Pasteurization: What It Does And Doesn’t Do

Pasteurization’s Effect On Risks & Nutrients

In Wednesday’s newsletter, we asked you for your health-related opinions of raw (cow’s) milk, and got the above-depicted, below-described, set of responses:

• About 47% said “raw milk is dangerous to consume, whereas pasteurization makes it safer”
• About 31% said “raw milk is a good source of vital nutrients which pasteurization would destroy”
• About 14% said “both raw milk and pasteurized milk are equally unhealthy”
• About 9% said “both raw milk and pasteurized milk are equally healthy”

Quite polarizing! So, what does the science say?

“Raw milk is dangerous to consume, whereas pasteurization makes it safer: True or False?”

True! Coincidentally, the 47% who voted for this are mirrored by the 47% of the general US population in a similar poll, deciding between the options of whether raw milk is less safe to drink (47%), just as safe to drink (15%), safer to drink (9%), or not sure (30%):

Public Fails to Appreciate Risk of Consuming Raw Milk, Survey Finds

As for what those risks are, by the way, unpasteurized dairy products are estimated to cause 840x more illness and 45x more hospitalizations than pasteurized products.

This is because unpasteurized milk can (and often does) contain E. coli, Listeria, Salmonella, Cryptosporidium, and other such unpleasantries, which pasteurization kills.

Source for both of the above claims:

Characteristics of U.S. Consumers Reporting Past Year Intake of Raw (Unpasteurized) Milk: Results from the 2016 Food Safety Survey and 2019 Food Safety and Nutrition Survey

(we know the title sounds vague, but all this information is easily visible in the abstract, specifically, the first two paragraphs)

Raw milk is a good source of vital nutrients which pasteurization would destroy: True or False?

False! Whether it’s a “good” source can be debated depending on other factors (e.g., if we considered milk’s inflammatory qualities against its positive nutritional content), but it’s undeniably a rich source. However, pasteurization doesn’t destroy or damage those nutrients.

Incidentally, in the same survey we linked up top, 16% of the general US public believed that pasteurization destroys nutrients, while 41% were not sure (and 43% knew that it doesn’t).

Note: for our confidence here, we are skipping over studies published by, for example, dairy farming lobbies and so forth. Those do agree, by the way, but nevertheless we like sources to be as unbiased as possible. The FDA, which is not completely unbiased, has produced a good list of references for this, about half of which we would consider biased, and half unbiased; the clue is generally in the journal names. For example, Food Chemistry and the Journal of Food Science and Journal of Nutrition are probably less biased than the International Dairy Association and the Journal of Dairy Science:

FDA | Raw Milk Misconceptions and the Danger of Raw Milk Consumption

this page covers a lot of other myths too, more than we have room to “bust” here, but it’s very interesting reading and we recommend to check it out!

Notably, we also weren’t able to find any refutation by counterexample on PubMed, with the very slight exception that some studies sometimes found that in the case of milks that were of low quality, pasteurization can reduce the vitamin E content while increasing the vitamin A content. For most milks however, no significant change was found, and in all cases we looked at, B-vitamins were comparable and vitamin D, popularly touted as a benefit of cow’s milk, is actually added later in any case. And, importantly, because this is a common argument, no change in lipid profiles appears to be findable either.

In science, when something has been well-studied and there aren’t clear refutations by counterexample, and the weight of evidence is clearly very much tipped into one camp, that usually means that camp has it right.

Milk generally is good/bad for the health: True or False?

True or False, depending on what we want to look at. It’s definitely not good for inflammation, but the whole it seems to be cancer-neutral and only increases heart disease risk very slightly:

• Keep Inflammation At Bay ← short version is milk is bad, fermented milk products are fine in moderation
• Is Dairy Scary? ← short version is that milk is neither good nor terrible; fermented dairy products however are health-positive in numerous ways when consumed in moderation

You may be wondering…

…how this goes for the safety of dairy products when it comes to the bird flu currently affecting dairy cows, so:

Cows’ Milk, Bird Flu, & You

Take care!