Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
18 Dec

10 Common Arguments Against Dairy Consumption Explored

MilkI’ve celebrated the goodness of dairy fat quite enthusiastically in recent weeks. If you were just joining us, you might have gotten the wrong impression that you’d stumbled into a PR wing of the dairy industry, and that the streets of Mark’s Dairy Apple run whitish-yellow with grass-fed milk fat. No, children aren’t busting open fire hydrants on warm days to dance around in the effervescent spray of kefir, and on winter days it doesn’t rain milk and snow globs of thick Greek yogurt in these parts.

I’m well aware of the darker side to dairy, and today I’ll be exploring the common arguments against dairy consumption. Let’s jump right in:

Grok didn’t drink milk.

True, but the evolutionary argument cannot prove the suitability or unsuitability of a food – it can only generate hypotheses that we can then test or research. The same goes for grain consumption, nighttime artificial light exposure, sedentary living, or any other evolutionary novel activity. It has to be tested.

Takeaway? The relative newness of dairy in the human diet definitely raises concerns about its healthfulness, but it’s not a resounding argument in and of itself.

We’re the only species that drinks the milk of other mammals.

It does seem a bit weird. That’s mankind, though: we do weird things that no other animal could ever conceive of doing. That’s what makes us the top of the food chain. We’re smart and dominant enough to impose our will on nature. It gets us into trouble – see industrial agriculture and artificial trans-fats – but it also improves our station – see the decision of hominids three million years ago to “see how this dead herbivore flesh tastes.” Like the previous argument, this one can only raise hypotheses.

Takeaway? Our species’ departure from, or modification of mammalian norms isn’t always bad. Or good. The specifics matter.

Dairy raises insulin.

It’s true, it does. Both the lactose and dairy proteins exert an insulinogenic effect that when taken in concert rival that of many carbohydrate sources. I actually covered this topic in a post several years ago and found that acute dairy-induced spikes of insulin don’t seem to be related to body fat gain or insulin resistance in healthy people, and that the studies showing a connection between dairy and insulin resistance used skim or low-fat milk, rather than whole. And in athletes trying to recover from training, these insulin spikes may actually promote recovery. Hyperinsulinemia, where insulin is chronically elevated, is another story. If you’re already insulin-resistant, dairy could be problematic.

Takeaway? Dairy’s insulinogenic effect is good for some groups (lean, insulin-sensitive, athletes or trainees looking for muscle recovery), bad for others (insulin-resistant). Context is important.

The betacellulin in dairy can increase cancer.

Betacellulin is a growth factor found in whey that plays an important role in infant growth. In some in vitro studies, isolated betacellulin has been shown to contribute toward the growth of cancer cells. Chris Masterjohn takes apart this argument fairly well, explaining how similar in vitro studies that incorporate conjugated linoleic acid (a trans-fatty acid especially abundant in pastured dairy fat) show that CLA has an inhibitory effect on the promotion of cancer by betacellulin; how most epidemiological studies show no relationship between commercial milk and cancer; how some only support a relationship between low-fat dairy and ovarian and prostate cancer, but not high-fat dairy; and how whole fat milk is actually associated with a lower risk of colorectal cancer.

Takeaway? If betacellulin has cancer-promoting tendencies, it’s probably only when isolated from protective dairy compounds such as CLA and saturated fat. Stick to full-fat, pastured dairy.

Dairy is a general growth promoter and can increase cancer.

Loren Cordain and Pedro Bastos (with a couple other collaborators) released a very interesting paper in which they suggest that rather than being just food, milk is an “endocrine signaling system” whose various components – particularly the proteins – are meant to stimulate hormonally-driven growth in a “species-specific” manner. So human breast milk is perfect for how human babies are supposed to grow and tissue differentiate, cow milk is ideal for calf growth, goat milk for kid growth, and so on. Milk proteins stimulate growth by activating the mTOR pathway and stimulating IGF-1 release. Cordain and Bastos link dairy-induced mTOR activation and IGF-1 release with prostate cancer, citing in vitro and epidemiological evidence that milk consumption during certain developmental phases (prenatal, immediately postnatal, and adolescence) can predispose developing prostates to cancer later in life.

