Raw milk and our microbiome

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The claimed benefits of drinking raw milk

Raw milk is often not suggested drinking because pathogens in them can cause a range of diseases such as salmonellosis. However, these potential diseases does not mean that raw milk does not have benefits. According to the Gabriela study, the comsumption of raw milk is inversely associated to asthma, its effecting factor being its whey protein fraction. It is worth noting that pasteurization may cause losses of various vitamins such as vitamin C and vitamin B₁₂. As milk is an excellent source of vitamin B₁₂, pasteurizing it would cause vitamin deficiencies in humans.

Whey proteins are used in humans for muscle building and recovery. The most notable change when pasteurizing occurs in these proteins, as 10-20% of them denature. This denaturation could change the way milk proteins are digested, but it does not alter the nutritional value. Think of it as whether it is milk or yogurt that gets to your stomach, the proteins inside would be digested and utilzed nevertheless, as in the end it’s the same amino acids. Interestingly, casein, which is 80% of milk proteins, is heat stable so is not affected by pasteurization. When it comes to probiotic presence in the gut, as studies show that there is an increase in Lactobacilli and valerate after a 12-week raw milk intake,and pasteurization will eliminate almost all microbial communities, including pathogens and useful bacteria.

Health risks of drinking raw milk

According to CDC, in 20 years, there were 202 outbreaks linked to drinking raw milk, causing 2,645 illnesses and 228 hospitalizations. These illnesses are caused by pathogens found in the milk, the most common and familiar of them E. coli and Salmonella. These organisms aren’t just technically in the cow’s body when producing the milk, but however transmitted to the milk while milking the cows. For example, if teats and other milking equipment was insufficiently cleaned, it can lead to direct contamination of raw milk with pathogens. When storing the collected milk, inappropriate temperature control (such as high temperatures in some geographic areas), can also lead to accelerated growth of pathogens.

Standard Plate Count (SPC) and coliform count is used to measure the cleaness of milk, with SPC a measure of the total number of aerobic bacteria in the milk. High SPC numbers can indicate a dirty milking and packaging process. Raw milk is allowed to have up to 100,000 colony-forming units of bacteria/ mL in SPC testing, and coliforms up to 750 CFU/mL of milk; for pasteurized Milk the limit it would be 20,000 CFU/mL and fewer than 10 CFU/mL for coliforms. For E. coli, the ID 50 is really low so a single drop of contaminated milk would likely give you intestine problems. However, Salmonella has a high ID 50 so therefore drinking raw milk would give you that huge amount of pathogens needed. It is also worth noting that in pasteurized milk, a high ID 50 is almost never reached because the starting population is almost zero: no matter how it duplicates it can’t reach that high of a number.

Outbreaks associated with drinking raw milk

One of the largest outbreaks associated with raw milk took place in between September 2023 and March 2024 in California, with a total of 171 outbreaks associated with Salmonella Typhimurium identified. Among the 171 cases, 70% were among children aged <18 years, and and 18 (82%) of the cases required hospitalization. Common signs and symptoms include diarrhea, fever, stomach cramps, nausea, vomiting, and headaches. The salmonella came from one single cow that was recently added to the herd, and the company had to cease production and recall all diary products related to the milk. Children, with still developing immune systems, are most susceptible to this disease, and it is proved as most people hospitalized were children.

The people who consume raw milk would pose larger public health risks. With current science developing, pasteurized milk has almost no difference in nutrition as raw milk, and in most cases they are fortified with vitamins A, D, iron, and more, giving more nutrient content. The pasteurizing process would only cause a minimal loss of nutrients. Some diseases associated with raw milk, such as E. coli and Salmonella mentioned before, could be transmitted fecal-orally. Therefore, if sewage water isn’t cleaned very well and contaminated streams and lakes, all the people associated with that would be at a high risk of these diseases, posing more healthcare problems. It would be wiser to drink pasteurized milk as it contains more nutrients and be safer for society.