Raw Milk…clean and healthy?

One of my officemates used to date a nutritionist. A nutritionist who has given him some interesting ideas about health foods, including apple cider vinegar and raw milk.

Now Officemate is lactose intolerant, as are many adults of Asian extraction, meaning that he lacks the ability to synthesize the intestinal enzyme lactase and cannot break down milk sugar into its digestible bits, galactose and glucose. Officemate claimed that raw milk is digestible by dairy belly-achin’ folks like him because – miracle of nature! – it contains lactase. Naturally.

My interest piqued, I began to explore the science of raw milk versus commercial milk. How does pasteurization and homogenization affect the disease, nutritional, allergic and intolerance profile of dairy?

Into the literature I plowed and found, well, a lot. Firstly there are a growing number advocacy groups, such as The Campaign for Real Milk, which extol the virtues of raw milk, sometimes a wee bit past what the evidence truly finds. Cures allergies! Puts the kibosh on arthritis! Pasteurization kills babies!

And then, of course we have the FDA and other health organizations that wish to wipe raw milk clean off the planet. Sure it might be marginally better for you, but why risk terrifying bacterial infections? Intriguingly, the FDA has created a Power Point presentation to highlight just how bad raw milk is and the Real Milk Campaign has shot back with its response - references included.

I’ve read every paper I could get my hands on and, honestly, both sides seems a little crazed to me. And crazy hardly ever leads to the whole truth.

Indeed the can of worms is so large I’ll be reporting this in two parts. Today we’ll cover the claims over the cleanliness of raw milk and lactose intolerant digestion. Coming up – allergies, autism, nutritional and vitamin differences between “real” milk and the crap we buy in stores.

The Basics

Let’s start with the basics. Homogenization is a process where milk fat globules are forced through tiny pipes, which breaks up said fat into tiny pieces and prevents the cream from floating to the top.

Pasteurization is the heating of milk to sub-boiling temperatures in a bid to kill off the bad bugs without totally ruining the taste and texture (though of course some would find this statement debatable). There are two ways to pasteurize: normal/classic pasteurization, where milk is heated to 63C for 30 minutes or the high temp short time (HTST) method, where milk is raised to 72 degrees for 15 seconds.

Both methods dramatically reduce the number of disease-causing bacteria, including Campylobacter, Escherichia, Listeria, Salmonella, Yersinia, and Brucella, that are often present in milk. Bad. According to the CDC, more than 300 people in the United States got sick from drinking raw milk or eating cheese made from raw milk in 2001, and nearly 200 became ill from these products in 2002.

This is a mere fraction of national food borne illness – in 2006 there were 1.4 million cases of Salmonella alone – but the FDA argues that it’s enough to warrant suggesting that people do not consume raw milk.

Clean Clean Clean

But many supporters of raw milk point to the fact that raw milk kills bad bacteria all on its own. Which sounds like a load of pants, but it’s sort of true. For example, one 1982 study by Doyle and Roman at the University of Wisconsin-Madison found that Campylobacter jejuni (bad) survived longer in pasteurized milk than it did in raw milk. After about 8 days, most of the bacteria had died in raw, but it took around 14 days to get the same result in pasteurized milk.

Likewise a 1977 study by J. E. Ford from the National Institute for Research in Dairying found that - in human milk - E. coli grew slower in raw versus pasteurized milk, though total levels were roughly the same for both classic pasteurization and HTST after 6 hours.

So raw milk is indeed better than pasteurized milk at fending off bad bacteria. The reason is that heat treatment can kill off good bacteria and denature helpful proteins. One such protein is lactoferrin, a natural milk molecule which is currently being used by some companies as part of an antibacterial product in food manufacturing. But unfortunately, it is heat sensitive: in the 1977 Ford study the authors found that heating human milk above 70C (albeit for 15 minutes) destroyed pretty much all the lactoferrin. Heating to 63C killed off about 65%.

Another potentially good thing ruined by milk processing is xanthine oxidase (XO). In a recent paper from the UK medical journal The Lancet, researchers found that XO in human milk produces nitric oxide, which then hampers the growth of Salmonella and E. coli. According to a 1977 report from the USDA’s Agricultural Research Service, raw milk has more than three times the concentration of XO than processed milk: about 110 micrograms (u) per liter versus 34 ug/l.

