“Chance only favors the mind which is prepared.”
- Louis Pasteur, French chemist, microbiologist, and immunologist
“The growing availability of raw milk is a loss for public health.”
- Marion Nestle, American molecular biologist, nutritionist, and public health advocate
There is no scientific evidence that raw milk is healthier for you than pasteurized milk, but there is an abundance of evidence that raw milk is potentially very dangerous. By definition raw milk is synonymous with unpasteurized milk. (The raw milk designation also applies to other dairy products like ice creams, yogurts, and cheeses.) On July 1, 2023, Iowa became the 29th state to allow the sale of raw milk. For anyone familiar with the extraordinary health benefits of pasteurization, legislation like this represents a dangerous step backward. In this Germ Gems post, I explain why pasteurization is so crucial and provide historical notes on its namesake, Louis Pasteur.
What is pasteurization and what are the pros? In December 2022, the scientific world celebrated the 200th birthday of Louis Pasteur. Pasteur was an accomplished chemist and made important discoveries in the field of chemistry. But to the general public, he is best known for his invention of the process now called pasteurization—the technique of treating milk and wine to stop bacterial contamination. In 1865 when Pasteur patented his method to treat the diseases of wine (that soon was applied to beer and milk), the Germ Theory of Disease in humans was in its infancy.
Raw milk (from cows, sheep, or goats) along with other raw dairy products like unpasteurized ice creams, yogurts, and cheeses can harbor bacteria that cause common food-borne illnesses—such as salmonella, listeria, campylobacter, and E. coli. Pasteurization kills bacteria that are responsible for spoilage and disease. To pasteurize milk and dairy products means heating them at 145F (63C) for a minimum of 30 minutes.
When milk pasteurization began in the early 1900s, millions of diarrheal illnesses and deaths in children declined dramatically. Since then, the lifting of laws requiring pasteurization has been linked to dramatic increases in food-borne illnesses. Between 1998 and 2018, the Center for Disease Control and Prevention (CDC) reported that outbreaks during those years sickened 2,645 people and caused 228 hospitalizations and three deaths. States that had legalized the sale of raw milk at retail stores had three times as many outbreaks as states that prohibited such sales.
The people at greatest risk of severe illness from raw milk are adults 65 years and older, children under 5 years, and those with a weakened immune system (including pregnant women who are at risk of passing Listeria on to their unborn fetus). The CDC’s website on raw milk highlights “Fast Facts: Why Raw Milk is Unsafe?” According to the CDC, while use of good hygiene practices on farms can reduce the chance of milk getting contaminated, it does not eliminate the risk.
The impact on children is particularly troublesome because the decision to provide them with raw milk is made by others. In the article “Here’s Why Raw Milk Is Risky for Kids,” in July 18, 2023 MedPage Today, medical journalist, Kristina Fiore tells the story of the 7 year old son of Mary McGongle-Martin. McGongle-Martin thought that having her son drink raw milk would be more healthful than drinking pasteurized milk. But after drinking raw milk, her son developed a life-threatening infection caused by Shiga-toxin producing E. coli. After several months in the hospital, including treatment in the intensive care unit, where he was transfused, put on a respirator, and dialyzed for kidney failure, he was discharged home. McGongle-Martin says, “I almost killed my son” by giving him raw milk. She is now a board member of Stop Foodborne Illness (STOP), a national, non-profit public health organization dedicated to the prevention of illness and death from foodborne pathogens. (STOP was founded in 1993 by those impacted by a deadly strain of E. coli.)
Pasteurization: what are the cons? Raw milk advocates claim that pasteurization destroys the nutrients in raw milk that can fight off pathogens. Some advocates believe pasteurization destroys some of the vitamins found in raw milk. There is no scientific evidence that supports such claims and/or beliefs. To reiterate what I stated at the outset of this post, the fact is there is no scientific evidence that raw milk is healthier for you than pasteurized milk, but there is an abundance of evidence that raw milk is potentially very dangerous.
What is Pasteur’s legacy? Pasteur was the consummate practitioner of translational research bringing many of his discoveries “from the bench to the bedside.” These are, for example, the Germ Theory of Disease (stopping development of bacterial infections in humans and animals), vaccination (he was the first to vaccinate against rabies), and fermentation(he discovered the key role of microorganisms in creating beer, wine, bread, yogurt, and other foods). The French people recognized Pasteur as a hero while he was alive.
Given the recent bicentennial of Louis Pasteur’s birth, it is not surprising that an abundance of articles were published at the end of this past year on the subject of his legacy. (See, for example, “Innovation for infection prevention and control—revisiting Pasteur’s vision,” The Lancet, December 17, 2022; “Louis Pasteur’s devotion to truth transformed what we know about health and disease,” Science News, November 18, 2022; “Pasteurization: Pasteur’s greatest contribution to health,” The Lancet/Microbe, December 16, 2022.) In a December 17, 2022 editorial in Lancet, “Pasteur’s legacy in 21stcentury medicine,” the author posits, “Now, more than ever, the medical research community needs to hone creative and authentic science communication and public engagement skills to rebuild trust with a divided society so their work can save lives.”
I think we’d all agree that restoring the general public’s trust in science is at present Job Number One for public health organizations in America. In short, what we could really use right now is an American equivalent of Louis Pasteur.