Still want to drink raw milk?

 I hesitate to post this and it may offend some readers, but the message is, in my opinion, entirely valid.  And, hey, we microbiologists have to have a little fun every now and again.

https://youtube.com/shorts/CuSwN2CYylQ?si=DYigRj0-nNJ2Kcu1

 

To those who followed this yesterday, I'm sorry that the link was wrong.  This one should direct you to the intended short vid. 

Raw milk comments cause another minor furore

This time, a senior scientist has kicked over the beehive and created a minor furore.   Professor Nigel French FRS, Director of the New Zealand Food Safety Science and Research Centre, has stated in an interview that he would not drink raw milk, nor give it to his family.

In my opinion, he is correct in stating that even the most careful production of raw milk cannot avoid some contamination by cow faeces, which, of course, contain bacteria and viruses.  Some of these bacteria and viruses can cause serious human disease.  As a microbiologist, I am fully aware of the sensitivity of microbiological testing and can confirm Prof. French's comment that bacteria can still be present, even if the test shows negative.

Scrupulous cleanliness and attention to detail can reduce the chances of faecal contamination of the milk, but cannot eliminate the risk.  Since the beginning of the year, there have been two recalls of raw milk over fears of contamination by Campylobacter, a bacterium that can cause diarrhoea (frequently bloody), abdominal pain, fever, headache, nausea, and/or vomiting.  Occasionally, it can produce more serious symptoms requiring hospitalisation.

Reading the comments on the article, it is clear that the proponents of raw milk consumption will not be swayed by scientific facts, and it is their right to drink raw milk.  However, the New Zealand
Prime Minister's Chief Science Advisor Dr Peter Gluckman concluded: "The claimed health benefits of raw milk compared with pasteurised milk are for the most part not backed by scientific evidence, making the risk-benefit ratio very high for this food product ..."  

I have written about the hazards of drinking raw milk before (see the label Raw Milk) and the latest recalls simply confirm my opinion.  Many of the people commenting on the report are saying that they grew up drinking raw milk without problems.  What they appear not to appreciate is that our lifestyle has changed.  We don't collect our milk daily; children are coddled and protected from exposure to bacteria by the use of antibacterial soaps and cleansers, they don't go out to play in the dirt and often they are not exposed to farm animals.  In my opinion, their immune systems are less robust.  At the very least, children should not be fed raw milk - they have no ability to refuse it.  

The regulations surrounding sale of raw milk have been tightened considerably, including labelling and warnings on bottles.  Raw milk cannot be sold from health food stores and use-by dates must be printed on the packaging.  It is interesting to note that sales of raw milk are not permitted in Australia.

Putting the squeeze on raw milk

Many of you will know that I have written several articles on the dangers of consuming raw milk.  In my opinion, any perceived benefits are greatly outweighed by the real risks.

However, if you will permit me to mix metaphors, you can now have your cake and eat it.

An Australian company, Made by Cow, is offering raw milk processed by "cold pressure".  There are few details available, but it appears that the company is using an established process (High Pressure Processing, HPP) to make the milk as safe as pasteurised milk.  The process has been approved by the New South Wales Food Authority, and the product can be sold in stores.

The concept of killing bacteria by applying high pressure has been known for many years, (Hite studied the effects of pressure on bacteria in 1899), but practical machines to process food have been difficult to build and the processes have all been slow.  

Pressures of up to 6800 Bar (about 100,000 psi) held for several minutes are required to kill bacteria. Of course, there are many possible combinations of pressure, temperature and time, and whether the pressure is applied in a single treatment or is cycled several times.  However, the degree of inactivation appears to depend on the duration of the high pressure, and not the number of cycles.

The primary site of damage to the bacterial cell appears to be the cell membrane.  If this membrane is damaged, its permeability may be greatly changed, resulting in failure of respiration and transport functions, and hence death of the cell.  Spores are very much more resistant, so milk processed by pressure alone is unlikely to be sterile.  There are some changes in foods resulting from HPP - some enzymes may be inactivated, while others have their activity enhanced.  Other effects seen in foods are the gelling of some non-enzyme proteins and enhanced browning reactions at high pressure.  One assumes that the Made by Cow patented process has overcome these undesirable changes in the milk.

