Is drinking raw milk more dangerous than drinking pasteurized milk?

Question

In Australia "raw milk", more commonly known as un-pasteurised milk, is mostly illegal for human consumption, except in one state, I do believe. The consensus appears to be that pasteurising the milk makes it safer to drink, but many argue (mostly farmers and a few scientists) that raw milk is safe to consume.

There are many arguments and claims, but from what I've read pasteurised milk has caused more bacteria poisoning scares than un-pasteurised milk. People that grew up on a farm or still live on a farm have been drinking un-pasturised milk for decades and seem to have remained in good health.

Is drinking raw milk really more dangerous than drinking pasteurised milk?

Answer 1

EDIT 2013/05/21

The CDC recently released statistics for the first time on raw milk consumption, and raw milk-related illnesses. They also released their own conclusions, which, ironically, don't match their own data. However, an article released a couple weeks ago, Raw Milk Reality: Is Raw Milk Dangerous? attempts to examine the best numbers available from the CDC and other sources, and does its own analysis of the relative safety of raw milk compared to other foods, and specifically, pasteurized milk.

Among its findings:

• Dairy products, categorically, are the safest of all food types, in terms of food-borne illness outbreaks
• 2000 - 2007, there were 37 food-borne illness outbreaks related to raw liquid milk, affecting 800 people. Average outbreak size: 22 people
• 2000 - 2007, there were 8 food-borne illness outbreaks related to pasteurized liquid milk, affecting 2214 people. Average outbreak size: 277 people
• 2000 - 2007, raw liquid milk was responsible for an average of 100 reported illnesses per year among an estimated 9.4 million consumers of raw liquid milk, for a 1 in 94,000 chance of becoming ill
• 2000 - 2007, pasteurized liquid milk was responsible for an average of 277 reported illnesses per year among an estimated 246.1 million consumers of pasteurized liquid milk, for a 1 in 888,000 chance of becoming ill
• 2000 - 2007, raw liquid milk was responsible for 12 hospitalizations, or 1 in 6 million chance of being hospitalized due to raw liquid milk consumption

The article also pulls in data from other sources to compare the relative risk of raw milk consumption with other common activities, and concludes that:

• Drivers are 779 times more likely to die in a motor vehicle accident than raw milk drinkers are to be hospitalized for consuming raw liquid milk
• Air passengers are 3 times more likely to die in an aircraft accident than raw milk drinkers are to be hospitalized for consuming raw liquid milk

Another recent article, Outbreaks and Illnesses from Raw and Pasteurized Milk And Dairy Products, 1998-Present looking at data over a longer time period, but for which absolute number of raw-milk consumers is not available. It shows that, for liquid milk consumption:

• 1998 - 2009, there were 85 food-borne illness outbreaks related to raw liquid milk, affecting 1,495 people, including no deaths. Average outbreak size: 18 people
• 1998 - 2009, there were 9 foud-borne illness outbreaks related to pasteurized liquid milk, affecting 2,200 people, including 3 deaths. Average outbreak size: 244 people

The data from these two articles don't completely agree with each other. It's not clear where the discrepancy lies. What seems clear from my research, though, is that there has not been a single confirmed raw-milk releated death in the U.S. since the 1980s, despite CDC claims to the contrary on their web site. The CDC has even admitted their propaganda is wrong.

TL;DR; / Conclusion:

Using the best data currently available, strictly from a food-borne illness standpoint, consuming raw milk carries roughly 9.4 times higher relative risk than consuming pasteurized milk. But in absolute terms, both risks are incredibly small, with raw milk carrying a 1/94,000 (0.001064%) chance of illness, and pasteurized milk carrying a 1/888,000 (0.000113%) chance of illness.

For many, the touted benefits of raw milk (more on that in my old answer below) are worth the added 0.000951% chance of food-borne illness.

