A glass of raw milk may seem like a return to nature, but it could contain a cocktail of dangerous pathogens.
Imagine a time when a simple glass of milk could lead to a life-threatening illness. This was the reality before the widespread adoption of pasteurization in the early 20th century, a simple heating process that became one of public health's greatest triumphs 1 . Yet, a century later, this conquered threat is making a comeback.
Driven by claims of superior nutrition and "natural" benefits, unpasteurized or "raw" milk is experiencing a resurgence. This trend persists despite clear warnings from health organizations about the significant risks lurking in every sip. This article separates the science from the speculation in the raw milk debate, exploring the very real dangers and the enduring power of a simple public health intervention.
Milk was a documented carrier of severe diseases. Between 1912 and 1937, an estimated 65,000 people in England and Wales died from tuberculosis caught from bovine sources, primarily via milk 4 .
Pasteurization was implemented, dramatically reducing milk-borne illness. Before World War II, milkborne outbreaks accounted for 25% of all disease outbreaks from food and water in the U.S.
Thanks to pasteurization, milkborne outbreaks account for less than 1% of all disease outbreaks from food and water in the U.S. 4 .
Despite its "natural" appeal, raw milk can harbour a veritable zoo of pathogenic microbes. The udder, even in a healthy animal, is not a sterile environment. Contamination can occur through multiple routes: direct transmission from the cow's blood, a udder infection (mastitis), contact with feces during milking, or from dirty equipment 1 4 .
Some strains can produce toxins leading to hemolytic uremic syndrome (HUS), a severe condition that can cause kidney failure 7 .
A bacterium that causes bovine tuberculosis, which can be transmitted to humans 1 .
For the first time, H5N1 was detected in dairy cows in 2024 and has been found in raw milk. While it remains unknown if humans can contract it from drinking raw milk, studies show that mice can get sick from consuming infected, unpasteurized milk. Pasteurization, however, has been shown to kill the virus 1 .
Proponents of raw milk often claim it has health benefits that are destroyed by pasteurization. However, scientific evidence does not support these claims 4 .
| Claim | Scientific Rebuttal |
|---|---|
| Retains more nutrients and beneficial enzymes | Pasteurization causes only minor, insignificant reductions in a few vitamins. Key nutrients like protein, calcium, and most vitamins remain unaffected 1 4 . |
| Contains natural probiotics for gut health | The bacteria in raw milk are not the proven probiotic strains found in yogurt. More importantly, they are outnumbered by potential pathogens from environmental sources 1 9 . |
| Can cure or reduce lactose intolerance | There is no lactase enzyme in raw milk to break down lactose. Lactose-intolerant individuals will react to both raw and pasteurized milk 1 9 . |
| Reduces risk of allergies and asthma in children | Some observational studies found an association, but these are not conclusive. The authors of one key study explicitly warned against raw milk consumption due to serious health risks 1 9 . |
The perceived benefits of raw milk are not supported by robust scientific evidence, while the risks are well-documented and significant.
To understand the true public health impact, researchers conducted a comprehensive risk assessment, analyzing outbreak data in the U.S. from 2009 to 2014 . Their goal was to compare the disease burden between pasteurized and unpasteurized dairy products.
The study used data from the National Outbreak Reporting System (NORS), focusing on illnesses linked to Campylobacter, Salmonella, E. coli, and Listeria in cow's milk and cheese. The researchers calculated illness rates, accounting for factors like underreporting and population consumption data.
of all illnesses attributed to contaminated dairy were caused by unpasteurized products
of the population consumes unpasteurized dairy products
| Dairy Product Type | Incidence Rate Ratio (IRR) for Illness | Incidence Rate Ratio (IRR) for Hospitalization |
|---|---|---|
| Unpasteurized (vs. Pasteurized) | 840 times higher | 45 times higher |
This data translates to an average of 760 illnesses and 22 hospitalizations each year from outbreaks linked to unpasteurized dairy . The study also warned that as consumption of raw milk grows, outbreak-related illnesses are expected to increase steadily. A doubling in consumption could lead to a 96% increase in related illnesses .
This research provides a clear, quantitative foundation for public health warnings, demonstrating that the choice to consume raw milk carries a significantly elevated risk.
Producing safer raw milk requires rigorous testing. Farmers and scientists rely on specific tools and methods to monitor microbial quality. The Raw Milk Institute, an organization that trains farmers in risk management, recommends at least monthly testing for key hygiene indicators 7 8 .
| Tool or Reagent | Function in Testing |
|---|---|
| Testing Discs (Petri-Films/Peel-Plates) | Small, self-contained plates with a nutrient medium. The milk sample is applied to them to grow bacteria. 8 |
| Incubator | A device that maintains a constant, warm temperature (90°F / 32°C) optimal for bacterial growth over 24-48 hours. 8 |
| Sterile Pipettes | Used to measure and transfer precise, small volumes of the milk sample onto the testing discs without contamination. 8 |
| Sterile Water | Used to create dilutions of the milk sample to ensure bacterial colonies are countable. 8 |
| Test Type | What It Measures | Safety Benchmark (Rolling 3-mo. Average) |
|---|---|---|
| Standard Plate Count (SPC) | Total aerobic bacteria; a general indicator of hygiene and spoilage. | < 5,000 cfu/mL (colony-forming units per milliliter) 7 |
| Coliform Count | Bacteria commonly associated with fecal contamination and the environment. | < 10 cfu/mL 7 |
It is crucial to understand that these tests do not directly detect pathogens. Instead, they serve as general proxies for the overall cleanliness of the production process. Even milk meeting these standards is not guaranteed to be pathogen-free, which is why pasteurization remains the critical, non-negotiable step for public safety 7 .
The evidence is clear and consistent. The perceived benefits of raw milk are largely mythological, while the risks of severe foodborne illness are well-documented and significant 1 4 5 . Vulnerable populations—including children, the elderly, pregnant women, and the immunocompromised—are at the highest risk 1 5 .
Pasteurization is not a heavy, industrial process that destroys milk's goodness. It is a targeted, effective public health measure that eliminates pathogens with minimal impact on nutritional value 4 . In the debate between raw and pasteurized milk, science firmly sides with safety. Choosing pasteurized milk allows you to enjoy all the nutritional benefits of this staple food, without playing Russian roulette with your health.