Dear Dietitian,

I have a friend who drinks raw, unpasteurized milk. She claims it has many health benefits and that pasteurization of milk is unnecessary. What do you think?

Jim

Dear Jim,

The consumption of raw milk has gained popularity in recent years, and many people believe it is a healthier alternative to pasteurized milk. Let’s take a look at what science says.

Most of us are familiar with the term pasteurization, which is the process of heating food products like milk to a temperature high enough to kill harmful bacteria. The process was named for its inventor, Louis Pasteur, a French scientist. Pasteurization was created to “kill the diseases” of wine in France (1). Commercial pasteurization of milk began in the US in the early 1900s due to widespread milk-borne illnesses.

In recent years, some advocacy groups claim that pasteurization of milk isn’t necessary and that it kills many beneficial properties inherent to milk. Claims include: vitamins and minerals are destroyed; good bacteria are sacrificed; and the nutritional quality of milk is compromised due to denaturing (changing of structure) of proteins.

A review of studies on the safety of raw milk was performed at Johns Hopkins University in Maryland in 2014 and concluded the “relative risk of individual illness is almost 150 times greater per unit of unpasteurized dairy product, compared to pasteurized.” (2) The most common disease-causing bacteria in unpasteurized milk are E. Coli, Salmonella, Listeria, and Brucella. According to Dr. Pritish Tosh, an infectious disease specialist at the Mayo Clinic, Brucella is a drug-resistant bacterium that can cause brucellosis, an infection that can be severe and affects many areas of the body, including the bloodstream, bones, and joints (3).

Contrary to what can be found on the internet, milk’s nutrient composition is not changed by pasteurization. Milk is a significant source of calcium, protein, and vitamin B12. Vitamins A and D are added to pasteurized milk that is sold commercially. While there are some losses of B12 (<10%), vitamins A and D and calcium are heat stable and maintain their value during pasteurization. Denaturing of protein indeed occurs, but it still retains its nutritional purpose (4).

Are good bacteria lost in pasteurized milk? The data on this issue is conflicting. At any rate, healthy bacteria can be obtained in pasteurized foods like yogurt with live and active cultures and kefir. You may also purchase probiotics but remember, research only supports improvement in digestive problems with probiotics, not overall health.

Finally, it is essential to note that most health organizations recommend infants under the age of one not consume cow’s milk, raw or pasteurized. Their digestive tracts cannot handle the ash in cow’s milk, and if they contract an illness from bacteria in raw milk, their immune systems are not yet fully developed to fight the infection effectively. Babies should consume human breastmilk or formula.

Good health to you!

Dear Dietitian

References 1. https://www.britannica.com/biography/Louis-Pasteur

2. A Literature Review of the Risks and Benefits of Consuming Raw and Pasteurized Cow’s Milk – Davis, Li, Nachman – Johns Hopkins Bloomberg School of Public Health, Center for a Livable Future, Dec 8, 2014 3. https://newsnetwork.mayoclinic.org/discussion/infectious-diseases-a-z-raw-milk-cheese-linked-to-brucellosis/

4. MacDonald LE, Brett J, Kelton D, et al. A systematic review and meta-analysis of the effects of pasteurization on milk vitamins, and evidence for raw milk consumption and other health-related outcomes. J Food Prot. 2001; 74: 1814– 1832