Milk is for Babies

milkWhen Arnold Schwarzenegger was asked if he drinks milk, he famously answered that «milk is for babies», implying that it’s not good for adults to consume this white liquid. To most people, this statement probably seems highly controversial, and based on their knowledge, incorrect. They may have been consuming cow’s milk their whole life and have been led to believe that milk is a very healthy food; a belief that has likely been imprinted in them by the dairy industry – which has done a remarkably “good” job of convincing the public that milk is the perfect food, for adults and children alike – and government nutritional agencies – which typically recommend that everyone should consume low-fat dairy products.

Not everyone is on board the ship that holds these beliefs though. Some people, myself included, are a lot more skeptical when it comes to the healthfulness of milk. I actually think Arnold hits the nail on the head with his statement. He may have been half-joking, but the fact is that milk is indeed for babies. There’s no doubt that milk is the perfect food for a growing child. It’s not the perfect food for an adult though.

What role does milk play in the mammalian diet?

The milk of each mammalian species here on Earth was designed by evolutionary forces (e.g., natural selection) to support the growth and development of the young of that species. It was obviously not designed to promote health or longevity in members of another species.

This basic fact is often left out in discussions about milk. Instead of taking a step back and asking what role milk plays in our diet, dietitians typically jump straight into the specifics and examine what types of nutrients and other compounds that are present in the white liquid we call milk.

This approach is very common in nutrition, regardless of what type of food that’s being investigated. This is unfortunate, because this approach doesn’t really give us a good answer as to whether or not it’s healthy to consume the food in question.

The fact that a specific food is high in certain vitamins or minerals or low in certain nutrients that are believed to cause us harm doesn’t necessarily mean that it’s a healthy food. It’s important to see the forest for the trees. If we stand too close to the object under investigation, we’ll be able to closely inspect its composition and details; however, we may be unable to see the big picture of things.

Milk, regardless of what animal species it’s derived from, contains an impressive repertoire of nutrients, growth factors, hormones, and bacteria. These compounds are there for a reason; they didn’t just happen to be there by chance, which seems to be what some people think.

Here’s what a recent review paper had to say about the role milk plays in the mammalian diet:

Milk plays an exceptional role in the beginning of mammalian life and performs its biological function by delivering its amino acid hardware and exosomal microRNA software. These messengers of milk have only one primary mission: to activate and maintain mTORC1-dependent translation and other mTORC1-mediated anabolic effects during the period of postnatal growth and postnatal metabolic programming.

Mammary gland-derived exosomes transmit a sophisticated array of microRNAs that function as a “Trojan horse”, like a retrovirus infection, to “transfect“ the newborn infant with maternal microRNAs that modify infant’s gene expression at the level of posttranscriptional regulation [9,293,294]. In this context, milk is best viewed as each mammalian mother’s nutrigenomic doping system, accelerating postnatal anabolism, cell growth, and cell proliferation of the offspring. (1)

The unique properties of milk

Milk is a very special food. It is produced with the exact purpose of nourishing a growing child. Over evolutionary time, the milk of each species here on Earth has evolved, changing in its composition and nutritional characteristics. These changes have occurred as a result of selective forces acting upon the natural world.

Milk is also an extraordinarily dynamic food: it can change a lot in a very short time. These short-term changes are shaped by mother-child interactions. You may find it surprising to hear, but research has shown that a lactating mother can respond to her child’s needs by altering the production of antibodies and other compounds found in her breast milk (2). This is obviously not something she does consciously, but rather something that occurs naturally as a result of signaling between the mother and child.

This process clearly highlights that milk is a food that’s specifically produced for babies. It is tailored to provide babies with all the nutrients, microbes, and immune-enhancing substances they need to grow into healthy, strong adults that are able to reproduce themselves one day. Because that’s of course the fundamental reason why evolution “bothered” to design a white liquid that provides “everything” that young, fragile infants need to grow and survive in the big, scary world we find ourselves in; it helps them pass on their genes.

“But… I’ve heard that we’ve adapted to drink milk. If I’m not lactose intolerant, why shouldn’t I drink milk?”

I often come across people who make the case that we have adapted to drink milk. In support of this statement, they present evidence showing that a large proportion of the population in many European countries is able to digest lactose without experiencing gastrointestinal distress. In other words, they have a lactose-persistence phenotype.

What a lot of these people fail to recognize is that natural selection doesn’t select for health, but rather for reproductive success. The fact that you’re able to digest and make use of the nutrients in milk without experiencing any acute health problems doesn’t necessarily mean that it’s healthy for you to drink milk.

