What are the risks of raw milk? Experts warn of increased chances of infection, illness
Proponents claim raw milk is healthier than pasteurized dairy, but microbiologists say it's risky to consume
Despite the warnings of experts, there are growing conversations around the supposed benefits of raw milk.
Raw milk, also known as unpasteurized milk, is milk that has not undergone the pasteurization heating process that eliminates harmful microorganisms like bacteria and viruses.
Public figures — including Robert F. Kennedy Jr., U.S. president-elect Donald Trump's nomination for health secretary — are advocating that people consume raw milk. They argue that unpasteurized milk has health benefits compared to pasteurized milk.
Microbiologists, however, say the evidence clearly shows drinking unpasteurized milk is far riskier and may lead to harmful outcomes.
Last month, raw milk sold by a California farm was recalled after avian flu virus was found in multiple samples.
The product's distribution has been suspended, and health officials say no known cases of bird flu virus have been confirmed in people who drank the raw milk.
"Data really shows that people should not be consuming raw milk," Lawrence Goodridge, a food safety professor at the University of Guelph, told The Dose's Dr. Brian Goldman.
What is pasteurization?
Pasteurization, developed by French chemist Louis Pasteur in the mid-1860s, is a process by which liquids are heated to eliminate harmful pathogens, including bacteria and viruses, while retaining the liquid's nutritional quality.
In Pasteur's case, the chemist was attempting to pasteurize wine by heating it between 60 C and 100 C.
For milk to be pasteurized, it must be heated to 63 C for 30 minutes, or 72 C for 15 seconds.
Toronto was the first city in Canada to mandate pasteurization in 1914.
Pasteurization was made mandatory by Health Canada in 1991, and it is illegal to distribute or sell raw milk in Canada. Canada is the only G7 nation that bans the purchase and sale of raw milk.
Butter and cheese made from unpasteurized milk is allowed to be sold, so long as the products have been aged a minimum of 60 days.
What are the risks of consuming raw milk?
Consuming raw milk raises the risk of coming into contact with harmful bacteria — like E. coli, Listeria, salmonella and campylobacter — as well as viruses like H5N1, better known as bird flu, says McGill associate professor Jennifer Ronholm.
One of the most virulent forms of E. coli is transmitted through raw milk and can cause hemolytic uremic syndrome, a condition which affects the kidneys and the body's ability to clot blood.
In 2023, an E. coli outbreak in B.C. linked to the consumption of cheese made from raw milk led to 10 people getting sick and one person dying.
"Much of the pathogens that are in the raw milk, particularly E. coli, are coming from the cattle feces," said Ronholm, who holds a Canada Research Chair in agricultural microbiology.
"No matter how clean you are when you're cleaning the cows off to milk them, you're not going to avoid microscopic pieces of feces."
Cows that have contracted infectious diseases can also transmit viruses like hepatitis A, norovirus and tick-borne encephalitis virus through their milk, according to Goodridge, who is director of the Canadian Research Institute for Food Safety.
According to a 2023 commentary published by the Public Health Agency of Canada, Canada saw 263 confirmed cases of intestinal and zoonotic illnesses transmitted through raw milk consumption between 2005 and 2013, and seven outbreaks between 1998 and 2021.
That figure is likely an underestimate, according to the authors, since "the vast majority of enteric illnesses often do not present to health-care or are tested to a confirmatory extent."
A 2017 U.S. study used publicly available data to estimate that raw dairy products cause 840 times more illnesses and 45 times more hospitalizations than pasteurized dairy products.
Misconceptions about raw milk
The U.S. Food and Drug Administration refutes claims that raw milk cures lactose intolerance, asthma and other allergies; prevents osteoporosis better than pasteurized milk; and enhances the human immune system.
Raw milk proponents also claim that pasteurization eliminates or reduces nutrients and minerals, ridding milk of its dietary benefits.
According to a 2011 systematic review and meta-analysis examining the effects of pasteurization on milk vitamins, researchers saw a decrease in vitamins B12 and E following pasteurization, while vitamin A levels increased.
However, the studies cited in the meta-analysis showed a range of changes to the vitamins, with some studies showing no change in concentrations, while others showed changes ranging from low single-digit percentages to around 35 per cent depending on how hot the milk was heated.
One study cited in the meta-analysis, published in 1994, showed no change in vitamin B12 concentration when milk was pasteurized.
"The vitamin content of milk is actually much more affected by factors about the cow, such as her age, stage of her lactation cycle, and her diet … than by pasteurization," wrote Ronholm in an email.
"This means that if your raw milk is coming from a single cow or a small group of cows, the nutritional value can be highly variable based on that individual cow's nutrition and health status — which changes over time"
Ronholm argues that buying pasteurized milk in Canada is better than raw milk because vitamin D is added to help with calcium absorption.
Additionally, she says pasteurized milk from a grocery story contains milk supplied from hundreds of cows, meaning "the milk will be a much more nutritionally consistent product."
Goodridge says he disagrees with the argument that raw milk is safer to consume simply based on anecdotal evidence from people who have not experienced harmful consequences.
When it comes to consuming unpasteurized milk, Goodridge compares it to other risky behaviours like speeding.
Speeding won't always lead to collisions, "but the risk of getting into an accident certainly increases if one speeds," he said.
Likewise, consuming raw milk doesn't guarantee that someone will contract an E. coli infection, but the risk of infection increases — especially for young children, older people, people with compromised immune systems and pregnant people.
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