Published in Emerging Infectious Diseases (a CDC journal) in 2017, researchers analyzed surveillance data on dairy-related disease outbreaks reported in the United States between 2007 and 2012.

Of the 81 outbreaks linked to dairy products during this period, 78 (96%) were caused by unpasteurized milk or cheese made from unpasteurized milk. These outbreaks produced 979 documented illnesses and 73 hospitalizations. At the time, less than 3.5% of the U.S. population consumed unpasteurized dairy products, meaning this small group accounted for nearly all dairy-related disease.

The most common pathogens were Campylobacter (responsible for the majority of outbreaks), Shiga toxin-producing E. coli, and Salmonella. The report noted that children under 5 were disproportionately affected and faced the highest risk of severe complications, including hemolytic uremic syndrome (kidney failure caused by certain E. coli strains). The CDC concluded that any claimed nutritional benefits of raw milk do not outweigh the documented infectious disease risk.

Published in Foodborne Pathogens and Disease in 2014, researchers conducted a systematic review comparing the per-serving risk of foodborne illness from raw versus pasteurized milk using outbreak and consumption data from the United States, Canada, and Europe spanning 1993 to 2012.

The calculated risk per serving was approximately 150 times higher for raw milk than for pasteurized milk. This ratio accounted for the much smaller volume of raw milk consumed relative to pasteurized milk. The pathogens most commonly responsible were Campylobacter jejuni, Salmonella species, and E. coli O157:H7.

The review noted that while individual outbreaks are often small (affecting a farm''s direct customers), the per-serving risk is substantial. Children, pregnant women, elderly people, and immunocompromised individuals face disproportionately severe outcomes from the same infections that might cause only mild diarrhea in healthy adults. The researchers concluded that from an infectious disease standpoint, raw milk is one of the highest-risk food products available to consumers.

Published by the U.S. Food and Drug Administration in 2020 as part of their ongoing food safety research, FDA scientists collected paired raw and pasteurized milk samples from the same dairy operations and performed detailed nutritional analyses.

Total protein content was statistically identical between raw and pasteurized milk (approximately 3.3 grams per 100 milliliters in both). Calcium levels showed no significant difference (approximately 120 milligrams per 100 mL). Potassium, phosphorus, riboflavin (vitamin B2), and total fat content were also unchanged by pasteurization.

The vitamins that did show measurable reductions after pasteurization were vitamin C (reduced by 10-20%) and some B vitamins (reduced by 5-10%). However, milk is not a meaningful dietary source of vitamin C for most people - a single orange provides more vitamin C than 10 glasses of raw milk. The FDA concluded that the core nutritional value of milk - protein, calcium, fat, and most vitamins - is preserved through pasteurization, and the small losses in heat-sensitive vitamins are nutritionally insignificant in the context of a normal diet.

Published in the International Journal of Environmental Research and Public Health in 2019, this systematic review examined whether the allergy-protective effects attributed to raw milk in European studies were confounded by other aspects of the farming environment.

The review analyzed 23 studies and found that farm children are simultaneously exposed to animal dander, stable dust, endotoxins (bacterial cell wall fragments), diverse microbes from soil and animals, and higher levels of physical activity outdoors. Each of these exposures has been independently associated with reduced allergy risk in separate research.

While several studies found associations between farm milk and lower allergy rates after adjusting for farming status, the reviewers noted that residual confounding is nearly impossible to eliminate in observational studies. Children who drink raw milk from their family farm also tend to spend more time in barns, have earlier and more frequent animal contact, and consume other unprocessed farm foods. The review concluded that the evidence is insufficient to recommend raw milk as an allergy-prevention strategy, since it is unclear whether the milk itself or the broader farming lifestyle provides the protection.

Published in the Annals of Family Medicine in 2015, researchers conducted a meta-analysis of 13 studies that tested lactose digestion in participants with confirmed lactose intolerance, comparing outcomes between raw and heated or pasteurized milk.

Using hydrogen breath tests (the clinical standard for measuring lactose malabsorption), the meta-analysis found no statistically significant difference in lactose digestion between raw and pasteurized milk. Both produced similar levels of hydrogen gas, indicating similar degrees of undigested lactose reaching the colon.