But food-borne illness is not the only risk associated with liquid milk consumption. Some other possible risks which may favor raw milk, but which are much harder to quantify, are:

• Pasteurized milk may contribute to many ailments, including lactose intolerance, allergies, asthma, frequent ear infections, gastro-Intestinal problems, diabetes, auto-Immune disease, attention deficit disorder and constipation (source).
• Traditional dairies in the U.S. use rBGH (which is illegal in many other countries). Consuming milk from rBGH-treated cows may increase the risk of certain cancers in humans, particularly breast and prostate cancer. (source)
• Traditional dairies, and in particular those which also use rBGH, often administer large amounts of antibiotics to their cows, which typically gets into the milk, exposing the human consumers to unnecessary antibiotics. The risks of over-exposure to antibiotics is well documented. The main concern is in making antibiotic-resistent "superbug" strains. (source).

Note that the last two (rBGH and antibiotics) can also be avoided by purchasing organic pasteurized milk.

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MY OLD ANSWER; left for reference

Short answer: No. In fact, pasteurized milk is often more dangerous than raw milk.

Long answer: Of course, it depends.

Raw milk is not inherently dangerous at all. The reason for pasteurization is not because milk is, by nature, a dangerous product to consume. Pasteurization is done for two basic reasons: 1) To kill any living contaminants, and 2) to extend shelf life.

Because pasteurization kills most bacteria (good and bad) contained in the milk, it won't go bad as quickly. The down side to this is, when it does begin to sour, it goes rancid, and is no longer fit for human consumption. On the other hand, when raw milk begins to sour, it isn't actually "bad" immediately, because the live cultures in milk prevent it from going rancid so quickly. Many foods we take for granted are various forms of "sour" milk--Yogurt, Cheese, sour cream, etc. And if you consume raw milk, and it begins to sour, you can still use it to make many of these milk products.

Fermentation starts digesting the milk protein casein, and digests some of the lactose. Souring of [raw] milk does not destroy any of milks beneficial properties.

Treat a sample of pasteurized milk in the same way as above and putrefaction will make the milk unfit for human consumption. This is due to disease producing bacteria surviving the pasteurization process. (Emphasis in original)

And paraphrasing an Anonymous dairy farmer:

Pasteurized milk gone bad will kill you - raw milk won't.....pasteurized milk rots.

Now, the reason for pasteurizing milk is to kill harmful living organisms. However, it also kills most of the beneficial living organisms in the milk as well. This can, in some cases, actually lead pasteurized milk to be more dangerous than raw milk.

• Pasteurized milk is harder to digest, especially for those who are lactose intolerant or with digestive disorders.

  Today, milk is made even more indigestible by the universal practice of pasteurization, which destroys its natural enzymes and alters its delicate proteins. (source).

• Pasteurized milk has less nutritional value. (source)

• Pasteurized milk is less beneficial in boosting immune system function (source)

• Pasteurized milk is more susceptible to contamination:

  Due to high-volume distribution and its comparative lack of anti-microbial components, pasteurized milk when contaminated has caused numerous widespread and serious outbreaks of illness, including a 1984-5 outbreak afflicting almost 200,000 people. In 2007, three people died in Massachusetts from illness caused by contaminated pasteurized milk (Real Milk PowerPoint, slide 30).

• Raw milk is useful in fighting infection, diarrhea, rickets, tooth decay, TB, asthma, allergies (source), diabetes¹, Bright's disease, gastric disturbances, obesity, urinary problems, and kidney stones²

• Pasteurized milk contributes to many ailments (ironcially, many of them are also found in the list that raw milk helps treat): lactose intolerance, allergies, asthma, frequent ear infections, gastro-Intestinal problems, diabetes, auto-Immune disease, attention deficit disorder and constipation (source)

The reason pasteurization ever caught on as a practice, was to reduce the possibility for contamination in milk. This may well have been (and may continue to be!) a valid concern, in some cases. Although the evidence is shaky, at best. The two possible sources of contamination are:

1. Contamination passed from cow to milk

   As @Paula pointed out, there has been a concern that TB may pass from bovine to human. This was considered a legitimate threat in 1882, when Dr. Robert Koch discovered that bovine and human varieties of TB were deemed similar. However, Koch later changed his opinion, saying that bovine TB could not spread to humans. The professional opinion has further been adjusted since then, and the current state of affairs on bovine/human TB contamination is essentially that:

   [I]t appears obvious that we have arrived at a point in [the United States] when the dissemination of bovine tuberculosis is no longer a matter of serious concern. (source).

