SAN FRANCISCO (KCBS RADIO) – You might have heard raw milk touted as a healthy alternative to pasteurized milk, but a new study from researchers at Stanford University indicates that it could contribute to flu outbreaks. Here’s what you need to know.
According to the study published this week in the Environmental Science & Technology Letters journal, flu virus remained detectable for days in raw, unpasteurized milk. Specifically, the research focused on the persistence of influenza A virus H1N1 PR8 (IAV PR8).
“These findings highlight the potential risk of zoonotic virus transmission through raw milk consumption and underscore the importance of milk pasteurization,” said the study authors. “The prolonged persistence of viral RNA in both raw and pasteurized milk has implications for food safety assessments and environmental monitoring, particularly in the context of the environmental surveillance of influenza viruses.”
A press release from Stanford published by the American Association for the Advancement of Science’s Eurekalert said that the study showed that flu virus can remain infectious in raw milk for up to five days. It also noted that more than 14 million Americans consume raw milk annually.
Per the U.S. Centers for Disease Control and Prevention, raw milk is simply “milk that has not been pasteurized, a process that removes disease-causing germs by heating milk to a high enough temperature for a certain length of time.” This process does not impact the nutritional benefits of milk and it has significantly reduced milk-borne illness since the 1900s, the CDC added.
Stanford’s press release said that “proponents of raw milk claim that it leaves more beneficial nutrients, enzymes, and probiotics than in pasteurized milk, and can boost immune and gastrointestinal health.” However, the U.S. Food and Drug administration released a notice this spring about raw milk misconceptions that disputed these claims.
“None of the claims made by the raw milk advocates that we have examined for you can withstand scientific scrutiny,” said the FDA. In fact, the FDA has tied raw milk to over 200 illness outbreaks.
Alexandria Boehm, senior author of the Stanford study and the Richard and Rhoda Goldman Professor of Environmental Studies in the Stanford Doerr School of Sustainability and the Stanford School of Engineering, said the new research “highlights the potential risk of avian influenza transmission through consumption of raw milk,” and at a time when outbreaks of avian flu have caused pandemic concerns. Just this month, public health officials in California said that two possible cases of H5 bird flu in cats that ingested recalled raw milk in Los Angeles County were under investigation.
“It’s really a dangerous practice,” said Dr. Michael Osterholm, University of Minnesota director of the Center for Infectious Disease Research and Policy said this summer of raw milk drinking. “I’ve worked up far too many outbreaks of people severely ill from consuming raw milk and getting infected with any number of bacteria and viruses. So today we’d be concerned about people drinking this milk relative to the potential to become infected with this flu virus.”
The Stanford research team also found that flu virus RNA remained detectable in raw milk for 57 days. It was also detectable, but not as much, in pasteurized milk. RNA carries genetic information but isn’t considered health a risk.
Alessandro Zulli, a postdoctoral scholar in civil and environmental engineering and study co-lead author, said the prolonged presence of RNA has implications for food safety assessments and environmental surveillance that rely on RNA.
Bird flu, or influenzas A, has not proven as dangerous to people yet but it could mutate to become dangerous. Flu viruses overall already infect more than 40 million people in the U.S. every and kill more than 50,000.
While the new study highlights another potential risk to others known to be associated with raw milk, an Annenberg Public Policy Center survey from this summer found that not even half of U.S. adults realized drinking raw milk is not as safe as drinking pasteurized milk. It also found that nearly a quarter (24%) of Americans either think incorrectly that pasteurization is not effective at killing bacteria and viruses in milk products or are not sure if it does.
Last year, a study published in the Journal of Food Protection revealed that 4.4% of U.S. adults had reported consuming raw milk at least once in the past year, based on data from the 2016 Food Safety Survey and the 2019 Food Safety and Nutrition Survey conducted by the U.S. Food and Drug Administration. That study also found that 1.6% of U.S. adults reported consumption of raw milk once per month or more often and 1% reported consumption once per week or more often.
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“The individuals who consumed raw milk in the previous 12 months were more likely to be younger, living in a rural area, and living in a state in which retail sale of raw milk is legal,” said the 2023 study.
One of the proponents of raw milk’s benefits is Robert F. Kennedy, Jr. This October, Kennedy railed against the suppression of raw milk (as well as psychedelics, peptides, stem cells, and more) in an X post after President-elect Donald Trump announced that he had tapped the former environmental lawyer to lead the Department of Health and Human Services in his incoming administration.
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