The researchers noted that while raw milk does contain some bacterial beta-galactosidase (an enzyme that breaks down lactose), the amount is far too small to meaningfully affect digestion. The concentration of lactase-producing bacteria in raw milk is roughly 1,000 times lower than what is present in yogurt or kefir, which do provide measurable digestive benefit. Self-reported tolerance improvements in surveys likely reflect placebo effects or the smaller serving sizes typically consumed when people switch to premium-priced raw milk.

According to CDC surveillance data compiled through the Foodborne Disease Outbreak Surveillance System (FDOSS), between 1998 and 2018, 202 disease outbreaks in the United States were traced to unpasteurized milk or products made from it. These outbreaks caused 2,645 documented illnesses, 228 hospitalizations, and 3 deaths.

Children under 5 years old accounted for 38% of all hospitalizations, despite representing only a small fraction of raw milk consumers. This disproportionate impact on young children occurs because their immune systems are still developing and they are more vulnerable to severe complications from Campylobacter, Salmonella, and E. coli O157:H7 infections - including hemolytic uremic syndrome, which can cause permanent kidney damage.

The CDC notes that these numbers likely undercount the true burden, since most foodborne illnesses go unreported and many small outbreaks on individual farms are never detected by surveillance systems. States that legalized raw milk sales saw significantly higher outbreak rates than states where it remained illegal, providing a natural experiment showing that increased access leads to increased disease.

Published in Pediatrics in 2014 (reaffirmed 2015), the American Academy of Pediatrics (AAP) issued a policy statement on the consumption of raw milk, based on a comprehensive review of available evidence on both the risks and purported benefits.

The AAP concluded that there are no demonstrated health benefits of consuming raw milk that cannot be obtained from pasteurized milk. The organization noted that while some observational studies have found associations between farm milk consumption and reduced allergies, these studies cannot separate the effect of raw milk from dozens of other farm-related exposures. No randomized controlled trial has demonstrated that raw milk provides health benefits superior to pasteurized milk.

The AAP specifically recommended against giving raw milk to infants, children, pregnant women, elderly people, and anyone with a compromised immune system. They noted that children under 5 face the most severe consequences from raw-milk-associated infections, including kidney failure and death. The statement emphasized that pasteurization is one of the most effective public health interventions in food safety history, having nearly eliminated milk-borne diseases that once killed thousands annually.

Published in the Journal of Food Protection in 2011, researchers collected and tested 2,034 raw milk samples from farms, retail stores, and direct-to-consumer sales across multiple U.S. states. Each sample was tested for the presence of major foodborne pathogens using standardized culture methods.

The results showed that 9.2% of samples contained Listeria monocytogenes (which causes listeriosis - a serious infection with a 20-30% fatality rate in vulnerable groups). 3.8% contained Salmonella species, and 2.4% contained pathogenic E. coli strains including O157:H7. Overall, approximately 13% of raw milk samples contained at least one dangerous pathogen.

Importantly, contaminated samples were indistinguishable from clean samples in taste, smell, and appearance. Unlike spoiled milk which is obviously off, pathogen-laden raw milk looks and tastes completely normal. Consumers have no way to detect contamination without laboratory testing. The researchers emphasized that even the cleanest farms with excellent sanitation practices cannot guarantee pathogen-free milk at all times, because bacteria can enter milk from the cow''s udder, skin, bedding, or milking equipment.

Published in The Lancet Infectious Diseases in 2023, a historical review examined the public health impact of milk pasteurization since its widespread adoption in the early 20th century.

Before pasteurization became standard practice in the United States (roughly 1920-1940), contaminated milk was responsible for an estimated 25% of all foodborne disease outbreaks. Milk was a primary transmission route for bovine tuberculosis, typhoid fever, scarlet fever, diphtheria, and brucellosis. Combined, these milk-borne infections caused an estimated 65,000 deaths per year in the U.S. at the turn of the 20th century.

Within decades of widespread pasteurization adoption, these diseases virtually disappeared from the milk supply. The review noted that pasteurization is considered one of the ten greatest public health achievements of the 20th century by public health historians. The authors concluded that advocates of raw milk are essentially proposing a return to pre-pasteurization conditions for individual consumers, and that while modern farm hygiene is better than in 1900, the fundamental biology of bacterial contamination has not changed - healthy-looking cows still periodically shed pathogens into milk.