007, with an average of 100 illnesses per year. The estimated U.S. population as of today is approximately 313,500,000. Using the CDC’s own 2007 FoodNet Survey data indicating that 3% of the population consumes raw milk, we can estimate that approximately 9.4 million people drink unpasteurized milk (as I said above, the number is likely higher because of the explosive growth in the popularity of raw milk over the past 5 years, but 2007 is the latest reliable estimate we have).

This means you had a roughly 1 in 94,000 chance of becoming ill from drinking unpasteurized milk during that period.

Now let’s compare this to pasteurized milk, as the CDC did in their study. The chart below lists all outbreaks and illnesses associated with pasteurized milk from 2000 − 2007. Click the link to display the chart.

Pasteurized milk data

There were 8 outbreaks with 2,214 illnesses, with an average of 277 illnesses per year. According to the CDC FoodNet survey, 78.5% (246,097,500) of the U.S. population consumes pasteurized milk.

This means you had a roughly 1 in 888,000 chance of becoming ill from drinking pasteurized milk.

According to these data, it’s true that you have a higher chance of getting sick from drinking raw milk than pasteurized milk. But the risk is 9.4 times higher, not 150 times higher as the CDC claimed.

Perhaps this is a good time to review the difference between absolute and relative risk. When you hear that you have a roughly 9 times greater (relative) risk of getting sick from drinking raw milk than pasteurized milk, that might sound scary. And indeed it would be, if we were talking about the absolute risk moving from 5% to 45%.

But when the absolute risk is extremely small, as it is here, a relative 9-fold increase is rather insignificant. If you have a 0.00011 percent chance of getting sick from drinking pasteurized milk, and a 9.4 times greater risk of getting sick from drinking unpasteurized milk, we’re still talking about a miniscule risk of 0.00106% (one one-thousandth of a percent).

But to truly gauge the risk, we should ask how serious these illnesses are.

An “illness” in these data can mean everything from an upset stomach to mild diarrhea to hospitalization for serious disease.  One of the reasons most foodborne illnesses go unreported is that they are only a passing nuisance.

When is the last time you had a bout of diarrhea that you suspect was caused by something you ate?  Did you report it to your doctor or the county public health department?  Probably not.

The statistic we should be more concerned with is hospitalizations for serious illnesses such as kidney failure and hemolytic uremic syndrome (HUS) caused by unpasteurized milk.  This does happen, and children and the elderly are particularly vulnerable and more likely to experience a serious illness.  That said, hospitalizations from raw milk are extremely rare.  During the 2000 − 2007 period, there were 12 hospitalizations for illnesses associated with raw fluid milk. That’s an average of 1.5 per year. With approximately 9.4 million people drinking raw milk, that means you have about a 1 in 6 million chance of being hospitalized from drinking raw milk.

To put this in perspective, according to the U.S. Department of Transportation, you have a roughly 1 in 8,000 chance of dying in a motor vehicle accident if you live in the U.S..  Therefore, you have a 750 times greater chance of dying in a car crash than becoming hospitalized from drinking raw milk.

The risk of dying in a plane crash (1 in 2,000,000) is orders of magnitude lower than dying in a car accident (1 in 8,000) – and yet most people who are afraid of flying don’t hesitate to get in their car. But as unlikely as dying in a plane crash is, it’s about 3 times more likely than becoming hospitalized (not dying) from drinking unpasteurized milk.

As I said earlier in the article, there has not been a single death attributed to drinking unpasteurized milk since the mid-1980s. There were 5 stillbirths attributed to an outbreak linked to bathtub-style Queso Fresco in 2000 in North Carolina. These were the only deaths during the 2000 − 2007 period I analyzed.

How does the risk of drinking raw milk compare to other foods?

Now let’s put some of these abstract numbers into perspective.

According to the CDC Morbidity and Mortality Weekly (MMWR), from 2006 − 2008 there were an average of 13 outbreaks and 291 illnesses per year associated with shellfish and mollusks. According to the CDC FoodNet Survey, about 5.7% of the population (17,869,500) consumes shellfish. This means you had a roughly 1 in 61,000 chance of becoming ill from eating shellfish. That’s about 1.5 times the risk of becoming ill from drinking raw milk (1 in 94,000).

The risk is even greater – and more serious – if you eat raw oysters. 7.4% of people who eat oysters consume them raw (1,322,343). There are 15 deaths a year on average attributed to raw oyster consumption. This means you have about a 1 in 88,000 chance of dying from raw oysters. In other words, you have a greater chance of dying from eating raw oysters than you do of getting sick from drinking unpasteurized milk.

