About one out of every six individuals who drink raw milk become ill as a result, according to new data from the Minnesota Department of Health. Illnesses incurred include parasitic infections such as cryptosporidiosis and bacterial infections including campylobacter, E. coli and salmonella. During the study, researchers came upon 530 cases of infections resulting from raw milk consumption between the years of 2001 and 2010. At the same time, researchers noted that many more raw milk illnesses go unreported, undiagnosed or unconfirmed by a lab.

Typically, milk is heated in a process known as pasteurization in order to kill bacteria before it’s rapidly cooled. As milk is known to be an effective medium in the growth of microbes, it’s typically thought that unpasteurized milk can be rife with dangerous bacteria. Raw milk does not undergo pasteurization.

The Risk is Too High with Raw Milk

To be precise, the researchers found that 20,502 residents of Minnesota fell ill after drinking raw milk over the course of the study. Although this equates to 17% of those who drank raw milk, it’s important to note that this does not suggest that drinking a glass of raw milk comes with a 17% chance of becoming ill, since the vast majority of those surveyed likely drank raw milk many more times than once during the study. At the same time, the researchers said their new study indicates a far greater risk of falling ill from raw milk than was previously believed.

Those who have the misfortune of falling ill after drinking raw milk typically experience a week of symptoms such as vomiting, stomach cramps and diarrhea, all of which can be severe. Worse still, some individuals never recover and develop chronic diseases such reactive arthritis, joint inflammation caused by bacterial infection, or various nervous system disorders. Roughly 20% of the individuals who became ill during the study experienced complications that could lead to kidney failure.

Finally, the researchers noted that sporadic cases of infection, when added together, greatly outweigh the total number of cases reported during outbreaks. In other words, it makes little sense to assume that raw milk is safe to drink just because an outbreak hasn’t been reported.

Limitations of the Study

The researchers admitted that their study was limited in that it only focused on one area of the U.S., where much of the milk comes from a limited number of suppliers. In addition, it’s possible that some of the infections documented in the study were linked to other sources, such as direct contact with cattle, and not raw milk. Raw milk can only legally be sold in 30 states, so a true nationwide study would be impossible.

So, why do some people drink raw milk in the first place? Taste and health benefits, they claim. While taste is of course a matter of preference, so far there are no conclusive studies indicating health or nutritional benefits for raw milk, though there is mounting evidence that drinking it could be dangerous.

The Bottom Line

Drinking raw milk comes with a significant risk of bacterial or parasitic infection, according to a recent study by the Minnesota Department of Health. The full text of the study is available online in Emerging Infectious Diseases.