A couple weeks back, a debate flared up following my posting about the “poo duel.” It was a recurrence of a discussion that comes up from time to time, namely, how do pathogens fare in raw milk? Or more to the point, do pathogens actually become overwhelmed by the “good” bacteria, the lactic acid, of grass-fed raw milk?

In fact, it seems to be one of the major bones of scientific contention between opponents and advocates of raw milk.

On one side, we have people like Pumendu Vasavada of the University of Wisconsin, who completely rejects that idea.

At the International Association of Food Protection February symposium on raw milk, he argued that raw milk is inherently dangerous because “it is a hospitable substrate” for pathogens.

He also rejected the idea that “good bacteria” are beneficial. “Almost any bacterial species is capable of producing intestinal symptoms if swallowed in sufficient numbers,” he stated.

At the other end of the spectrum, some raw milk advocates have argued that raw milk from cows raised on grass is a terrible medium for pathogens. Naturopath Ron Schmid stated in the first edition of The Untold Story of Milk that “the good bugs the cows naturally harbor are able to kill off potential pathogens such as Salmonella and E.coli 0157.”

And Mark McAfee, owner of Organic Pastures Dairy Co., commissioned a laboratory in 2002 to inject a sample of his milk with pathogens, and concluded that when “pathogens were added to one-milliliter samples of organic raw milk they would not grow. In fact they died off.” That study has become part of the lore of the raw milk movement.

In commentary on my posting about the “Poo Duel,” Amanda Rose published some partial data about the study Organic Pastures commissioned. Others requested the full study, and I have posted it here. Amanda suggested that the results don’t show the pathogens were killed off.

Mark McAfee seems to have backed off his claim posted on the Weston A. Price site, telling me yesterday, “With raw milk by itself, you don’t see the explosion of bacteria…Lactic acid producing bacteria is the safety mechanism that inhibits the growth of the bacteria.” And a revised edition of The Untold Story of Milk eliminates the story of the study.

The lab study OPDC commissioned is really somewhere in between the original claims, and what Professor Vasavada argues. BSK lab inoculateda huge number of cells into the OPDC milk, and then tested to see if the bacteria wouldgrow, die, or stay the same over the shelf life at refrigeration temperatures. The data show that, overall, the number of bacteria stayed the same for these E.coli 0157:H7 and listeria monocytogenes, and declined sharply for salmonella.

A separate study I located from 1982 shows that campylobacter in both raw and sterile milk died off over the course of the refrigerated shelf life. Thus, neither raw nor highly pasteurized milk served as a favorable medium for this pathogen.

It seems as if, bottom line, pathogens don’t thrive in raw milk, but they don’t all necessarily die off sufficiently to ensure certain consumers can’t become ill.

To me, the flareup of this debate is further evidence of the ideological nature of the struggle over raw milk. One side or the other uses partial data to press its case—raw milk is dangerous, or raw milk isn’t dangerous. What this says to me is something I’ve said before, which is that it is possible to become ill from pathogens in raw milk, just as it’s possible to become ill from pathogens in spinach and hamburgers. Raw milk isn’t any more dangerous than many foods we consume that aren’t subject to debate.

It’s time to move on to new avenues of exploration—maybe an updated and more complete version of the studies posted here. Or completely new studies, such as those suggested in comments following the same Poo Duel posting, by Miguel and Steve Bemis. Let’s use ongoing illnesses to learn more about other possible determinants of food-borne illness—perhaps flavorings or colorings or sweeteners or whatever in seemingly ordinary foods; or genetic pre-disposition; or ongoing variations in individual immunity. Let’s expand our thinking, instead of looking for ever elusive “gotchas.”