Some people who enjoy raw milk also make up false claims that regular milk is more dangerous.

by Brian Dunning

Filed under Alternative Medicine, Fads, Health

Skeptoid Podcast #383

October 8, 2013

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Today we're going to drop by our friendly local dairy farm and pick up a quart or two of what has become among the trendiest of foodie fancies, raw milk. Raw milk comes straight from the cow's udder and into your glass. It hasn't been homogenized or pasteurized and has nature's full complement of fat, making it a scrumptious, creamy treat. But many of its fans aren't satisfied with touting its flavor; they also claim it brings a host of miraculous health benefits hitherto undiscovered by science. Health experts, on the other hand, warn against consuming it in no uncertain terms, claiming that its unpasteurized bacterial load makes it an unacceptable risk. Is one or the other of these positions true, or do the real facts lie somewhere in between?

Some raw milk lovers take their passion very seriously, almost to the point of a religion. It's fine to like something, fine to uphold ideological positions, fine to advocate to others. But it's never OK to invent bad science to defend a position; and unfortunately, it appears that's exactly what some raw milk proponents do. Here are five common arguments that I found being repeatedly made about the supposed evils of regular pasteurized, homogenized milk:

1. Pasteurization destroys milk's nutrients: False.

As we know, regular milk is pasteurized, and this is the key difference between it and raw milk. Heating food to reduce spoilage has been in practice for about a thousand years, even though the mechanism wasn't well understood at first. We now know that heat kills the microbes found in food; including bacteria, fungi, algae, and a whole host of other organisms. Dangerous bacteria, like Salmonella and E. coli, are the most worrisome.

We could sterilize food if we wanted to kill everything in it, but complete sterilization would also cook or destroy the food. It was Louis Pasteur who discovered in 1864 that a much gentler heating for only a short time was sufficient to kill such a high percentage of the microbes that food spoilage was largely mitigated. Today milk is one of many, many foods that are pasteurized to increase their shelf life and safety. There are various processes for doing this, but the net result is that the milk is briefly heated and then cooled again. Opponents say that a side effect of this is to destroy essential nutrients in the milk.

To see whether this is true, we first have to ask "What are these nutrients?" So far, the answer to this has been wanting. The nutrients in milk are mainly energy from fat and lactose, and these are unaffected by pasteurization. Similarly, the molecular structures of proteins and minerals are far too robust to be damaged by the relatively low heat. One fact is that a number of vitamins are found in reduced concentration in pasteurized milk, including vitamins B1, B12, C and E. Though true, it's a fine trade-off, because milk of any kind is a relatively poor source for these vitamins. Vitamin A content is actually increased after pasteurization.

Often, advocates point to the fact that regular milk is fortified with vitamin D as evidence that pasteurization destroys that vitamin, so it has to be re-added. Untrue. Milk is not a source of vitamin D; it's one of many products that are fortified (such as breakfast cereals, orange juice, and baby formula), and have been since rickets was a major public health problem in the 1930s.

Lactobacillus is a bacterium found in our bodies, and also found in cow's milk. Lactobacillus does help with our digestion and the conversion of sugars to energy. And, it is killed by pasteurization. While some raw milk advocates raise alarm over this, there's no need. Lactobacillus thrives and reproduces itself inside our bodies. There is no need to drink milk to get it.

2. Homogenization makes milk less healthy: False.

Raw milk is not homogenized like regular milk. Homogenization is just what it sounds like; making the milk consistent from batch to batch, and making the fat level consistent throughout each serving.

Homogenization is a simple process. The first thing that's done is to mix together milk from different dairies, making it more consistent overall and day to day. The second part is making it consistent throughout. Raw milk separates into a light, fatty layer on top, and a heavier layer on the bottom. Homogenization turns it into an emulsion, in which the fat particles are tiny and evenly distributed throughout the liquid in such a way that they won't separate like raw milk. This is just a matter of forcing it through a fine strain which breaks up the fat chunks into tiny specks. Presto, a homogenous product.

Opposition to the homogenization of milk is manifold, yet so far, unsupported by any good science. Most of it sprang from a mass-market 1983 book, The XO Factor: Homogenized Milk May Cause Your Heart Attack, which put forth a number of fringe hypotheses which were quickly refuted in the medical literature but achieved much more mindshare among the general public. The book claimed, as its title suggests, that the homogenized fat particles were responsible for a lot of heart disease. Other claimed issues included digestion problems, but again, once controlled testing was done, it was found that people claiming hypersensitivity to homogenized milk reported just as many digestion problems no matter what kind of milk they were given.

Raw milk may avoid homogenization, but the result is just a taste preference. No health benefits or detriments have been discerned either way.

