Mythbusting: Is it Safe to Drink Raw Milk?

By Dr. Liji Thomas, MDReviewed by Danielle Ellis, B.Sc.

Raw milk: What is it?
A brief introduction to pasteurization
Nutritional claims
Health risks 
Regulatory perspective 
References
Further reading

Raw milk: What is it?

Raw milk is milk from sheep, goats, or cows that have neither been pasteurized nor homogenized.² Over 3% of Americans now drink raw milk, and 38% to 60% of Americans above the age of two years consume milk overall.^{2,17, 24}

Milk consumption in the USA has become widespread over the last century. However, it has fallen over the last few decades despite pasteurization and mass marketing campaigns. Meanwhile, raw milk demand is steadily increasing as a locally sourced, unprocessed, allegedly nutritionally superior form of milk.^2,17

A brief introduction to pasteurization

Pasteurization of milk is a kill step aimed at destroying all human pathogens by heating every particle of milk to one of the specified time-temperature combinations.¹¹ Pasteurization does not sterilize milk.⁶

Pasteurization was a stopgap measure first adopted in Chicago in 1908 to bring down the rates of endemic tuberculosis and brucellosis transmitted via raw milk transported unrefrigerated from farm to city or from urban farms using swill feeding. ²

Initial opposition was based on concerns that it would distract from fundamentals like dairy hygiene, herd health, and tuberculin testing. Still, by 1950, pasteurization was mandatory in all US states. ² Pasteurization coupled with huge improvements in dairy management reduced the proportion of dairy-related foodborne illnesses from 25% in 1938 to <1% by 2016. ¹⁰

Nutritional claims

Milk contains 18 of 22 essential human nutrients, making it an important source of calcium, vitamin D, and proteins. It supports the growth of bones, teeth, and muscle, among other tissues. It also maintains blood coagulation and nerve function.

Whether raw or pasteurized, milk contains about 12g of carbohydrates, 8g of protein, and 300 mg of calcium per cup. Milk protein is a complete protein containing all nine essential amino acids.

On average, it provides >50% of daily vitamin D intake, 30% of calcium, and >20% of vitamin A, B2, B12, and phosphorus intake.²⁴ Milk is also a source of potassium, vitamin K2, and trace minerals like magnesium, zinc, and iodine, which are often deficient in the average American diet, as is calcium.²²  

Mythbusting: Boosting Your Immune System

Pasteurization significantly reduces vitamin C and B12 levels, besides bioactive molecules, beneficial microbes, and cells.^3,4

Health risks

The controversy about raw vs pasteurized milk consumption must admit some basic facts:

1. Raw milk is dangerous for direct consumption if produced or distributed in contaminated conditions.
2. Raw milk meant for pasteurization is not safe to drink unboiled.
3. Raw milk for direct consumption must be legally produced from healthy animals and in hygienic surroundings, complying with microbial standards that are often stricter than those for pasteurized milk.
4. Pasteurization does not remove chemical contaminants like heavy metals, pesticides, and antibiotics caused by poor herd management.

Pathogens in raw milk can include Mycobacterium bovis (agent of bovine and human tuberculosis), Escherichia coli, Salmonella enterica, Campylobacter species (agents of foodborne illness), and systemic pathogens like Listeria monocytogenes, Yersinia species, Coxiella burnetii, and Brucella species. ² L. monocytogenes is associated with brain infections and stillbirths or miscarriages. ²

According to the Centers for Disease Control and Prevention (CDC), approximately 3,000 deaths occur from foodborne illnesses annually. The CDC estimates a 150-fold and 840-fold higher risk of foodborne illnesses with raw milk compared to pasteurized milk and all dairy products, respectively. 

The CDC reports, “If all milk and cheese consumed were pasteurized, an average of 732 illnesses and 21 hospitalizations would be prevented per year in the United States.”²⁰

Pasteurized milk may still contain pathogens like Staphylococcus aureus, Streptococcus species, and Bacillus as well as aflatotoxins.²³ Downstream contamination of pasteurized bulk-tank milk with L. monocytogenes, Cronobacter species, and STEC remains a major challenge. L. monocytogenes can persist in pasteurization and processing facilities for decades. ^2,10 

