Why unpasteurized milk is bad for you

There is a trend right now of consuming unpasteurized beverages, particularly dairy products. The belief is that this practice will improve the immune system, reduce asthma and generally act as a miracle medicine against all evil that could possibly befall the human body. I would like to clarify a few things on the matter.

What is pasteurization?

“Pasteurization” (also spelt pasteurisation) is a method whereby foods or beverages are heated to kill pathogenic (disease-causing) organisms. Today it is most closely associated with dairy products but since it was a Frenchman who invented the method (Louis Pasteur) the original concern was of the preservation of wine. Apparently Pasteur started working on the method during a holiday after being disturbed by the sourness of the Arbois wines.  Wine can turn sour with the help of microbes.

Pasteur realized that if he quickly heated the young wine to 50-60 °C for a few minutes the wine aged much better. Thus the Pasteurization process was born and went on to save millions of lives over the coming years.

“Pasteurization” only means that the food or beverage has been heated for a few minutes. In the case of milk, it says nothing with regard to what the cows eat, how they are treated and what medications they use. Do not confuse “pasteurization” with “organic”.


Milk vat prepped for pasteurization (image credit: James.folsom)

Sterilization is another method of killing off microbes and is often confused with pasteurization. During sterilization the intent is to kill all pathogenic organisms but this treatment involves heating the food or beverage for an extended period of time at very high temperatures. This may cause a lot of foods to taste unpleasant or frankly disgusting. Pasteurization is not as harsh and only aims at reducing the number of pathogenic organisms so that you will not get sick from it.

If I were a microbe I would consider a vat of fresh milk as my dream home; a perfect place to spend my time, to divide, and make a few billion progenies. Milk contains fat, sugars, and proteins together with all sorts of minerals and vitamins – everything you need! This is also why milk is very nutritious to drink for humans. A post on lactose intolerance and milk protein allergy will come later.

Milk. By 4028mdk09 (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Milk (image credit: 4028mdk09)

The cranky rant:

Dairy is the by far most dangerous food product in the U.S. (and elsewhere too). Microbial infections from milk cause three times as many severe cases of illness where hospitalization is necessary than any other food-related outbreak of disease.

Do you want to know what bacteria might grow in that super organic unpasteurized microbial breeding chamber that you have in front of you (and for which you most likely had to pay a lot for)? Here you go:
Tuberculosis, diphtheria, salmonella, brucellosis, scarlet fever, Q-fever, Listeria, Yersinia, Campylobacter, Staphylococcus aureus, and E-coli and many more…

People with a low immune system, babies, pregnant women, and old people should definitely stay away from unpasteurized milk.

"The first and last communion" by Chrisotbal Rojas showing tuburculosis. Cristobal Rojas [Public domain], via Wikimedia Commons

“The first and last communion” by Chrisotbal Rojas showing tuberculosis.

We have pasteurized food and beverages which protects us from all sorts of very, incredibly, disgustingly nasty diseases. Still, some people continue to drink unpasteurized milk because “it is natural”. Well, seriously! SO IS CHOLERA and HEPITITIS A! Would you eat that of your own free will?

In England and Wales 65 000 people died between 1912 and 1937 from tuberculosis that they had contracted from milk. This does not include the people who were infected and then survived. Let us not walk backwards in time. Please!

There is no evidence showing that some bacterial versions of “knights in shining armour” exist in the “raw” milk will kill off the “bad” bacteria. None.

There is no clear evidence that drinking unpasteurized milk will reduce risk for asthma in your child.

Also, let us think this through statistically. If there is a risk of becoming sick from the milk and becoming hospitalized (a significant risk) is it not better to try to avoid that instead of (misguidedly) trying to prevent possible asthma in the future? We cannot even show that this milk does reduce the risk of asthma! In the end you are rejecting something we know for sure for something we are quite sure is not true. Just consider for a couple of moments where the greatest risk lies…just saying… it makes no sense if you think about it.

I am not saying that you will get tuberculosis from unpasteurized milk, only that it is incomprehensible to want to regularly put yourself at risk when there is such an easy fix to it: buy pasteurized organic milk. I think most of my anger stems from the general “but its natural”-argument. It makes me want to bash my head against a wall.

Asthma inhaler (image credit: Magnus Manske)

Asthma inhaler (image credit: Magnus Manske)

Nutritional value and pasteurization

Several studies have shown that there is no relevant nutritional difference between pasteurized and unpasteurized milk other than that vitamin C, B2 and folate were reduced but the starting concentrations of Vitamin C were never high. If you want Vitamin C eat a bloody orange instead! For the other two vitamins, the total effect of this reduction on your total diet is insignificant (see the MacDonald meta-analysis below). Also the statement that unpasteurized milk is better for lactose intolerant people is a load of horseshit. The amount of lactase enzyme in the microbes present in unpasteurized milk is too low to have any significant physiological effects. Lactase is the enzyme that breaks down lactose (“milk sugar”) and is the enzyme which is present in too low concentrations in the people with lactose intolerance. This is a classic example of a when little knowledge can cause large misunderstandings or misconceptions.


Cheese: pure goodness (image credit: Alex Anlicker)

Pasteurization and flavor

There are several different methods of pasteurization depending on the effect you would like to achieve. UHT pasteurization indeed makes the milk taste a bit off in my opinion but it increases the shelf-life incredibly and this might be a very good thing if you live in a warm climate. Normally pasteurized milk tastes good in my opinion. Unpasteurized cheese is much safer than milk due to the low water content (and higher fat). I eat some French unpasteurized cheese, but only because it is so incredibly good and not because I think it will conduct medical miracles in my body.

Time for a latte macchiato!

Science Safely!

...likes her milk pasteurized.

…likes her milk pasteurized.

Claeys, W.L., Cardoen, S., Daube, G., De Block, J., Dewettinck, K., Dierick, K., De Zutter, L., Huyghebaert, A., Imberechts, H., Thiange, P., Vandenplas, Y. & Herman, L., Raw Or Heated Cow Milk Consumption: Review Of Risks And Benefits, 2012 Food Control 31: 251-262.

Wilson, G. S. (1943), “The Pasteurization of Milk”, British Medical Journal 1 (4286): 261, doi:10.1136/bmj.1.4286.261.

*** Meta analysis: MacDonald, L., Brett, J., Kelton, D., Majowicz, S. E., Snedekerr, K., Sargeant, K. M. 2011. 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. Journal of Food Protection. Vol. 74, No. 11: 1814–1832. doi:10.4315/0362-028X.JFP-10-26.

Langer, Adam J.; Ayers, Tracy; Grass, Julian; Lynch, Michael; Angulo, Frederick; Mahon, Barbara. “Nonpasteurized Dairy Products, Disease Outbreaks, and State Laws—United States, 1993–2006” (PDF). http://www.cdc.gov/foodsafety/rawmilk/raw-milk-questions-and-answers.html. Retrieved 11 February 2015.

Braun-Fahrlaender, C. Mutius. E. 2011. Can farm milk consumption prevent allergic diseases? Clinical and Experimental Allergy 41: 29–35.

Pasteurization temperatures: International Dairy Foods Association (IDFA) http://www.idfa.org/news-views/media-kits/milk/pasteurization

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