3. Unpasteurized raw milk has less bacteria: False.

The whole point of pasteurizing milk is to reduce the dangerous bacteria, obviously; so this claim really had me scratching my head wondering how on Earth someone could have come up with it. Here is an example of one article that claims raw milk is likely to have fewer bacteria than pasteurized milk, this one from a website called "The Daily Green":

...Provided it comes from a reputable farm and has been processed clean, it should arrive with a fairly low bacterial count (all milk, even pasteurized, has some kind of bacterial count). What has been shown with raw milk is that if you introduce pathogens (i.e., bad bacteria) into it, they die off. They think it's because the "good" bacteria (i.e., natural probiotics) that are in the milk naturally kill the bad bacteria — just the way good bacteria in our intestinal tract kill off bad bacteria.

So if I might paraphrase, the claim is that yogurt-style live probiotic bacteria in raw milk kills bacteria like Salmonella and E. coli; but pasteurization kills the probiotics and allows the Salmonella and E. coli to flourish. Fair enough; however, this claim is founded upon two factual errors.

The first error is that probiotics kill bad bacteria. It's true that bacteria do feed on each other a lot of the time, but this is a far messier battleground than the simplistic miracle claim of "good bacteria beat the bad bacteria". In fact, a 2010 study in Sweden found that patients infected with Salmonella did not have improved outcomes when taking probiotics.

The second error is that pasteurization kills only probiotics and not Salmonella and E. coli. In fact, targeting those harmful bacteria is the entire reason for pasteurization. If it kills harmless probiotics as well, no matter; we don't really care about that.

Either way, the evidence is very clear that raw milk carries far greater risk of bacterial infection than pasteurized milk. The Centers for Disease Control and Prevention devotes an entire website to reporting this increased danger:

Among dairy product-associated outbreaks reported to CDC between 1998 and 2011 in which the investigators reported whether the product was pasteurized or raw, 79% were due to raw milk or cheese. From 1998 through 2011, 148 outbreaks due to consumption of raw milk or raw milk products were reported to CDC. These resulted in 2,384 illnesses, 284 hospitalizations, and 2 deaths. Most of these illnesses were caused by E. coli, Campylobacter, Salmonella, or Listeria. It is important to note that a substantial proportion of the raw milk-associated disease burden falls on children; among the 104 outbreaks from 1998-2011 with information on the patients' ages available, 82% involved at least one person younger than 20 years old.

Without qualification, raw milk is substantially more dangerous than pasteurized milk.

4. Raw milk cures all sorts of diseases: False.

It's pretty common to find in the raw milk literature the claim that conditions like eczema, asthma, and allergies are all successfully treated by drinking raw milk. This claim is completely absent from the scientific literature, but alternative medicine journals have asserted on many occasions that the bacteria in raw milk better challenges a child's immune system, and thus protects the child from such conditions. This is exactly how a vaccine works, so really all they're saying is that raw milk is a vaccine against eczema, asthma, and allergies.

There are no vaccines against these conditions — although "allergies" is such a broad category that it's impossible to make any blanket statements. If it were possible to vaccinate against eczema, asthma, and all allergies, then drug companies would have done it decades ago for immense profits, as they've done with the existing vaccines on the market. Make no mistake, medical science would love to be able to prevent these conditions.

5. Grass-fed cows produce safer milk: False.

Most cows are fed grain, since it takes too much land and rare climatic conditions to let cows pasture graze. Although a lot of raw milk sources say that grass-fed cows produce milk that's higher in this vitamin or that vitamin or what have you, the only difference that's been consistently shown is that it contains a higher amount of a fatty acid called CLA, or conjugated linoleic acid. CLA is sold as a supplement in the alternative health industry as a cure for things ranging from cancer to obesity. There are a number of small studies supporting these uses in the alternative medicine literature.

CLA is found in all meat and dairy products, and it is indeed found in higher concentrations in grass-fed animals. But that doesn't necessarily make it a wonder drug. Unlike the alternative medicine literature, the science literature makes almost no mention of CLA outside of animal studies. There's certainly no clear evidence that CLA supplementation has any evident medical benefit, although it certainly isn't going to hurt you. In the real world, the tiny amount of CLA you'd get by drinking grass-fed cows' milk instead of grain-fed is almost certainly insignificant.

Regardless, it cannot be reasonably argued that the milk from grass-fed cows is "safer" than that from grain-fed cows.

The default feedback I'm going to get from this episode is that I am on the payroll of Big Dairy, paid to spread misinformation and put the small, enlightened dairy farmers out of business. The only people who pay me are my listeners, for pointing out bad information like this that can impact public health. Raw milk is indeed a health risk, but from what I've been able to find, it's not a huge one. It certainly puts fewer people in the hospital than bad meat. If you enjoy the flavor and don't mind the limited availability, I say go for it. But please, like it for what it is, and don't make up bad science to fool other people into sampling a potentially dangerous food.



By Brian Dunning

Follow @BrianDunning