Risks related to foods generally come from the presence and concentration of certain pathogenic bacteria. These bacteria are always present in foods like raw and pasteurized milk, dairy products, fish, meat, packaged fresh foods, fruits and vegetables, but usually in very low concentrations. They are responsible for almost all food-borne infectious diseases.
As for illnesses that used to be linked to some foods (including raw milk), like tuberculosis and brucellosis, they have been practically defeated in Europe and North America, though can still be a problem in other countries or in a few poorer regions. This is why it is important to consider the risks involved in eating foods like milk, meat, eggs and raw fish in higher-risk countries.
In any case, if we take the total number of cases of bacterial food poisoning and illnesses, those attributed to raw milk represent a tiny percentage.
The main pathogenic bacteria that concern raw milk are:
- Campylobacter jejuni
- Escherichia coli (E. coli O157:H7)
- Listeria monocytogenes
- Salmonella spp.
Salmonella is responsible for the majority of food poisoning. In most cases it causes gastrointestinal problems associated with fever and weakness, which pass naturally after a couple of days. These bacteria live in animal cells and high-protein foods, especially when kept at warm temperatures, and also in contaminated water. In the case of raw milk, the risk increases if the milk is kept in contact with potential infected sources or not refrigerated properly. The Center for Disease Control (CDC) in the United States has recorded three cases of salmonella attributed to raw milk out of over a million total cases between 1999 and 2010.
Campylobacter jejuni is the second-most common bacteria responsible for food poisoning. In raw milk, Campylobacter jejuni is found mostly during the first hours after milking, after which the milk's antibodies trigger a defense mechanism that kills it. Therefore the risks decrease as the hours pass, as long as the milk is kept refrigerated and exposed to the air, and they increase with poor hygiene and contact with contaminated water. The symptoms for someone who eats a food with a high concentration of Campylobacter jejuni are dysentery and other gastrointestinal problems. They usually last a few days and go away on their own. Again looking at the United States, the CDC has calculated an average of 845,024 cases per year (from 1999 to 2010) of people affected by dysentery after eating a food contaminated with Campylobacter. Only 34 of these had drunk contaminated raw milk.
Escherichia coli O157:H7 is naturally found in the human intestine and in the intestines of other warm-blooded animals. People who drink raw milk are at risk if the milk has come into contact with fecal material from animals or people who carry the bacteria. The direct impact of Escherichia coli O157:H7 on humans is minimal, but it can cause potentially serious and even fatal illnesses like hemolytic-uremic syndrome. The CDC estimates that between 1999 and 2010 only five out of 63,153 annual cases of disease caused by E. coli were due to drinking milk.
Finally we come to the most feared, Listeria. It is important to know that only some subclasses of this bacteria can cause Listeriosis, which can be fatal only if the bacteria are ingested in large quantities and only in particularly at-risk cases, like newborns, pregnant women, the elderly and people with compromized immune systems. In the majority of cases it causes gastroenteritis.
Listeria is a very versatile bacteria, and can reproduce inside animal cells and in decomposing plant cells. The most common sources of this bacteria are badly stored silage, fetal material from infected animals and dirty equipment used to process meat. Listeria flourishes in cool, damp environments and can be found in variable quantities practically everywhere, in our houses and our bodies. We ingest small quantities of Listeria every day with no effect, and the same happens when we drink raw milk. There have been very few cases of listeria contamination involving milk and raw-milk cheeses, especially if the cheese is aged for a long time. In the past 12 years, again in the United States, there has not been a single case. The foods most commonly containing infective strains of Listeria are generally prepared foods, especially meat-based.
Let's move on to pasteurized milk, which is not without its possible risks and side-effects.
Leaving aside the enormous harm caused to the water and air by intensive farming for the production of milk for the mass market (and for pasteurization), the industrial process has triggered a mechanism from which it is hard to escape.
It is common knowledge that farms for the intensive production of milk use a massive quantity of antibiotics, to avoid the cows getting sick and being unable to produce. Antibiotics are designed to kill harmful bacteria, but they also kill useful ones. This is true for both humans and animals and what they produce (meat, milk, etc.).
Additionally, as the old saying goes, "what doesn't kill you makes you stronger," sometimes some microbes survive the antibiotic extermination and end up in the milk. Finding themselves in a competition-free environment, they begin to proliferate and to perpetuate the antibiotic-resistant strain. They end up in what we touch and eat, making us more and more sick. The vicious circle continues, and we are told that we need more measures, more safety... for example, that we have to pasteurize the milk.
What need is there for antibiotics if the cow is allowed to move freely and is healthy, if the environment is hygienic, if the product is genuine? What need is there for pasteurization if milk is controlled as it is today, clean but still alive, rich in beneficial bacteria? Pasteurization is supposed to mean sweeping the slate clean, cancelling any trace of any wrongdoing. Luckily or unluckily, that's not exactly how it works.
One of the reasons we need more and more antibiotics is that our immune defenses have been reduced to a historic low. We don't drink raw milk because we're worried about getting sick, and in doing so we relinquish all the probiotic bacteria that could useful for the body's defenses.
The process of pasteurization kills the majority of pathogenic bacteria mentioned above, but not only. In addition, in fact, it also kills many of the beneficial lactic bacteria which are the natural enemies of the pathogens. In short, pasteurization kills the milk's natural bactericidal capacity. This means the remaining bacteria can multiply unimpeded.
Additionally, industrial milk used for pasteurization and large-scale distribution often contains hormones adminstered to the cows to make them produce more milk. These hormones have harmful effects on growth and health, endangering the hormonal balance and causing everything from acne to breast and prostate cancer.
Weighing up everything, where is the harm and where is the benefit?
Read the article by Mark McAfee, Organic Pastures Dairy CEO, on the 15 things that pasteurization kills.
Read the paper by Prof. Dr Ton Baars on the International Raw Milk Conference.
Read the article by Dr. Ted Beals on pathogens in food and food poisoning stats.
Read the article written by Dr. Claudia Costanza n the damages caused by pasteurization.
Read this study by Dr. Kenneth Todar on the problems caused by antibiotics and on antibiotic-resistent bacteria.
Read this study by Dr. Ricki Lewis on the increasing number of antibiotic-resistent bacteria and on the use of antibiotics in dairy farms.