Lactase-persistence alleles didn’t spread in European populations because those people who were able to digest lactose lived longer, healthier lives than those who weren’t capable of breaking down this milk sugar, but rather because the former had a higher reproductive success than the latter. I.e., they got more surviving offspring.

This isn’t surprising, given that milk is a very nutritious food. Particularly during times of scarcity, it would have been a significant evolutionary advantage to be able to digest milk.

Often, health and reproductive success are linked; but not always. For example, some chronic diseases develop primarily late in life and have little impact on reproductive success. It’s therefore important that we don’t confuse evolutionary fitness with physical fitness. If a trait confers increased reproductive success, it will spread, regardless of how it affects the health of the organism. As we’ll see in the next section, milk consumption has been associated with a range of adverse health effects. Since most of these health effects have little impact on evolutionary fitness, natural selection doesn’t pay them much attention.

Some of the problems with milk

I’ve talked quite a bit about the problems with milk here on the blog in the past. Let’s briefly summarize the core points…

  • Milk has been implicated in the pathogenesis of many chronic diseases and health disorders
    Milk seems to play a role in the pathogenesis of several chronic diseases and health disorders, including heart disease, insulin resistance, acne vulgaris, and Parkinson’s disease (1, 3, 4, 5).
  • Milk is packed with substances that are not a natural part of the adult human diet
    Milk contains a wide range of hormones, bioactive peptides, and other similar compounds, some of which breach the gut barrier and induce adverse health effects (3).
  • Pasteurization and homogenization may change the structure of some of the nutrients found in milk
    Pasteurization and homogenization can force milk casein and fats into new configurations that make the proteins stackable into fibers/amyloids (6). These milk protein fibers may play an important role in diseases such as type I diabetes and Alzheimer’s disease (6).
  • Milk is extremely high in calcium
    Contrary to what dairy lobbyists want you to believe, the fact that milk is very high in calcium could actually be a bad thing, as an abnormally high intake (from an evolutionary perspective) of calcium may cause mineral imbalances and increase the risk of heart attacks, among other things (3). Moreover, several large meta-analyses have shown that calcium intake is not significantly associated with hip fracture risk in women or men (7, 8, 9). One of these analyses even found that calcium supplementation may increase hip fracture risk (8). Yes, calcium is important, but maybe we’re better off getting it from green vegetables?
  • Cow’s milk consumption may adversely affect bone health
    Recent research suggests that regular consumption of milk and other dairy foods may increase the risk of osteoporosis (10). In other words, milk may actually weaken our bones, as opposed to strengthening them.
  • The macronutrient characteristics of milk differ markedly from that of other foods
    Milk (e.g., cow’s milk) is unique in that it contains whey protein, casein, and the disaccharide lactose, as well as many other special nutrients. It’s undoubtedly beneficial for a growing mammal (e.g., a calf) to take in these compounds; however, the scientific research indicates that it’s not beneficial for an adult human, which is not surprising, given that these nutrients are a novel component of the adult human diet. A low intake of these nutrients is unlikely to do much harm; however, a high intake may certainly do. Casein has been shown to trigger opioid-like effects in the brain (one of the main reasons cheese is so addictive) (11, 12); whey is very insulinogenic, may destabilize the gut microbiota, and promote the development of acne vulgaris, among other things; and lactose has been linked with premature cataract formation (3). If that wasn’t enough, milk also contains high concentrations of saturated fat (About 60% of the fat in milk is of the saturated kind).

Milk is a growth stimulant

Another problem with milk that I haven’t talked much about here on the blog in the past has to do with the impact it has on growth and development. Given that milk’s role in the mammalian diet is to support and promote the development of the young, it shouldn’t come as a surprise that milk has been shown to stimulate growth. In children, there’s a strong association between cow’s milk consumption and linear growth. Children who drink a lot of cow’s milk as they grow up tend to become taller than those who don’t (13, 14, 15).

It’s often assumed that this effect is beneficial. After all, we all want strong and tall children. There’s only one (big problem): Cow’s milk wasn’t “designed” to be a health food for the young members of the species Homo sapiens, it was designed to nurture and strengthen calves. I very much question the conventional idea that it’s good for children to drink milk because milk makes them taller.

Unlike what some people think, milk’s effect on growth can’t solely be attributed to its high nutritional value. Milk is capable of activating evolutionary developmental genes, such as FTO and MTOR, which are very important for perinatal programming. This signaling cascade is a natural part of the developmental phase of mammals and helps promote proper growth and development. However, it’s certainly not a natural part of adult life.

