To pasteurize or not to pasteurize? That is the question of the decade, as a growing number of people looking for more natural ways to boost their health consider adding raw milk to their diet.
Raw milk is milk from cows, sheep, or goats that has not been pasteurized, or treated with heat, to kill disease-causing bacteria.
Federal health officials consider raw milk to be “one of the riskiest foods” because it can contain harmful germs like campylobacter, E. coli, and salmonella that can have serious and potentially fatal consequences. Groups like the U.S. Food and Drug Administration and the American Academy of Pediatrics have warned against consuming it.
Yet, surveys show that an estimated 3.2 million people in the U.S. consume or serve raw milk in their homes each week. Raw milk producers say we’re in a “raw milk renaissance,” claiming that the liquid contains an ecosystem of probiotics and vitamins that can prevent asthma, treat diseases of the gut, and more.
Experts say that the proposed health benefits of raw milk don’t outweigh the documented risks—and likely don’t even exist. Still, as raw milk legalization expands in America and other countries, they predict it will become even more popular, igniting fiery debates among farmers and scientists.
Why do we pasteurize milk in the first place?
Raw milk and other unpasteurized dairy products like cheese, ice cream, and yogurt can host a variety of pathogens responsible for diseases such as salmonellosis, listeriosis, tuberculosis, typhoid fever, campylobacteriosis, and diphtheria.
These germs can come from cows’ poop or infected udders, as well as from unsanitary barns, milking equipment, and farmers’ hands.
Before 1950 when routine pasteurization became widespread in the U.S., milk-borne outbreaks were estimated to make up 25 percent of all disease outbreaks.
The most common pasteurization treatment in the U.S. uses metal plates and hot water to heat milk to 161 degrees Fahrenheit for at least 15 seconds to kill pathogens. Low levels of harmless bacteria that can spoil the milk persist even after pasteurization, so rapid cooling is critical to prevent their growth. This is why it’s important to keep milk refrigerated. (Other parts of the world use an ultra-high temperature process that keeps milk fresher for longer, which is why it does not need to be refrigerated.)
Prior to heating, milk samples must test negative for drugs (cows are sometimes treated with antibiotics for infections in their udders) and stay below limits for total bacterial loads that would indicate the presence of pathogens.
Still, pasteurization isn’t perfect, experts say.
“Pasteurization doesn’t eliminate risk, but it does reduce it considerably,” says Nicole Martin, a dairy microbiologist and director of the Milk Quality Improvement Program at Cornell University. “The data is very clear that those who consume raw milk are at a much higher risk of getting sick.”
What are the risks of consuming raw milk?
Common symptoms of the illnesses caused by these outbreaks include vomiting, diarrhea, fever, headache, abdominal pain, and body aches. Most healthy people will recover within two to five days, but some can develop chronic or life-threatening diseases, according to the U.S. Centers for Disease Control and Prevention. These include reactive arthritis, Guillain-Barré syndrome, which can cause paralysis, and hemolytic uremic syndrome, which can lead to kidney failure, stroke, and death.
Anyone can get sick from drinking contaminated raw milk, but adults aged 65 and older, people with weakened immune systems, pregnant people, and children younger than 5 face the greatest risks.
Children’s immune systems aren’t fully developed, so they’re more vulnerable to smaller doses of bacteria that may not hurt adults. Meanwhile, raw milk or milk products have also been associated with a fivefold increase in toxoplasmosis among pregnant people—a parasitic infection that can pass to babies during pregnancy—as well as listeriosis, which is associated with stillbirths, miscarriage, and other bad outcomes.
One study that analyzed reported outbreaks from 2009-14 found that unpasteurized dairy products were associated with 840 times more illnesses and 45 times more hospitalizations than pasteurized products.
State and local health departments aren’t required to report foodborne disease outbreaks to federal officials, so these numbers are “the very tip of the iceberg,” says John Lucey, director of the Center for Dairy Research at University of Wisconsin-Madison and professor of food science. “The vast majority of people who get sick don't go to their doctor, so the numbers we see are massively underreported.”