   Ironically, raw milk is actually beneficial in fighting TB in humans. Real Milk PowerPoint, slides 54-56, 58.

2. Contamination from processing

   At the time pasteurization was initiated, many (if not most) of the dairies in the U.S. (and much of Europe) were filthy, and sanitation was abysmal, leading to much contamination of milk during milking and bottling. Since the invention of closed-system milking machines in the 1940s, it is possible to eliminate the most serious exposure to external contamination.

Other factors affect the relative safety of raw vs. pasteurized milk as well. This site describes how a cow's diet has a strong impact on the pathogen-fighting ability of the milk produced, and as such, milk from cows fed diets heavy in heavy in grain, soybeans and cottonseed meal (common in many commercial dairy operations) must be pasteurized to be safe.

On the measured safety of raw milk:

• Found here:

  Based on data in a 2003 USDA/FDA report: Compared to raw milk there are 515 times more illnesses from L-mono due to deli meats and 29 times more illness from L-mono due to pasteurized milk. On a PER-SERVING BASIS, deli meats were TEN times more likely than raw milk to cause illness (Intrepretive Summary – Listeria Monocytogenes Risk Assessment, Center for Food Safety and Applied Nutrition, Sept. 2003, page 17). (Emphasis mine)

• This 132-page report examines the various scientific studies that supposedly cast a shadow over raw milk, and tries to interpret them with less (supposed) bias. The following table is taken from page 6, and shows the results of examining 70 studies purported to show the dangers of raw milk, and the various flaws in many of the reports. The paper goes on to address each of the 70 studies point-by-point.

  

  Among the findings of this report are that much of the evidence cited in the BJM article mentioned in @matt_black's answer, was flawed. Specifically, those that are mentioned in both papers:

  • BJM Ref 1, Review p.80 - Milk-bourne illness outbreak in Scottland likely would not have been averted by pasteurization
  • BJM ref 8, Review p.43 - Testing found no contamination in the raw milk supply
  • BJM ref 10, Review p.41 - Contaminated raw milk was discovered, but not in milk intended for sale as raw milk.
  • BJM ref 12,18, Review p.42 - "This is a review rather than a primary reference." and "There are no outbreaks mentioned in this review that could be said to be conclusively linked to unpasteurized milk, and in most cases the suspected milk was intended for pasteurization."

• 100% of the studies cited by the FDA to implicate raw milk were fatally flawed, and failed to show raw milk is dangerous. (Response to the FDA, p. ii)

• Between 1980 and 2005, the CDC attributed 19,531 illness cases to pasteurized milk and milk products, 10.7 times more than to raw milk. From this we cannot determine if raw milk is safer than pasteurized, in part because there are no accurate estimates of raw milk consumers. ([Response to the FDA, p. ii)

• Between 1998 and 2005, raw milk was associated with 0.4% of CDC-documented food-borne illnesses, including 831 illnesses, 66 hospitalizations, and a single death. (Response to the FDA, p. iii,5) Clearly raw milk is not "perfectly safe," but neither is any other food.

In conclusion, if you can find a clean source of raw milk from healthy, well-fed cows, it is probably safer than the pasteurized milk you can find at the supermarket. On the other hand, if your raw milk is unsafely handled, or comes from unhealthy cows, it may be harmful. But that's really just common sense--we all want to eat clean food, right? And as many others have pointed out, enforcing proper quality control on raw milk can be very difficult--although it has been done in many large-scale commercial operations, but usually along with a higher price tag.