The major problem with current HPP is that the machines are batch processes, so throughput is low and the products are likely to be expensive.  However, if you are adamant that thermal pasteurisation damages the nutritional and functional properties of the milk, HPP milk may be the way to go.

Comment on potential hazards of raw milk consumption.

I was recently asked for comment on the tragic death of a youngster in Australia, apparently caused by consumption of raw milk.  I was given only 200 words to get the message across.  Rather than go over all of the arguments again, I have reproduced my comments below:

The recent tragic death of a 3-year old infant and serious illness of four other children in Australia is  yet another example of the risks associated with consumption of raw milk.

Proponents of the consumption of raw milk claim that this is a natural food and has been consumed for hundreds if not thousands of years.  That is true, but ignores the fact that many diseases can be transmitted from animals to humans in the milk.

The hazards of consuming raw milk have been known for a long time. In Ontario around 1900, over 10% of all childhood tuberculosis was thought to be caused by unpasteurised milk. The rate of tuberculosis infection and many other milk-borne diseases in children fell dramatically after enactment of a law in 1938 requiring milk to be pasteurised; this was hailed as a major achievement.

The fact is that between 1998 and 2005, a total of 45 outbreaks resulting in more than 1,000 illnesses, 104 hospitalisations and two deaths due to raw milk or soft raw milk cheese were reported to the US Centres for Disease Control and Prevention. 

There is some evidence that consumption of raw milk early in life can reduce the incidence of allergies.  Bacteria in the raw milk may transiently colonise the intestine, resulting in stimulation of the immune system through infection.  

In addition, when milk is digested, a variety of beneficial ‘bioactive peptides’ are released.  However, it should be noted that pasteurisation does not adversely affect the release of these peptides.

I have said this before and say it again:  Adults who decide for whatever reason to consume raw milk should consider the potential hazards and make an informed decision.  Children, who have no choice in the matter, should not be fed raw milk or soft raw milk cheeses.

The situation is a little different for hard cheeses, such as Parmesan, in which the conditions, or the process, are inhibitory to most pathogens.  Food Standards Australia and New Zealand has made the following determinations:

• Extra hard raw milk cheeses pose a low to negligible risk to public health and safety as survival and growth of Campylobactyer jejuni/coli, enterohaemorrhagic Escherichia coli (EHEC), Salmonella spp., Staphylococcus aureus and Listeria monocytogenes is very unlikely.

• The selected Swiss-type raw milk cheeses were all assessed as posing a low to negligible risk to public health and safety for the general population as survival and growth of C. jejuni/coli, E. coli (EHEC), Salmonella spp. and S. aureus is very unlikely. 

Note:  The FSANZ document is comprehensive and readers should consult the report for more detail. See:  http://www.foodstandards.govt.nz/code/proposals/documents/P1007%20PPPS%20for%20raw%20milk%201AR%20SD3%20Cheese%20Risk%20Assessment.pdf

•

Raw milk linked with food poisoning in New Zealand

I have written several times about the hazards of drinking raw milk (see the label "raw milk").  Using Ministry of Health information obtained under the Official Information Act, Talia Shadwell has written about food poisoning linked with consumption of raw milk in the Manawatu and Waikato, two regions of New Zealand.

A total of nine people, including two young children, were hospitalised in March, suffering from Escherichia coli  infection.  A month later, six people contracted campylobacteriosis.  A common factor in all these cases was apparently consumption of raw milk.

What is of great concern to me is that these patients revealed that they had little knowledge of the hazards of drinking raw milk, despite the publicity given to such outbreaks.

I would uphold the right of individuals to consume raw foods if they so wish, but they should be fully aware of the risks and remember that their children do not really have the luxury of food choice.

Poor Understanding - Raw Milk in New Zealand

Last week, I read an interesting article by Jill Galloway in the Manawatu Standard entitled "Selling milk as it was meant to be".  The story was about the increasing sales of unpasteurised and non-homogenised milk at the farm gate.  Unfortunately, the author and/or her interviewees made a number of errors.

