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Tuesday, October 27, 2009

Milk and Microbes Part 2: A change of tone

Morgan Weber of The Orchard Chronicles contacted me about the part 1 of these connected blog posts, and was both civil and gracious. I admit that the initial tone I had set may appear somewhat adversarial, but my intent, as always, is simply to educate and inform. Morgan has taken down the posting about the "Campaign for Real Milk" down to edit it. I commend him for it. I hope I can help in its clarification.

5. Who was Weston A. Price?

One of the statements in the original "Campaign" article was an attribution that milk "has an unbelievable immune system". Paraphrasing, the idea is that when gallons of raw milk are injected with high amounts of Salmonella, "Staph Aureas", E. coli O157 : H7 and other pathogens, and allowed to sit for a while, the pathogens eventually died off, proof that the raw milk rejects potentially deadly bacteria. This work was credited to researchers from the Weston A. Price Foundation.

Who was Weston A. Price, anyway? And what is the deal with this foundation? Is it a research institution?

Weston A. Price was a dentist who lived in the turn of the 20th century who espoused a belief that sugar not only cause tooth decay, but social and moral decay as well. These conclusions were and are controversial, in part due to some flaws in his design. The Foundation was set up to archive and propagate these beliefs, that a return to an aboriginal diet is better for humanity. Near as I can tell, the Foundation does not conduct or fund any scientific research, rather is built more on activism and lobbying. The quarterly journal they publish isn't peer reviewed nor necessarily recognized as a scientific resource.

Nonetheless, I think the interpretations about the "immune system" in milk likely come from an article written in the Foundation's journal by one Ted Beals, a retired pathologist who is a member of the Michigan Fresh Unprocessed Whole Milk Workgroup called "A Campaign for Real Milk", that is mostly a critique of the article "Does raw milk kill pathogens?" presented by Amanda Rose at the American Veterinary Medical Association conference in 2009. Rose's paper concludes that whatever pathogen killing properties raw milk has is so low as to be unreliable.

Beals' article proceeds to nitpick Rose's article citation by citation, which can be rather tedious, but I'll highlight just one example:

In another cited paper, researchers Massa, Goffredo, Altieri and Natola inoculated seven different strains of E. coli O157:H7 into fresh unprocessed whole milk to determine their fate after days of storage (Letters in Applied Microbiology 28(1):89-92). Like Doyle and Roman, they spiked the milk with extraordinarily high numbers of each pathogen (1,000,000 per ml — Doyle and Roman used 10,000,000 per ml). Even with these huge numbers of pathogens, the E. coli O157:H7 strains failed to grow and died off gradually. Actually, the purpose of this research was not to determine whether the pathogens were being killed, but whether it was acceptable to store milk at 8°C ( 46°F) rather than the standard 5° C (41° F). The authors conclude that the colder temperature should be used as the standard. tive inhibition properties of fresh raw milk. [italics mine]
Here is an excerpt from the abstract from the original Massa et al paper:

...There was essentially no change in the viable population of three EHEC strains for up to 14 d. The remaining four strains showed an increase in population from ³2 log to 3 log cfu ml−1 in a time period of between 9 and 17 d. The results indicate good survival or even multiplication of E. coli O157 : H7 in raw milk when stored at 8 °C and reaffirm the need for pasteurization and holding the milk at >=5 °C. [italics mine]
Note how the exact opposite conclusion is derived by Beals. This type of argument, where looking for incompleteness in the scientific evidence as proof of the counterargument is a logical fallacy commonly employed by creationists and other pseudoscientific movements. By invoking scientific terms and papers, they ride upon the credibility of scientists but really deploy a different message altogether. Of course, writing is also more entertaining when there is a duality to be presented.

Back to pasteurization and raw milk. Cornell University has put together a website that links together many resources behind the science and technology of modern milk production. Fact is, prior to pasteurization, 25% of all food and water borne illnesses can be traced to milk. The implementation of pasteurization has dropped that rate to less than 1%. The antimicrobial compound lactoferrin is naturally found in milk, but is very dilute. But here's the important fact: it is not affected by pasteurization.

In many cases, people will want to consume raw milk regardless of the scientific evidence. The evidence for any health benefits from raw milk is tenuous at best, and the potential public health problems are a proven historical fact, but I also happen to think that individuals have a right to decide what to do with their lives so long as they don't harm someone else in the process. So, go into it with open eyes: consuming unpasteurized milk is a risky activity. Like unprotected sex, or Russian roulette, or skydiving. And people undertake those risks, anyway. Just don't delude yourself (or others) about it.

Thanks for reading.

1 comment:

  1. Hi Dr Ricky. Thanks for the shout out. I'm the Amanda Rose who wrote the paper Beals responds to. At the Seattle AVMA I actually presented another paper on free food choice from a social science perspective (my background). The pathogen-killing paper comes from the raw milk white papers website.

    I respond in detail to Beals here:

    Amanda Rose