_{1 Porter, Charles Sanford. Milk Diet as a Remedy for Chronic Disease. Long Beach, California, 1905
2 Professor Tyson, James. Journal of the American Medical Association. June, 1884.}

Answer 2

There has been a similar debate in the UK (for an argument in favor see here). Moreover few doubt that unpasteurised milk tastes much more pleasant and it may even be more nutritious (for the nutrition argument see here). Beware, though, of some of the positive health claims made by the "raw milk" movement as they smack of the lack of skeptical analysis common in many "natural is best" arguments.

So the reason why some government restrict supply isn't because raw milk is bad. The problem is the small risk of serious food poisoning that is easy to reduce to nearly zero with pasteurisation. So most people who consume raw milk will get taste and possibly (marginal) health benefits, but, occasionally, people will die from an avoidable cause of food poisoning. The evidence is presented in this BMJ article. And here are some selected quotes from it. First from the summary (my highlights):

Infections carried in milk, particularly salmonellosis and campylobacter enteritis, have continued to feature in Great Britain in recent years. Less commonly reported infections included an outbreak in 1984 in England due to Streptococcus zooepidemicus, in which 12 people, eight of whom died, were admitted to hospital.

The implementation of legislation in 1983 requiring heat treatment of cows' milk for sale to the public reduced the incidence of milkborne infection in Scotland compared with previous years and compared with England and Wales, where, without legislative control, outbreaks continue to occur.

Some snippets of evidence from the article:

Twenty outbreaks of milkborne salmonellosis affecting at least 518 people were reported [in scotland] during 1983-4; in 19 raw milk was implicated...

Twelve of the outbreaks in 1983-4 affected consumers in the general community who had purchased untreated milk from local producer-retailer dairy farms; the two largest outbreaks affected 182 and 106 people respectively. The remainder affected people living in dairy farming communities who had been drinking raw milk from their own herds...

The most notable event attributed to consumption of raw milk during the past two years was an outbreak of Streptococcus zooepidemicus; of 12 people admitted to hospital, eight died...

So there are risks which are not common, but are serious when they occur. Most people who drink raw milk will never experience them, but if you are going to choose to drink it you probably should do so knowing the small probability of danger.

EDIT Summary of more recent USA experience from this paper (my emphasis):

Eighty-three fluid milkborne outbreaks were reported between 1990 and 2006, resulting in 3621 illnesses. The mean number of illnesses per outbreak was 43.6 (illness range: 2-1644). Consumption of unpasteurized milk was associated with 55.4% of reported outbreaks.

Give that other estimates of milk consumption suggest that raw mile is <1% of total volume, this suggests it is between 50 and 100 times riskier.

Edit april 2014 Visual.ly has compiled a useful infographic on the statistics on raw milk. It is big but useful:

It is worth noting that it also addresses some of the spurious positive claims for raw vs pasteurised milk (such as the ridiculous claim that pasteurisation causes lactose intolerance).

Answer 3

When discussing raw milk and pasteurization it is important to remember that one of the reasons to introduce pasteurization was to combat disease, especially TBC:

The bacillus causing tuberculosis, Mycobacterium tuberculosis, was identified and described on March 24, 1882 by Robert Koch. He received the Nobel Prize in physiology or medicine in 1905 for this discovery. Koch did not believe that bovine (cattle) and human tuberculosis were similar, which delayed the recognition of infected milk as a source of infection. Later, this source was eliminated by the pasteurization process. (Wikipedia)

I don't know if this is still a valid reason to pasteurize milk, but it seems like a small price to pay.

(I know Wikipedia is a bit frowned upon here, but the article seems well referenced. The link between milk and TBC used to be common knowledge, but since we no longer have to worry about infected milk people have forgotten.)

Answer 4

(as pointed out by @David in the comments above)

It is important to clarify the comparison. On one hand, it appears that store bought pasteurized milk is safer than farm bought raw milk. However, this may be due to the fact that farm bought milk is not subjected to the same regulations as store bought milk. Indeed, in many states, raw milk is sold as 'pet food' to circumvent regulations intended to protect public health.