Under New Zealand law, sales of raw milk from the farm gate have been permitted for several decades.  All other milk and milk products must be pasteurised or given an approved alternative treatment. Section 11A of the Food Act 1981 allows for producers to sell up to five litres of raw milk at any one time from their farm gates to people who intend to consume it themselves, or to provide it to their families.  However, the milk must be harvested under an approved Risk Management Programme under the Animal Products Act 1999.

So if farmers follow the rules, there should be no problem about safety.

However the article went on to express some strange views.

For example: "People believe in the integrity of food.  People want to know where it comes from. Processing destroys dairy products".

Or how about: (Farmers) "are up against rules, regulations and science".

But my favourite was:  "Before processed milk, there was no heart disease. Homogenisation means the fat particles are small enough to be ingested, not digested, and go straight through to the blood and arteries," Ms M. says. She thinks homogenisation began because people thought the fat on the top of milk was bad and they did not want to see it.

Hang on a minute.  If Ms M. is correct, then the dairy companies are actually delivering what consumers are demanding.

Second place goes to Farmer C: "When it is pasteurised, the milk becomes dead. People don't want to be eating or drinking dead stuff."

So you never had a steak, Mr. C?

I guess I should not poke fun at these people, who genuinely believe that their product is better than pasteurised milk.  And indeed, they are producing their product according to the NZFSA regulations.  But it does worry me that people can be so smart in some aspects of their lives but authoritatively make such ignorant statements.

Why do people buy insurance?

Do you sometimes think "Why do I keep paying insurance premiums for my car, boat, house, personal liability, camera etc?  I hardly ever make a claim".  In all the years I have been paying premiums, I have only once made a claim on my car insurance, and that was when one of the local semi-evolved simians stole it and drove it into a ditch.  Would you consider not insuring your house?  Would you be able to continue with business as usual if your offices burned down?  The chances of making a claim and getting some of the premiums back are quite small.

The probable reason we continue to pay is that it gives us peace of mind, knowing that if we do smash the car into a BMW or Rolls Royce, we won't be bankrupted by the repair bills for the other car.  We can drive, secure in the knowledge that we have that one covered.

Pasteurisation of milk is insurance and free.  A mild heat treatment kills all the pathogens that might have got into the milk during milking and transport, leaving the nutritional value essentially unchanged.  Why would you even consider drinking raw milk or eating raw cheese, knowing that there is a small chance that it could result in illness that would change your life or that of your family for ever?    There has been plenty written about the dangers of Escherichia coli O157:H7 and other STECs, so I'm not going to go over it again here.  (See other posts on E. coli by clicking the E. coli label at the RHS of this blog).

Please, this Christmas season, if you really want to eat and drink raw milk products, you can make an informed choice.  But don't give these products to children - they don't have that choice and a dose of E. coli O157:H7 can lead to HUS, which will probably ruin the rest of their lives.

Time for red faces? Perhaps raw milk is not all it's cracked up to be.

The last time I wrote a blog on raw milk, I received "fan mail" accusing me of being sensationalist and closed minded.  At risk of more unflattering comments, here is another post on the subject.

Proponents of raw milk consumption have long claimed health benefits of raw milk and products made from it.  One of those claims is that lactose intolerant individuals, who don't produce sufficient lactase in the small intestine, suffer reduced symptoms if they consume raw milk, rather than pasteurised.   

Stanford School of Medicine recently conducted a study of self-reported lactose intolerant individuals, who were given raw milk, pasteurised milk and soy milk in a randomized, double-blind, three-way crossover trial. This classic experimental design removes bias in experimenters and subjects.  If lactose intolerant individuals consume lactose (the sugar found in milk) they cannot break it down to glucose and galactose.  Anaerobic bacteria in the colon grow on the lactose and produce hydrogen, some of which enters the bloodstream and appears in exhaled breath.

The participants were tested for exhaled hydrogen on the first and last days of each 8-day exposure period.  There was no statistically significant difference between consumption of raw or pasteurised milk, but soy milk resulted in much smaller amounts of breath hydrogen.  Similarly, the symptoms reported - flatulence, abdominal cramping and diarrhoea - were the same for both raw and pasteurised milk.

The researchers reported that the results from their work, collected under standardised, controlled conditions, did not support the claim that, with respect to lactose intolerance, raw milk has benefits over pasteurised milk.

