According to a part of his online promoters, unpasteurized or “raw” milk can “heal the gut,” boost the immune system, ward off allergies, give you healthier skin, and even help with muscle building. Perhaps more common is the idea that pasteurization – the heating process used to kill harmful bacteria in milk – reduces the amount of vitamins and “good” bacteria in the drink, so raw milk is supposed to be better for you. Recent media reports suggest that this perception is creating a growing demand for raw milk that some farmers are happily responding to.
So what does the scientific evidence say? There is some evidence that pasteurization may have a slight effect on the nutritional content of milk. But drinking raw milk carries the risk of contracting serious and life-threatening infections.
Pasteurization, named after the scientist Louis Pasteur (1822-1895), involves heating certain types of food and beverages at around 72°C for at least 15 seconds, then quickly cool them to 3°C. This process reduces the number of potentially harmful bacteria (pathogens) and other microorganisms which reduce the shelf life of the product.
A 2011 meta-analysis compared the results of 40 studies study the effects of pasteurization on vitamin levels in milk. He showed that pasteurization reduced the amount of vitamins B1, B2, C and folate in milk. But the authors also concluded that, aside from vitamin B2, levels of these vitamins were so low to begin with that milk was not an important dietary source of them.
They also found that some of the published scientific evidence suggested that raw milk may offer some protection against allergies. However, the many environmental factors involved in agriculture made it difficult to draw clear conclusions.
Another 2015 study looked at how often 983 babies under 12 months had fever and respiratory tract infections such as colds (recorded by their parents). He compared those given raw milk and those given UHT (ultra-high temperature processed) milk, which is heated to a much higher temperature (135°C) than in regular pasteurization.
The authors concluded that the consumption of raw milk during the first year of life could reduce the risk of fevers and respiratory infections by approximately 30% compared to UHT milk. They said if a method could be found to remove pathogens from milk with only minimal treatment, it could have a huge impact on babies’ health, given how common these infections are.
But it’s important to point out that this is not the same as saying that raw milk has protective powers for anyone who drinks it. It should also be noted that babies under 12 months are generally recommended breast milk or formula because they cannot get all the nutrients they need from cow’s milk. Perhaps more importantly, these young infants are at particular risk from pathogens found in raw milk, which can threaten even healthy adults.
Harmful bacteria
The average human body contains approximately 39 trillion individual bacterial cells – more than the total number of human cells in the body. We need a mix of microorganisms, perhaps commonly referred to as “good” bacteria, to fight off the bad ones.
Given that microorganisms are found everywhere, from Antarctica to the bottom of the sea, it is perhaps unsurprising that they are commonplace on the average dairy farm. Some harmful bacteria that have been linked to drinking raw milk include Mycobacterium bovis (the causative agent of bovine tuberculosis), Campylobacter, Salmonella, Listeria and toxin producers E.coli.
Research has shown that drinking raw milk can lead to infections with these pathogens. In Colorado, USA, in 2015, 12 people were infected with a drug-resistant strain of Campylobacter jejuni after drinking raw milk. Although no one died, one person was hospitalized and all had symptoms ranging from bloody diarrhea to stomach cramps and headaches. In the same way, in Wales in 2017, 18 cases of Campylobacter infection have been reported in people who drank raw milk.
Due to the dangers associated with raw milk, its sale is often strictly regulated. For example, in most of the UK it can only be sold by registered producers that use approved production methods. Farms must be inspected twice a year, and milk must be labeled with a health warning and tested four times a year for the presence of pathogens. But in Scotland, selling raw milk for drinking is completely prohibitedas is the case in Canada and Australia.
The evidence for the benefits of consuming raw milk is mixed, but the research generally suggests that the potential contamination of raw milk with harmful bacteria is too great a risk compared to the perceived health benefits.
