“Consuming raw (unpasteurized) milk poses significant health risks to humans.”

Raw milk is 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. It's important to understand that raw milk can be a source of foodborne illness. While good practices on farms can reduce contamination, they cannot guarantee safety from harmful germs.

From 1998 through 2018, the Centers for Disease Control and Prevention (CDC) documented 202 outbreaks linked to raw milk consumption, resulting in 2,645 people becoming ill and 228 people hospitalized. Additionally, a 2017 study found that unpasteurized dairy products cause 840 times more illnesses and 45 times more hospitalizations than pasteurized products.

Surveys from various countries have monitored the presence of different types of pathogens in raw milk, with prevalence levels as high as 13% for bacteria like Campylobacter jejuni and Listeria monocytogenes. In some studies, almost a third of all milk samples contained at least 1 type of pathogen. Thus, we must assume that raw milk is likely to contain pathogens.

During October 2023–March 2024, California public health officials investigated an outbreak of Salmonella Typhimurium infections linked to raw milk from a California dairy farm. Among 171 cases identified in California and four other states, 70% were among children and adolescents aged <18 years. This outbreak is one of the largest foodborne outbreaks linked to raw milk in recent U.S. history. The median age of reported ill patients was 7 years, and children were those most likely to be hospitalized among all age groups.

Foodborne outbreaks associated with unpasteurised dairy consumption have risen in high-income countries over the period 2000 to 2018. Campylobacter spp., Shiga-toxin producing Escherichia coli, Salmonella spp., Cryptosporidium parvum, Bacillus cereus, Staphylococcus aureus, Yersina pseudotuberculosis, and Toxoplasma gondii are all recognised pathogens for dairy. Unpasteurised milk contains lactic acid bacteria, which naturally inhibit some pathogenic bacteria, but the effects of lactic acid bacteria are insufficient to make unpasteurised milk safe, as some bacteria have a very low infective dose, and small numbers can still make the milk hazardous for consumption.

During October 2023–March 2024, California public health officials investigated an outbreak of Salmonella Typhimurium infections linked to raw milk from a California dairy farm. Among 171 cases identified in California and four other states, 70% were among children and adolescents aged <18 years. This outbreak is one of the largest foodborne outbreaks linked to raw milk in recent U.S. history.

To UVA Health Children's pediatrician Joshua Jakum, MD, the issue is clear-cut. “Raw milk does not resolve lactose intolerance, treat asthma, or improve allergies. Raw milk does not offer any nutritional superiority.” Raw milk can carry a range of diseases, with most outbreaks related to Listeria, Salmonella, E. coli, and Campylobacter. Other illnesses killed by pasteurization include tuberculosis and bird flu, with H5N1 found in raw milk samples.

The biggest health risk associated with raw milk comes from microorganisms and enzymes that can enter the milk at many different points from milking to the sale. Bacteria that commonly cause food-borne illness, such as salmonella, listeria, and E. coli, can be prevented by pasteurizing milk products. One review of 20 years of data on food-borne illnesses related to drinking raw milk found that, in that time frame, 202 outbreaks and 2,645 illnesses were linked to raw milk.

Raw milk that comes straight from the farm is more likely than pasteurized milk to carry harmful bacteria, cautions Rossi. These bacteria can increase your risk for food poisoning and the complications that come with it. Drinking raw milk can also expose you to highly pathogenic avian influenza (HPAI), also known as bird or avian flu.

The CDC's food safety guidance advises against drinking raw milk and directly addresses a claim that has circulated online about using unpasteurized products to build immunity. “CDC recommends against consuming raw milk contaminated with live A(H5N1) virus as a way to develop antibodies,” the agency says, adding that consuming raw milk “could make you sick.”

Although several epidemiological studies suggest that early life exposure to raw cow's milk, together with other factors (farm exposures), may reduce the risk for developing asthma, allergies, or atopy, they do not identify any cause-effect relationships and data are insufficient to allow recommendation of raw milk as a preventive measure for allergic disease.

The CDC estimates the risk of a glass of raw milk causing a disease outbreak is at least 150 times that of a glass of pasteurized milk. Moreover, disease outbreaks associated with raw milk were 13 times more likely to land people in the hospital. However, a large cross-sectional study in Europe found substantial evidence that children who grew up drinking raw milk, instead of boiled milk, were less likely to develop allergies, including asthma and dermatitis, during childhood. More research is needed to determine the effects of raw and pasteurized milk consumption on allergies, and the mechanisms behind these effects.

It was previously believed that raw milk consumption offered no benefits over pasteurized milk and that the risks associated with raw milk were too great to ever reconsider its “reintroduction”. This was the stance taken by most government and food agencies. However, recent research has shown that unpasteurized milk can have positive effects on the immune system through the decreased risk of certain types of allergenic diseases and infections.

Raw milk consumption is broadly understood to pose a significant public health risk as it introduces the consumer to harmful and potentially life threatening bacterial and viral pathogens. This fundamental risk far outweighs any alleged health benefits, many of which are only anecdotally supported and not backed by scientific evidence. Campylobacter jejuni and Listeria monocytogenes account for almost 13% of pathogens found in raw milk batches around the world. Mycobacterium bovis, Brucella and Salmonella are also common sources of raw milk contamination.

Large epidemiological studies have found that raw milk consumption is correlated with: lower rates of asthma and allergies, less eczema, lower rates of ear infections, fevers, and respiratory infections, increased abundance of probiotic Lactobacillus in the gut.

Proponents argue that raw farm raw milk maintains a broad spectrum of beneficial nutrients, enzymes, and bacteria that are typically diminished or destroyed through pasteurization. While raw milk's nutritional benefits are compelling, it can pose risks due to potential contamination by pathogenic bacteria, including Salmonella, E. coli, and Listeria. This reality drives the need for stringent control and robust sanitary protocols on raw milk farms.