Meanwhile, raw milk and raw milk products continue to be linked with outbreaks of Escherichia coli and Listeria diseases

http://www.marlerblog.com/legal-cases/e-coli-and-listeria-in-raw-milk-and-cheese---growth-sectors-at-marler-clark/

Raw milk and people with influence

It’s happened again! Bill Marler quotes a Washington State Department of Agriculture News Release, reporting that three recent Escherichia coli infections in Washington have been linked to drinking raw, unpasteurised milk. The Washington state departments of Health and Agriculture have put out new warnings about the risks of consuming unpasteurised milk and milk products.

All the patients involved have reported drinking raw milk from the same supplier. Though no E. coli have been found in the most recent batch of product tested, the Washington State Department of Agriculture did find in the dairy the same strain involved in one of the illnesses.
Bill Marler, Doug Powell and I have all written on many occasions about the hazards of consuming raw milk. Doug has emphasized that personal freedom is all very fine, but young children cannot exercise freedom of choice. They are often the ones made ill by bacteria carried in raw milk. If you think that we are a bit over the top on this issue, have a look at the You Tube clip of Barb Kowalcyk talking about her son, Kevin, who contracted haemorrhagic E. coli infection.

http://www.marlerblog.com/2009/12/articles/legal-cases/perfectly-healthy-to-dead-in-twelve-days-hemolytic-uremic-syndrome/

A few days ago, Tamati Coffey was shown on TVNZ’s “Breakfast” programme milking a cow and then drinking the milk. No real problem there. The show’s hosts, Pippa Wetzell and Paul Henry then discussed the merits of drinking raw milk. Typically, Paul reckoned he wouldn’t touch the stuff, but I was surprised when Pippa, who recently had a new baby, argued that drinking raw milk is good for you. Many people watch this programme every day and there must be a proportion of those who are mothers of young children. Judging by the daily feedback, viewers hang on every word the presenters utter. I have to admit that I too enjoy the quick repartee of Paul and Pippa, but her throwaway line could easily influence parents to feed raw milk products to their children, with potentially disastrous consequences.

Perhaps television presenters should be a bit more careful when it comes to expressing views on the safety of foods – they are not trained in food safety. As they said in the post-war years when I was a lad “Careless talk costs lives”. It’s just as true today.

Coming soon to a store in New Zealand?

I have written several times about the potential hazards of consuming raw milk and raw milk products. Search this site using keyword “raw milk” for other posts.

Currently the New Zealand food regulations allow only three particular hard and very hard Swiss cheeses, extra-hard Parmesan style grating cheeses like Grana Padano, Pamigiano Reggiano, Romano, Asiago and Montasio and the semi-hard Roquefort cheese. Local manufacture of similar products is not permitted. See www.nzfsa.govt.nz/publications/media-releases/2008/2008-08-07-raw-milk.htm

The New Zealand Food Safety Authority is now asking for submissions on a proposed framework for the manufacture, importation and sale of raw milk products. See www.nzfsa.govt.nz?consultation

Aficionados of raw milk cheeses will applaud this move. It is quite possible to produce safe cheeses without pasteurization of milk and, provided that the resulting products are safe, manufacturers and consumers should be given the opportunity to make and taste them. However, the process requires strict control of animal health and rigorous processing hygiene - good regulations and inspection will be needed.

Even the cheesemakers are divided on the desirability of permitting the manufacture of raw milk cheeses. One, quoted in the Otago Daily Times on 11th August 2008 said that cheeses made from non-pasteurised milk could be “lovely", but they could also be “bloody awful stuff". The explanation for this is that pasteurized milk contains only heat resistant bacteria, such as some Streptococcus species and sporeformers. The cheese is made by inoculating the pasteurized milk with known cultures of "starter bacteria", which will produce lactic acid to coagulate the milk protein and produce a curd. When cheese is made from unpasteurized milk, the bacteria present in the raw milk may grow beside the starters. This can result in more complex flavours, but can also lead to variation between batches. Unfortunately, the non-starter bacteria can sometimes cause disease, such as salmonellosis and campylobacteriosis, or may produce toxins, such as staphylococcal enterotoxin.