Next we have the lactoperoxidase enzyme, which also has potent antibacterial properties. Classic pasteurization cuts down activity by 16%, and HTST by 30% (up to 80% in buffalo milk) though this seems to be an adequate fraction. According to a 2001 study by N.E. Marks at the University of Reading, HTST milk could still do a decent job in quelling bacterial growth. Pasteurization at 80C did denature the enzyme and they found the milk spoil faster.

And lastly we have lysozyme, which again has proven antibacterial power. One 1986 paper by Griffiths and often cited by the FDA found that pasteurization left 70% of lysozyme intact in cow’s milk. A more recent analysis of heat-treatment on buffalo milk found that after both normal and HTST pasteurization, the lysozyme was pretty much nuked.

So overall, pasteurization does indeed decrease the content of natural bacteria-fighting compounds. And that is not even including the added influence of good bacteria, which may out compete the bad bacteria. However, studies directly comparing the growth of bacteria in raw versus heat-treated samples – as opposed to the enzyme quantities left behind - do not find enormous differences. For example, take this 2001 study on the growth of a Listeria bacteria found that both raw and pasteurized milk did about the same.

What’s more, some studies suggest that homogenization and pasteurization might even INCREASE the antimicrobial qualities of milk, specifically lactoferrin and lysozyme, such as this 2006 Italian study.

Milk for the Intolerant?

So what about the raw milk lactase claim. I’ve read this statement countless times over, even in major newspapers. But it’s incorrect. However, raw milk does contain lactic acid bacteria – notably species of Lactobaccili and Lactococci. These bacteria are naturally found in milk and ferment lactose into lactic acid using their handy enzyme B-galactosidase. Lactic acid bacteria are also added to milk to create cultured milk products, such as yogurt. The lactic acid produced gives yogurt its distinctive sour taste.

So while milk itself contains no lactase, its natural bacteria can produce it thereby reducing the tummy upsetting lactose in raw milk. Killing off the lactobaccili – as pasteurization will likely do – means no happy lactose reduction.

But here’s a thought. For there to be significant reduction in lactose via these bacteria, there would also have to be significant quantities of lactic acid – better known as spoiled milk. If your raw milk doesn’t taste sour, it’s probably got plenty of lactose and will probably hurt your tummy.

Even the FDA powerpoint rebuttal from the Campaign for Real Milk says there is little good data on what heat treatment does to microbial lactase and presents only anecdotal evidence that lactose intolerant folks can drink raw milk.

Until I see the double-blind food challenge data showing that raw milk is digestible in lactose intolerant people, I remain particularly unconvinced of this claim (there is one study but it is just comparing homogenized versus not homogenized and found no difference) . Africans and Middle Easterners evolved the ability to digest lactose into adulthood some 10,000 years ago, after they domesticated the cow and started drinking its milk. If raw milk was so digestible all on its own, what is the use of the extended lactase gene? Why did only milk-drinking populations seem to benefit from it?

Deep, Milky Thoughts

Raw milk contains bacteria, both good and bad. Raw milk, which accounts for around 1% of milk sales in the US, contributes very little to the burden of food poisoning in the country. Raw milk comes replete with its own bacteria fighting powers, but in the end is not overwhelmingly better at staving off culture growth. It’s very likely, however, that raw milk is cleaner to begin with, as nearly all raw milk dairies have grass fed cows and far less cramped feeding and milking conditions than giant industrial dairies. It’s also plausible that raw milk is more digestible to people with lactose intolerance, but we are lacking data. If you happen to be one of the lucky folk, why not try a blind taste test at home and see what happens?

So while I remain ho-hum about raw milk as a clean and lactose-intolerant friendly food, as we’ll see in the next article, raw milk DOES show some very tangible health benefits: higher levels of omega-3 fatty acids, higher levels of cancer-fighting conjugated linoleic acid, a bit more vitamins and possibly more calcium…and yes…it may indeed fight allergies. Claims linking pasteurized milk (as opposed to milk in general) to Parkinson’s, autism, ear infections and ADHD, however, don’t stand up to the litmus test that is actual evidence.

Check in next time...until then, I probably won’t be drinking any raw milk. But that’s just because I haven’t got any.