To the consumer, it is important to understand the risks associated with milk processing and distribution.

For example, the Centers for Disease Control provide an extensive warning against raw milk, in which they also state:

Pasteurized milk products have occasionally caused illnesses and outbreaks. Usually, this has happened because of germs introduced in the dairy after the pasteurization process. Pasteurized milk that is correctly handled in the dairy, bottled, sealed, and refrigerated after pasteurization, and that is properly handled by the consumer, is very unlikely to contain illness-causing bacteria. Considering the amount of pasteurized milk consumed in the United States, illness from it is exceedingly rare.

However, there is a notable lack of evidence available to compare the danger of pasteurized vs unpasteurized milk that have passed similar regulatory testing prior to sale. One of the largest producers and commercial sellers of raw milk presents the (apparently unpublished) results of tests for pathogens that indicate they have never found dangerous levels of pathogens in their milk (one exception being outsourced milk that they used for cheese, but in this case they did not used the contaminated milk).

Answer 5

Is drinking raw milk more dangerous than drinking pasteurized milk?

The answer is yes. The reason is that raw milk potentially has more harmful bacteria than pasteurized milk. Getting rid of potentially harmful bacteria is the main reason we started pasteurizing milk.

Now, there are two parts to this. What bacteria and their amount, and how harmful the potential infection will be.

Even a very carefully managed farm may occasionally find potentially harmful bacteria in the milk. Unless every batch is monitored before consumed you cannot really be sure. Among the more harmful bacteria that might be found are tuberculosis (Mycobacterium tuberculosis), EHEC (several species of E. Coli), Salmonella, Listeria and so on. When pasteurizing the milk, these bacteria are killed. If the raw milk is free from these disease creating bacteria, you will of course not get sick from them.

The second part is how sick you will get from the bacteria. This is dependent to a large part to your general health state and also to how well your immune system is able to cope with the infection. An healthy adult ingesting EHEC bacteria might get a diarrhea and recover in a day, a sickly elder person might die.

Another example is tuberculosis. In older times this was a chronic disease that could not be eradicated from the body and a common cause for premature death. In modern times, a regime of various antibiotics has made this disease look harmless. But lately the world has seen strains of totally drug resistant TBC WHO as of July 2018 uses the term extensively drug resistant. The risk of you contracting this from raw milk in "western societies" is very low, maybe non-existent. But I would not bet on that being the same in every farm the world has.

So, yes, you take you chances drinking raw milk. Admittedly, the risk is very low but to answer the question: "drinking raw milk is more dangerous than drinking pasteurized milk", the answer is yes. But always remember, that risk (or chance) is a number between 0 and 1 (from cannot ever happen up to will happen every time). In this case it takes two numbers to become sick, you need to receive the bacteria in suffixet number and your immune system needs to not be able to handle the infection.

References: Swedish health authority Livsmedesverket

Opastöriserad mjölk benämns ofta "mer naturlig" och därför extra bra för hälsan. Men det är stor risk att opastöriserad mjölk sprider olika bakteriesjukdomar. De är särskilt allvarliga för små barn, gravida, äldre och personer med nedsatt immunförsvar.

Google translate Opa-buttered milk is often termed "more natural" and therefore extra good> for health. However, there is a high risk that unastasted milk spreads differently> bacterial diseases. They are particularly serious for young children, pregnant,> elderly and people with impaired immune system.

The site goes on to describe infections due to Campolybacter and Ehec. (20 documented cases between 1994-2011, compared to zero for pasteurized milk)

Reference 2: PDF with report of literature search (on same page). Also lists specifics of the 20 dokumented cases mentioned above. enter link description here

Nonpasteurized dairy products, disease outbreaks, and state laws-United States, 1993-2006 (Note that the quote is out of context and shortened)

Nonpasteurized products caused a disproportionate number (≈150× greater/unit of product consumed) of outbreaks and outbreak-associated illnesses