Softer raw milk cheeses represent a greater risk to the consumer because of their higher water activity, which allows some pathogens to survive and grow. Control over the milk production and handling and the cheesemaking process itself must therefore be absolutely spot-on for these products.

Under the proposed framework, raw milk products would be categorised according to the risks they present. Category one products would pose no greater food safety concerns than pasteurised cheeses, such as Parmesan-style raw milk cheeses. Category two products would pose a low risk for the general population but vulnerable consumers with reduced immunity might be at greater risk. Products in this category would include semi-hard Roquefort. Category three would cover those raw milk products that cannot currently be produced to an acceptable level of safety for the general population. (As far as I know, this category has not yet been defined more closely).

Assuming that the consultation process approves the proposed framework, locally produced raw milk cheeses and other raw milk products may soon hit the delicatessen and specialty store shelves. It may be too soon to expect these products to be sold in supermarkets.

Would I eat raw milk cheese? Probably not until the framework were shown to be working well and the suppliers had built up a record of selling safe products. Even then, I would eat only the hard or semi-hard varieties. Would I give it to my little granddaughter? Not a chance! Raw milk products are not for little children or the immunocompromised.

Tuberculosis and Mexican cheese

Quite by chance, on the day I was writing my last blog article on raw milk, the Orange County Register published an article by Doug Irving on an outbreak of tuberculosis in San Diego. See http://www.ocregister.com/ocregister/homepage/abox/
article_2060722.php?orderby=TimeStampDescending&showRecommended
Only=0&oncommentsPage=2#slComments

Mycobacterium bovis is relatively rare in humans, but can be serious and difficult to treat. It is thought that the disease jumped from cattle to humans somewhere between 8000 and 4000BC, when cattle were domesticated. There is archaeological evidence that humans suffered the disease, pulmonary tuberculosis, which may have been contracted through consumption of raw milk. The human specialized form M. tuberculosis was probably spread by migrating Indo-Europeans and by 1000BC it had spread to the whole of the known world.

It appears that in the San Diego area, the disease is spreading primarily through the Latino population and scientists there believe that it may be being brought into the country from Mexico in queso fresco, a popular soft crumbly cheese that may be produced as a cottage industry.

The article in the OC Register contains some inaccuracies. Not all milk sold in the USA must be pasteurized; it depends on the particular State legislation. In addition, the article implies that the outbreak has suddenly flared. However, the actual study by UCSD Medical Center and county health officials, showed that between 1994 and 2005, there were 3,291 cases of active infection reported by the county's Tuberculosis Control Program and of those, about 8 percent were ill with M. bovis. Roughly the same pattern was observed in 2007.

The sale of raw milk cheeses in New Zealand is currently limited and subject to strict controls. See http://foodsafetywithjaybee.blogspot.com/2007/06/
free-choice-or-safety-of-population.html
Extra hard Italian Parmesan-style raw milk cheeses like Grana Padano, Pamigiano Reggiano, Romano, Asiago and Montasio have a low water activity of about 0.693, which prevents the growth of bacterial pathogens.

It had to happen!

In the USA, the argument about raw milk still rages. We now see the spectacle of lawyers claiming that consumers are being deprived of their rights to choose their food, while others sue the suppliers for selling dangerous milk.

The raw milk lobby claims that pasteurization robs the milk of its nutritional value and the natural enzymes that help the human digestive system. I am not aware of any scientific evidence to support this. They also vociferously claim that pasteurization kills the “good bacteria”. The zealous consumers claim that their rights are being trampled if they are prevented from buying the product. The regulators point to the dangers of consuming raw milk, such as the diseases caused by Salmonella, Campylobacter, Escherichia coli, Listeria and others, a point conveniently ignored by the raw milk proponents.

The hazards of consuming raw milk have been known for a long time. In Ontario around 1900, over 10% of all childhood tuberculosis was thought to be caused by unpasteurized milk. The rate of tuberculosis infection and many other milk-borne diseases in children fell dramatically after enactment of a law in 1938 requiring milk to be pasteurized; this was hailed as a major achievement.