What about other more commonly eaten foods?  Check out the chart below, from the 2008 CSPI report. It shows the relative incidence of foodborne illness from 1999 – 2006, adjusted for consumption.

As you can see:

  • Seafood caused 29 times more illnesses than dairy
  • Poultry caused 15 times more illnesses than dairy
  • Eggs caused 13 times more illnesses than dairy
  • Beef caused 11 times more illnesses than dairy
  • Pork caused 8 times more illnesses than dairy
  • Produce caused 4 times more more illnesses than dairy
What this chart clearly shows is that when it comes to foodborne illness, dairy should be the least of your concerns.

I hope this helps you understand the true risk of drinking unpasteurized milk within the context of other risks most of us take on a daily basis without a second thought.  Of course, the next question that naturally arises is why someone might be willing to take any additional risk with raw milk – however miniscule it is on an absolute basis – when pasteurized milk is readily available.

In Raw Milk Reality: Benefits of Raw Milk, I’ll address that question by exploring the benefits of raw milk from a variety of perspectives.

597 Comments

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  1. I find it surprising that people think drinking milk (raw or not) is anything but processing something. Milk has evolved to be drunk immediately after it is produced, not held, not chilled so as soon as you put raw milk into a bottle, you are changing it, processing it and giving pathogens a chance to grow.

    Your note, “commercial, properly aged raw milk cheese has never been implicated in a disease outbreak” is untrue. There have been several outbreaks (Errington Cheese in Scotland is a recent case).

    Making it clear what you mean by “properly aged” would also be useful. You could mean “under proper hygienic conditions” or you could mean “matured for over 6 months” for example.

    Hard cheeses made with raw milk like some vintage cheddars, parmesan, I agree, your risks are tiny. Soft or mouldy cheeses like brie or unpasteurised blue cheese, the risks are much higher. This is because the cheese making process may stop the growth of the pathogens but when the mould starts to grow the pH returns closer to neutral meaning that pathogens present are likely to grow. In hard cheeses the competing microflora, time, low water activity and lower pH should all help reduce the risk.

    I know of a retailer who tested loads of raw milk samples a few years back and came up with a result of 10% failure for Listeria monocytogenes. I would not take those odds, especially with the young, elderly, sick or pregnant. Farmers can do things to make sure their milking parlours are clean but fundamentally they cannot completely exclude the risks of pathogen contamination, (particularly coliforms from the guts of the cattle.) I know how hard it is to keep a high risk or high care factory clean and while I have huge respect for farmers, I would not trust a farmer to be knowledgeable enough to know how to do this and even after 20 years in the food industry myself, I’m not sure it’s even possible.

    I concede that our food industry has probably become too sterile and our gut microflora have probably been impacted as a result but I would say there are better and safer ways to improve your health and gut microbiome diversity like eating more fruits and vegetables.

    Right now I would say the knowledge of farmers and regulators is insufficient to know whether this is being done safely (or can ever be done safely). I’d also say there is weak evidence at best that raw milk is of any health benefit. I’m not saying never but I would urge people to hold off for now. Don’t treat science like a lawyer. You don’t look at scientific evidence and look for the one piece of information which introduces “reasonable doubt”, you should look at scientific evidence and look for where the weight and consensus is. Right now, the weight and consensus is behind pasteurised milk being safer and raw milk being unsafe especially for vulnerable groups with weakened immune systems. One or two studies / anecdotes have shown things aren’t quite so bad but that will be very much dependent on the skill and knowledge of microbiology of the farmer. Knowing many farmers as I do, seeing how somatic cell counts can vary by farm, season etc, I can tell you that is not a risk I would take.

  2. Did anybody realize this guy threw in an unconfirmed outbreak for pasteurized milk? He says that pasturized milk had 8 outbreaks and 2400+ illnesses. BUT, the single unsubstantiated outbreak he throws in accounts for 1600+ of these.

    In statistics, a single data point that accounts for the vast majority of events HAS to be thrown out as an outlier. You simply cannot have meaningful statistics that tell any truth about “typical” rates when a one-off big event throws the numbers off.

    The bigger story is that pasteurized milk had ONLY 8 outbreaks. Considering how many more producers there are than for raw milk, this means a lot.

    And then raw milk had 37. which for the very few raw milk producers means that something is way off.