Farms that produce unpasteurized products do have food safety plans in place to prevent outbreaks. Some, such as Raw Farm in Fresno, California, use FDA-approved methods to test every batch of raw milk for four pathogens: campylobacter, E. coli, salmonella, and Listeria monocytogenes, says Mark McAfee, founder of Raw Farm and the Raw Milk Institute, an international nonprofit that promotes the safe production of raw milk products. Some farms also check coliform levels daily, which can indicate the potential presence of pathogens.
However, food safety experts warn that raw milk can still contain harmful bacteria even after frequent testing because small amounts can grow from the time it’s collected to the time a person drinks it. Even if farmers keep their animals, equipment, and barns clean, they cannot guarantee their raw milk and products are free of pathogens.
“Even the best, most rigid programs to ensure the safety of raw milk can’t eliminate the potential presence of pathogens like pasteurization can,” said Joe Reardon, senior director of food safety programs with the National Association of State Departments of Agriculture Foundation. “When you look at the millions of gallons of milk consumed every day in this country—in our schools, restaurants, homes—the track record speaks for itself.”
Are there benefits to drinking raw milk?
So why is raw milk so popular if it carries all these health risks?
McAfee said consumers are more interested in natural ways to improve their health, especially since the COVID-19 pandemic began, and are becoming more aware of the difference between what you might think of as raw milk versus raw milk that is produced and tested for human consumption.
“Dirty raw milk is not the raw milk that is emerging as a world-class high-value immune-system-building anti-inflammatory and delicious food,” McAfee said. “Raw milk that is produced by highly trained farmers using different standards and testing is made to feed people, not processors.”
Raw milk producers argue that raw milk, because it’s not pasteurized, retains more enzymes, vitamins, probiotics, and other beneficial nutrients that boost the immune system and gastrointestinal tract. They claim this can help prevent and lower rates of asthma, allergies, lactose intolerance, eczema, fever, and respiratory infections, as well as treat Crohn's disease, irritable bowel syndrome, and other gut issues.
But public health officials, dozens of studies, and the experts who spoke to National Geographic say there’s not enough scientific evidence to support those claims.
Many studies can’t prove that raw milk is directly responsible for any one health benefit. Most are based on questionnaires given to families living on farms—which are home to a whole host of other germs and allergens that researchers say might actually be the cause of any observed health benefits.
There also isn’t strong data that shows pasteurization makes milk less healthy.
Some evidence shows that the process moderately reduces concentrations of some vitamins and proteins by less than 10 percent, as well as some enzymes that experts say have no proven health benefits for people. Most vitamin levels are “fairly low to begin with,” Martin said, so “it’s not a major source for nutrition.” (Vitamins A and D are usually added to milk for this reason.)
Is raw milk legal?
Since 1987, the FDA has banned dairies from distributing raw milk packaged for human consumption across state lines. However, each state makes its own laws about selling raw milk within its borders.
The latest data show that 28 states allow the sale of raw milk with varying restrictions. Some, such as California, Connecticut, Arizona, and South Carolina, allow raw milk to be sold in retail stores; others only allow raw milk producers to sell their products directly to consumers, including Texas, New York, Minnesota, and Illinois.
Meanwhile, raw milk can be sold in some states like Colorado and Tennessee via “herd shares” — when a person buys an “ownership interest” in a cow or herd and is entitled to a portion of the raw milk it produces.
“On one side of the equation, states that legalize raw milk can regulate the system to ensure it’s safe,” Martin said. “On the other … states considering legalization might think they’re sending a message to consumers that it’s safe to drink.”
But even as the states debate the ethics of raw milk, the science remains clear: Studies have shown that the average number of outbreaks linked to raw milk each year increased fourfold from 1993-2006 to 2007-12 as more states legalized it—and that those states had 3.2 times more outbreaks than those where it’s illegal.
“There's no real controversy about raw milk in the academic community,” Lucey says. “When you think about the fact that raw milk can sicken people, including kids and pregnant women who could lose their babies, that’s where it gets real. The risks just aren’t worth it.”