The fact is that between 1998 and 2005, a total of 45 outbreaks resulting in more than 1,000 illnesses, 104 hospitalizations and two deaths due to raw milk or soft raw milk cheese were reported to the Centres for Disease Control and Prevention. There have been more recent, high-profile cases. Pathogens were found in 13 percent of bulk tank raw milk samples by a survey of Pennsylvania dairy farms in 2006. In California, 2008, new regulations set a limit of 10 coliforms per millilitre of raw milk. Raw milk suppliers maintain that the regulation will put them out of business, which suggests to me that they feel unable to meet this specification. But it's the same standard used for pasteurized milk. <For an explanation of the use of coliforms, see "Is hamburger a greater risk for E. coli" this blog, posted 3rd May 2008>.

Farmers who are selling raw milk are able to charge a significant premium for their product and understandably wish to continue supply. However, nothing comes without a price, and the right to sell a particular food product imposes certain responsibilities. Some American consumers have contracted serious disease from drinking raw milk. Unfortunately, children have no choice in the source of their milk and several have suffered haemolytic uremic syndrome (which has a 90% mortality rate without treament) and a number have required kidney transplants. The suppliers are now being sued.

In New Zealand, NZFSA has recently renewed its warning to consumers about raw milk cheeses, which have recently been approved for sale here. People with compromised immune systems, the elderly or pregnant women are urged to avoid these products.

Free Choice or Safety of the Population?

Governments and regulators are always in a difficult position. Do they allow total freedom of choice, or does their responsibility to the population require them to make restrictive decisions based on the greater good of the people? The government then performs a balancing act, running the risk of being labelled as Big Brother (or at least Nanny Government) or as being irresponsible. For example, should we all be allowed to use any chemical we can obtain to relieve the monotony of our daily lives, or should there be regulations to control the use of mind-altering substances and thus protect us from ourselves? If we allow unfettered use of any substance and thus maintain personal freedom, how do we protect the innocent - those who are too young or too poorly educated to know that these materials may be harmful?

Most people would probably come down on the side of some restrictions for the use of drugs, though some would argue for freedom of choice. The same applies to the sale and consumption of raw milk and raw milk products.

I have discussed raw milk before in this blog. I might have left it at that, but the New Zealand Government, in the form of the New Zealand Food Safety Authority has now called for submissions on a proposal to permit direct imports of Roquefort, a soft raw milk cheese made in France, and extra hard Parmesan-style raw milk cheeses Grana Padano, Pamigiano Reggiano, Romano, Asiago and Montasio. An extensive programme of risk assessment has already been undertaken and the Authority is now consulting with industry groups.

This development may lead some members of the community to believe that Big Brother has been wrong all along and is now backing down. Extra hard cheeses have a low water activity* of about 0.693 that prevents the growth of most bacteria. Soft cheeses, such as Brie, Camembert and Roquefort have much higher water activities and thus may permit the growth of pathogens such as Listeria monocytogenes (see post To Pasteurize or not? - 10th December 2006). The truth is that cheeses made from raw milk are not as safe as those made with pasteurized milk.

European Community (EC) legislation sets microbiological, food safety and process hygiene criteria that reduce the risks in consumption of raw milk cheeses. NZFSA has recommended that if these products are to be directly imported and ultimately manufactured in New Zealand, additional risk mitigation measures should be introduced:

• 100% verification of certificates attesting that the relevant EC standards have been met

• continuing monitoring of products to check for E. coli levels, which can indicate unsafe manufacturing conditions leading to faecal contamination of the cheese.

It is expected that leaflets, posters and point of sale brochures will be required to educate the consumers on the risks of eating cheeses made from unpasteurized milk and that labelling of the products will be mandatory. Yet another acronym has been added to our lexicon: YOPI - Young, Old, Pregnant or Immunocompromised. This group of the population should not consume raw milk products.

*Water activity is a measure of the ability of water to take part in biological and chemical reactions. It is measured as a ratio of the partial vapour pressure of the food to that of pure water. That sounds complicated, (it's not) but it results in a scale of water activity running from 0 to 1. Generally speaking, the lower the water activity, the harder it is for micro-organisms to grow. Water activity in foods can be controlled by salts and sugars. So we can formulate food to have a particular water activity and thus preserve the food.