More generally, IGF-1 is a growth promoter which is elevated in childhood – because that’s when people are growing at a fairly steady rate – and in certain types of cancer – because that’s another kind of growth, only unwanted. Since dairy protein consumption is pretty consistently linked to increased IGF-1, it’s easy to assume that dairy can increase cancer risk. Good for growing bodies, bad for growing cancer cells.

So, people with cancer or at risk of cancer should avoid dairy, right? I’m not sure. This study found that a whey protein supplement actually increased the vulnerability of cancer cells to chemotherapy among patients with carcinoma. Another study identified several potential roles for milk proteins in cancer prevention. And there’s the classic tale of Campbell’s rats, where high-casein diets were protective against the development of aflatoxin-induced cancer but increased cancer progression once initiated.

Plus, the mTOR pathway is also where muscle growth happens, which may be why GOMAD (gallon of milk a day) is a popular tactic for strength trainees.

Takeaway? Dairy is a growth promoter, which can be good (muscle) or potentially bad (cancer, particularly prostate when consumed at certain developmental stages). It’s unclear if dairy actually promotes tumorigenesis or promotes growth only once the cancer has been established – or neither.

Dairy increases intestinal permeability, thus allowing proteins and other bioactive compounds entrance into the bloodstream. This can precipitate or exacerbate autoimmune diseases.

For years, I’ve heard that “dairy is designed to increase intestinal permeability.” After all, infants need a bit of a leaky gut to allow absorption of large things like colostrum. It would make sense for milk to increase permeability so this could happen. But it turns out that infant guts are innately permeable, not permeable because of dairy. If anything, it looks like dairy might actually make guts less permeable. I didn’t find any human research to this effect, but I did find some interesting studies with surprising results:

Hydrolyzed casein restored intestinal barrier function and prevented diabetes in a diabetes-prone rat. A later study confirmed these results. A specific casein peptide was also shown to reduce intestinal permeability in another study, and beta-lactoglobulin (another protein component of dairy) had similar effects on intestinal tight junction function. And finally, a component of whey has also been shown to reinforce tight junction integrity.

Yeah, I was surprised too.

That doesn’t mean there aren’t connections, even causal, between dairy consumption and autoimmune diseases like type 1 diabetes, but the presence of leaky gut may be a prerequisite. This would jibe with the observations that people with type 1 diabetesmultiple sclerosisrheumatoid arthritis, and other autoimmune diseases sometimes linked to dairy intake have higher intestinal permeability.

Takeaway? Although these were either rodent or in vitro studies using isolated components of dairy, it seems like the evidence points toward dairy upholding intestinal integrity, if anything. Given existing permeability, dairy proteins can slip through and obviously cause problems, but I’m unaware of evidence showing they increase leaky gut or autoimmune disease on their own absent intestinal permeability.

Dairy has a high acid load, which can lead to bone calcium loss.

I’ve always been skeptical of this one because using the same criteria, meat also has a high acid load on the body. Should we forgo eating meat, which has been shown to improve bone mineral density? Plus, one recent study found that dairy doesn’t actually make the body acidic. Milk and dairy products “neither produce acid upon metabolism nor cause metabolic acidosis.” Further, dairy is a good source of calcium and – particularly in the case of gouda cheese – vitamin K2, both important co-factors in bone metabolism.

Takeaway? Dairy consumption may not ensure or be necessary for good bone health, but it doesn’t seem to negatively impact it.

Dairy contains ample amounts of bioactive hormones which can have negative health effects.