Between 1998 and 2008, 46% of foodborne illnesses, 38% of hospitalizations, and 23% of deaths were linked to produce, including leafy vegetables, fruits, and nuts, vs 14%, 16%, and 10% for dairy, respectively. The authors declared, "The largest outbreak in our study was 1,644 Campylobacter spp.–associated illnesses resulting from the consumption of pasteurized milk." ¹⁸

From 1998-2018, outbreaks were traceable to raw and pasteurized fluid milk, causing 2,645 and 2,133 illnesses, respectively. Three deaths each occurred from 228 vs 33 hospitalizations, respectively.⁷

Another USA-Canada study covering 2007-2020 reported 20 and 12 outbreaks, with 449 and 174 cases related to unpasteurized and pasteurized milk, respectively. There were 124 vs 134 hospitalizations, with 5 vs 17 deaths and 5 fetal losses. Most outbreaks due to pasteurized milk or milk products were caused by Listeria, which was responsible for 16 of 17 deaths. ^{6, 17}

Hospitalizations and fatalities are mostly due to L. monocytogenes and Shiga toxin-producing E. coli (STEC), the former commonly from pasteurized milk. ^{6, 17}  

Regulatory perspective

The Pasteurized Milk Ordinance (PMO) covers non-microbially tested processor-quality milk from multiple farms and bulk tanks. Such milk is not of food quality at the origin.¹⁷

In the USA, federal and state laws mandate pasteurization for interstate milk sales. Raw milk sales within states are subject to state laws and are prohibited in 17 states.

In the UK, France, Italy, and Switzerland, but not Canada, raw milk can be sold for direct consumption.⁷ In most Asian countries, raw milk is available for unregulated sale.²

Raw milk can be safely produced and distributed today with systems such as good manufacturing practices (GMP) and hazard analysis critical control points (HACCP).² Relevant measures include biosecurity programs to prevent zoonotic contamination, herd health management, hygienic milking, and distribution, closed mechanical milking systems, rapid cooling, cold chains, and quality controls with regular, frequent microbial testing.²