    Raw milk remains the most dangerous ready to eat food out there. Don’t let an activist feigning even handedness pull off this slight of hand to say otherwise

    • Your observation about a single data point with a large number is noted and valid. However, this does not influence the raw milk data. The raw milk data tells a more convincing story regarding overall risk. In addition, If you subtract the 1600 cases that were not included in the CDC data you would be left with an actual number of about 600. This would of course make the CDC numbers more favorable in terms of lower rates of illness with pasteurized milk. Of most concern is the fact there is no reason given as to why the campylobacter outbreak was excluded from the CDC data in the first place. There may be a valid reason (such as the fact that an isolated/concentrated population is not representative of the general population). I examined the specifics of the prison campylobacter outbreak here: http://outbreakdatabase.com/details/california-state-prisons-spoiled-milk-2006/
      Although it is possible that the campylobacter outbreak occured from some other source (poultry), it is not likely based on the specifics sited in this report. In conclusion, it seems to me that common sense should be employed here. Individuals who have compromised immunity or are susceptible to other illnesses (including the very young and old) should consider avoiding raw milk. The consumption of raw milk by healthy individuals with robust immune function posses little serious risk compared to other sources.
      VStanger

      • I don’t have a problem with including the outbreak due to the fact that milk was the likely source of infection. I’d concede it. Many raw milk outbreaks don’t get 100% confirmed and it’s not always simple to get a legit sample after the fact to get 100% confirmation. We have to accept the probable cause either way.

        I just think counting illnesses is a poor way to figure out how often contamination occurs. You would not need to do outlier tests the same way if you weren’t counting illnesses, but counting individual outbreaks.

        Technically this would probably identify the hazard more than the risk, but it would give an apples to apples look at what the risk would be if raw milk had the consumership and quantity of producers that other common foods have.

        Individual outbreak numbers tell the real story:

        The reality is that as the 2006 pasteurized milk incident shows, a product with a large distribution an broad consumer base can have a large illness count from a single incident. Same will often be true for poultry etc.

        Just for fun, pretend like raw milk had the same consumer base that pasteurized milk has. Then figure out how many people would have been affected. For fun lets say there are 100 producers of pasteurized milk in the country, and 5 producers of raw milk. Then our numbers for our fictitious world would be:

        Raw milk outbreak= 37/3 -> oubreaks per producer is 28
        Pasteurized milk outbreaks=6/100 -> oubreaks per producer is 0.06

        These are fake numbers. I don’t know if we have 3 raw milk producers for every 100 pasteurized milk producer, but I wouldn’t be surprised if it’s somewhere in that neighborhood. I could be off by a lot and still show that the oubreak/producer count for raw milk is unacceptably huge compared to pasteurized.

        This then doesn’t even take into consideration batch size and batch counts. The small consumers likely have far smaller and fewer batches. So doing the same calculations on outbreaks per batch which is the REAL way to normalize something like this. Think about it, if a raw milk producer produced one batch per year, than yearly statistics are meaningless.

        To get real about “riskier” foods than raw milk, let’s also not neglect to factor in mishandling and undercooking. Nearly all of the sicknesses from the meats and seafoods listed would be attributed not to intrinsic risk, but to the fact that you need to properly cook most meats to make them safe to consume.

        Now do the same for raw milk, and you’ll quickly realize that Mr. Kessers decision to throw out “bathtub” cheese is illegitimate, at least by comparison. If you intend to use raw milk as an ingredient for cheese, you must handle it properly much like not leaving raw chicken out in the sun for hours before you cook it. If you don’t want to include such preparations, you are forced to only compare raw milk against other ready-to-consume products. Maybe oysters or sushi-grade fish, produce etc.

        The point is Chris Kesser used methodology that seems to tell the story, but really does not. Looking at proper metrics that tell you how often problems really occur, and what that would look like at-scale and per capita…well the picture is bleak.

        When the smoke clears, raw milk is the clear loser. Highest risk, zero tangible benefits. The only argument that I can agree with is that you should accept the risk if you like the way it tastes. But then charatans like Chris Kesser should not be trying to deflate the risks with illegitimate analysis and unsubstantiated “benefits”.

  3. Great science based article comparing raw and pasteurized below. If you don’t have time (or a short attention span) focus on pages 18 and 19. In the end it is a risk vs benefit and I agree with the JHSPH that the proven benefits of raw are small at best but the risks are real. Don’t let anecdotes like “I drink raw every day and I’m great” become the “science” you make decisions based on.

    http://www.jhsph.edu/research/centers-and-institutes/johns-hopkins-center-for-a-livable-future/_pdf/research/clf_reports/RawMilkMDJohnsHopkinsReport2014_1208_.pdf

    https://sciencebasedmedicine.org/raw-milk-in-modern-times/