Since a common practice nowadays is the milking of pregnant cows in order to maximize production and estrogen goes up during pregnancy, it seems reasonable to expect elevated levels of estrogen in dairy. Most studies I came across found that some estrogen is present in dairy, with skim milk containing the most bioavailable form of estrogen (conjugated estrogen, the same kind used in oral hormone replacement therapy). For the most part, the amount of active estrogen found in dairy seems too low for physiological relevance. We have too much already in circulation for it to be impacted by dietary sources, some of which will be nullified by digestion.

Dairy proteins can certainly increase IGF-1 (as shown previously) in people, but it’s unclear whether the actual IGF-1 found in dairy has an effect on serum levels. If you’re worried about IGF-1, fermentation takes care of most of it. Stick to fermented dairy like yogurt, kefir, or cheese (which already has health benefits over regular unfermented dairy).

Takeaway? Hormone levels in dairy vary according to production method, pregnancy status of the animal being milked, and chance. For the most part, the amount of hormones in dairy pales in comparison to the endogenous amounts circulating in our bodies at any given time, so even if we had the leakiest gut in the world and everything we ate was absorbed directly into our blood, it would likely have minimal impact on our hormone levels.

Dairy causes acne.

Among food-sensitive acne sufferers, dairy is probably the most commonly reported offender. Indeed, recent studies suggest a connection between skim milk consumption and acne in teenage boys (less so for whole milk) and in girls. Researcher Bodo Melnik points the finger at the mTOR/IGF-1 activating qualities of dairy (and the Western diet at large) as the culprit. It’s a compelling line of argument.

However, one recent study found that fermented dairy enhanced with lactoferrin reduced the incidence of acne, suggesting that dairy isn’t always antithetical to skin health. Raw dairy might work better than pasteurized dairy, since pasteurization destroys the natural lactoferrin content of milk.

Takeaway? Dairy is a common aggravator of acne and is worth removing or avoiding if you have it.

That bovine serum albumin in dairy resembles human collagen type 1 and can increase rheumatoid arthritis through molecular mimicry.

Rheumatoid arthritis patients do seem to produce antibodies to bovine serum albumin, and one case study found that an RA patient achieved relief with cessation of milk consumption and saw symptoms return with resumption. Still, another more recent paper found that BSA antibodies weren’t associated with disease progression or activity (flare-ups) in rheumatoid arthritis, so it’s still theoretical. I would imagine that the problem (if extant) is exacerbated by the presence of leaky gut.

Takeaway? Seems worrisome enough that people with RA might try avoiding dairy, at least as a trial to see how it affects their symptoms. One confounder is that bovine serum albumin is also found in beef muscle meat. RA patients who are reading this: do you notice problems with beef?

Overall, it appears that dairy has both benefits and risks, and that where you fall depends on several factors, like gut health, insulin sensitivity, activity level, age, as well as the quality and form of the dairy (which though I didn’t really get into are implicit when discussing dairy). In other words, it’s extremely variable and personal.

What do you think, folks? Any other anti-dairy arguments out there? Let me know in the comment section!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I think it is important to make the distinction between the value of raw organic grass fed milk and pasteurized, homogenized, confinement raised milk. They are entirely different products and should never be confused as being the same thing. I drink a small amount of grass fed raw milk and don’t touch the pasteurized rubbish. I notice even the raw milk can make me gain weight very easily if i have too much so I keep it very moderate but my family enjoy fairly ample amounts and are fine.

    chris wrote on December 22nd, 2013
  2. It seems like all the legitmate problems with dairy that mark identified are almost certainly only associated with UNFERMENTED dairy (i.e. milk). Even the case study on rhematoid arthritis, his condition improved because he stopped consuming MILK, not dairy perse.