References

1. Pasteurization (2024). Retrieved from https://www.britannica.com/technology/pasteurization. Accessed on August 15, 2024.
2. Berge, A. C., and Baars, T. (2020). Raw milk producers with high levels of hygiene and safety. Epidemiology & Infection. doi: https://doi.org/10.1017%2FS0950268820000060.
3. Loss, G., Apprich, S., Waser, M., et al. (2011). The protective effect of farm milk consumption on childhood asthma and atopy: the GABRIELA study. Journal of Allergies and Clinical Immunology. doi: https://doi.org/10.1016/j.jaci.2011.07.048.
4. Sozanska, B. (2019). Raw Cow's Milk and Its Protective Effect on Allergies and Asthma. Nutrients. doi: https://doi.org/10.3390%2Fnu11020469. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6413174/.
5. Baars, T., Berge, A. C., Garssen, J., et al. (2019). Effect of raw milk consumption on perceived health, mood and immune functioning among US adults with a poor and normal health: A retrospective questionnaire based study. Complementary Therapies in Medicine. doi: 10.1016/j.ctim.2019.102196. https://pubmed.ncbi.nlm.nih.gov/31780022/.
6. Sebastianski, M., Bridger, N. A., Featherstone, R. M., et al. (2022). Disease outbreaks linked to pasteurized and unpasteurized dairy products in Canada and the United States: a systematic review. Canadian Journal of Public Health. doi: https://doi.org/10.17269%2Fs41997-022-00614-y.
7. Koski, L., Kisselburgh, H., Landsman, L. et al. (2022). Foodborne illness outbreaks linked to unpasteurised milk and relationship to changes in state laws – United States, 1998–2018. Epidemiology and Infection. doi: https://doi.org/10.1017%2FS0950268822001649. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9987020/.
8. Bakar, S. Y. B. A., Salim, M., Clulow, A. J., et al. (2021). Human milk composition and the effects of pasteurisation on the activity of its components. Trends in Food Science and Technology. doi: https://doi.org/10.1016/j.tifs.2021.02.055. https://www.sciencedirect.com/science/article/abs/pii/S0924224421001631.
9. Czank, C., Prime, D. K., Hartmann, B., et al. (2009). Retention of the Immunological Proteins of Pasteurized Human Milk in Relation to Pasteurizer Design and Practice. Pediatric Research. doi: https://doi.org/10.1203/PDR.0b013e3181b4554a. https://www.nature.com/articles/pr2009219.
10. Boor, K. J., Wiedmann, M., Murphy, S., et al. (2017). A 100-Year Review: Microbiology and safety of milk handling. Journal of Dairy Science. doi: https://doi.org/10.3168/jds.2017-12969. https://www.journalofdairyscience.org/article/S0022-0302(17)31055-X/fulltext.
11. Lacey, J. A. (2015). Raw Milk Consumption. Nutrition Today. doi: https://doi.org/10.1097%2FNT.0000000000000108. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890836/#R19.
12. Kapoor, S., Goel, A. D., and Jain, V. (2023). Milk-borne diseases through the lens of one health. Frontiers in Microbiology. doi: https://doi.org/10.3389%2Ffmicb.2023.1041051. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10117966/.
13. Collins, A. B., Floyd, S., Gordon, S. V., et al. (2022). Prevalence of Mycobacterium bovis in milk on dairy cattle farms: An international systematic literature review and meta-analysis. Tuberculosis. doi: https://doi.org/10.1016/j.tube.2022.102166. https://www.sciencedirect.com/science/article/pii/S1472979222000038.
14. Vranjes, A. P., Popovic, M., and Jevtic, M. (2015). Raw Milk Consumption and Health. Srpski arhiv za celokupno lekarstvo. doi: 10.2298/SARH1502087P.
15. Whitehead, J., and Lake, B. (2018). Recent Trends in Unpasteurized Fluid Milk Outbreaks, Legalization, and Consumption in the United States. PLOS Currents. doi: 10.1371/currents.outbreaks.bae5a0fd685616839c9cf857792730d1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6140832/.  
16. Vaillant, A. A. J., Modi, P., and Jan, A. (2024). Atopy. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK542187/.
17. Schmid, R. (2010). The Untold Story of Milk, The History, Politics and Science of Nature's Perfect Food: Raw Milk from Pasture-Fed Cows. Journal of Sustainable Agriculture. doi: http://dx.doi.org/10.1080/10440040903396441. https://www.researchgate.net/publication/248920842_The_Untold_Story_of_Milk_The_History_Politics_and_Science_of_Nature's_Perfect_Food_Raw_Milk_from_Pasture-Fed_Cows_by_Ron_Schmid.
18. Painter, J. A., Hoekstra, R. M., Ayers, T., et al. (2013). Attribution of Foodborne Illnesses, Hospitalizations, and Deaths to Food Commodities by using Outbreak Data, United States, 1998–2008. Emerging Infectious Diseases, 19(3), 407-415. https://doi.org/10.3201/eid1903.111866. https://wwwnc.cdc.gov/eid/article/19/3/11-1866_article#;
19. Van Lieshout, G. A. A., Lambers, T. T., Bragt, M. C. E., et al. (2019). How processing may affect milk protein digestion and overall physiological outcomes: A systematic review. Critical Reviews in Food Science and Nutrition. doi: https://doi.org/10.1080/10408398.2019.1646703. https://www.tandfonline.com/doi/full/10.1080/10408398.2019.1646703#abstract.
20. Costard, S., Espejo, L., Groenendaal, H., et al. (2017). Outbreak-Related Disease Burden Associated with Consumption of Unpasteurized Cow’s Milk and Cheese, United States, 2009–2014. Emerging Infectious Diseases. doi:10.3201/eid2306.151603. https://wwwnc.cdc.gov/eid/article/23/6/15-1603_article#;. 
21. Fast Facts on U.S. Hospitals, 2024. https://www.aha.org/statistics/fast-facts-us-hospitals.
22. Milk. 2024. https://www.betterhealth.vic.gov.au/health/healthyliving/milk#nutrients-in-milk.
23. Calahorrano-Moreno, M. B., Ordonez-Bailon, J. J., Baquerizo-Crespo, R. J., et al. (2022). Contaminants in the cow's milk we consume? Pasteurization and other technologies in the elimination of contaminants. doi: https://doi.org/10.12688%2Ff1000research.108779.1.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8822143/.
24. Sebastian, R. S., Goldman, J. D., Entis, C. W., (2010). Fluid Milk Consumption in the United States. What We Eat In America, NHANES 2005-2006.

Further Reading

• All Foodborne Illness Content
• Foodborne Illnesses / Poisoning
• What are Foodborne Viruses?