    It is also worth adding to mark’s comments on the evolutionary argument against milk.
    It is true that dairy is out of synch with our evolution, and it is also plausible that we should not consume dairy in it’s raw natural state because of that. However fermentation transforms milk into a novel food which may then be fit for human consumption, in the same way that we did not evolve to eat raw potatoes, but cooking starchy vegetables transformed then into a novel food which then became a part of our evolutionary diet.

    marcus volke wrote on December 23rd, 2013
  3. That was a difficult article to write and very well documented. Must have taken Mark days to write. My hat is off.

    I can’t drink cows milk: makes me anti-social. But I can drink cow’s heavy whipping cream and I can drink Goat’s milk. I can also eat nearly any type of cheese, depending on what it tastes like.

    Here is something that confuses me. Mark stated that milk consumption was not primal as such. Hmmmmm. Grok didn’t heard animals? I think Mark might have made a booboo. He can be forgiven.

    Todd wrote on December 28th, 2013
  4. >We’re the only species that drinks the milk of other mammals

    Usually.

    http://eatmypotato.com/wp-content/uploads/2010/07/dog_adopts_kitten.jpg

    Al wrote on December 30th, 2013
  5. Thanks for all the insight that you’ve shared about mik. Personally, i’ve gone to almond and coconut milk since going paleo / primal, and many of the reasons are the things that you’ve brought up in the article. As a personal trainer, I’ve tried to explain how milk isn’t always the best fluid to drink after a workout, this gives me more “ammunition” to educate my clients about milk.

    Javier Lozano Jr wrote on January 1st, 2014
  6. I really enjoy your insights Mark, I’d like to share some info I’ve accumulated regarding Milk.

    Contrary to all dairy propaganda, animals milk is taylored to the individual species, Cow’s milk’s for example is formulated to aid a 60LB calf’s transformation into a 600 LB Cow.

    Animal’s milk is in fact liquid meat rich in the wrong proteins for human consumption including caseins which are difficult for humans to digest. These undigested proteins enter the lower intestines where they putrefy and create highly toxic by-products which poison us. Undigested proteins can also enter into systemic circulation provoking allergic reactions.

    In addition, the added antibiotics, steroids, hormones and pasteurization (in some milk) change the milk chemistry making that milk even more damaging. We were meant to consume human’s milk and its essential fats which are taylored to our early development but for no more than the first four years of life.

    Ken M. wrote on January 3rd, 2014
  7. “We’re the only species that drinks the milk of other mammals”

    Look I applaud your enthusiasm but this argument is a bit silly. First of all this argument presumes that all species are equal in intelligence. Second, I have yet to encounter any mammal that if fed cow milk would turn it down. My dog and cats will drink this stuff all day long if I give it to them. They love it. The fact that other animals don’t drink cow milk is simply because they are not smart enough to figure out how to get it from a cow.

    How about this argument…Humans are the only species to go to the bathroom in a heated, enclosed room on a porcelain seat. Hmmm…should we go back to digging a hole in the woods and using grass and leaves to wipe?

    rob wrote on January 20th, 2014
  8. Well, other animals do drink the milk of other species. The theft of milk from lactating seals by gulls has been captured on film a number of times. The gull pecks at the seal pup till it yanks its head away to bawl, at which point the gull gulps furiously at the gushing milk. Feral cats in Baja California do something similar – claw at the nursing pup till it releases the teat, then lap at the milk. The feral cats that do this are healthier and stronger than non-milk-stealing kin.

    https://www.youtube.com/watch?v=i-jJGZijUC4
    Gallo-Reynoso, J.P., and C.L. Ortiz. 2010. Feral cats steal milk from Northern elephant seals. Therya 1:207–212.

    Pigs have been reared for (probably) millennia on the waste products of dairying. Chickens adore milk, fresh or sour. As to cats and dogs being unable to digest milk in adulthood, none of mine have ever had any problems at all.

    Like many others, I think that other animals would readily consume the milk of other species throughout their lives if they could just extract it. I also think that humans throughout time, killing a young animal that had a stomach full of milk, would have eaten the curds with gratitude and enjoyment.

    SuzU wrote on December 14th, 2014

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