A solid body of research suggests that persistent activation of these signaling systems is a major health hazard promoting ageing and early onset of age-related diseases (1, 14).

Here’s what the review paper mentioned earlier had to say about this issue.

Daily consumption of cooled pasteurized milk thus allows excessive intake of milk’s amino acid hardware and milk’s gene-regulatory software, which in a synergistic fashion upregulate mTORC1 signaling enhancing mTORC1-dependent anabolism and mTORC1-dependent mRNA translation. It is becoming apparent that this unnoticed modification of epigenetics by milk consumption has had an enormous impact on modern human nutrigenomics 10,000 years since the Neolithic revolution.

… Permanent overactivation of mTORC1 signaling is the key mechanism driving mTORC1-mediated age-related diseases of civilization [16,17,18,19,67,89,287,293]. … Persistent milk signaling leads to alterations in cell homeostasis, ER stress, cellular malfunctions, organ damage and thus early onset of age-related diseases. (1)

The bottom line

I’d like to finish off with the quote below, which I feel nicely summarizes the main problems with cow’s milk consumption.

Persistent abuse of a developmental nutrient and programming system of another mammal such as Bos taurus, a species whose initial growth rate is four times that of humans, is thus a major pathogenic factor promoting the epidemic diseases of civilization [316]. Wiley was right when she pointed out that persistent cow’s milk consumption is a novel human behavior potentially exerting long-term adverse effects on human health [10]. Taken together: “No milk today, that’s what this message means, the end of obese and Western disease!”. (1)


  1. Great article!
    There’s also the hypothesis that lactase persistance and amylase AMY1 copy is about surviving to toxins rather than extracting nutrients from milk and grains
    I think that reproductive fitness fits with health as long as an animal lives in the wild.
    The grandparents hypothesis explains why humans are able to survive decades after reproductive age.
    Elder people with a good fitness can be very helpful (and even better than youngs, see Kaplan) to hunt and gather and they are really helpful to grow the granchildren.
    Thus; in this case natural selection is about long term health, they are tightly related.
    But, what about farmers? Society turned into a patriarchal system that doesn’t require neither skills to survive in wildness nor a great fitness in late adulthood since they can have 10 sons that work the fields.
    The elder people can be weak and fragile since they are not needed (especially today they are indeed sadly seen like a social burden instead of wise guides).
    If you get a prostate cancer at 65 years old, who cares? In fact, you are a perfect client for Big Pharma, it’s highly appreciated.

    • Thanks for sharing that paper, Alessio! I just scanned through the abstract. Very interesting. I haven’t come across that theory before.

    • benfury22 says:

      The discussion of mycotoxins in that paper is very provocative. The amounts and types of mycotoxins found in our commercial food supply is little understood and usually glossed over entirely. Aside from aflatoxin on peanuts, you almost never hear about it at all. Yet chronic mycotoxicosis may be one of the primary causes of many of the Western diseases. And mycotoxins are found on a variety of starchy food crops. The improvements in health many people find on gluten and dairy free diets may largely be due to reducing their mycotoxin load.

  2. benfury22 says:

    The complete Arnold quote, “Milk is for babies. When you grow up you have to drink beer.” LOL Ah, the Governator. Always good with the one liners.

    • Haha, I know 🙂 But I didn’t feel the second part of the quote was particularly relevant to the post so I left it out. Thanks for sharing it though!

      • benfury22 says:

        You are most welcome!

        And knowing Arnold’s extremely competitive and pranksterish nature, the question still stands whether this was a deliberate piece of misinformation or just a simple quip to make Pumping Iron a funnier movie.

        Bodybuilding lore was full of the growth inducing powers of gallons and gallons of whole milk long before steroids took over the sport. And Arnold jealously guarded his secret arsenal of muscle building and sculpting methods from would-be competitors.

        Was this Loki Arnold the Trickster fooling his bodybuilding rivals?
        Or actor Arnold trying to craft a better script to sell Pumping Iron, the movie?

        I’m sure we’ll never know. Arnold’s stories change over time and separating the myth from the man is now impossible. Quite possibly even to him.

  3. Some primal advocates say that the fact that a food was not available before doesn’t mean that it may not be included in the diet.
    From a logical standpoint it may sounds reasonable, but it’s going to overlook the evolutionary predictive framework that seems to work so well.
    Furthermore, if we take the evolutionary framework TOGETHER with what research suggested so far, it’s not hard to blame milk.
    mRNA seems to actually drive epigenetic patways rather than being just a nutrient, as suggested by Bastos and others.
    Caseins have a structure really similar to gluten, very hard to breakdown and indeed they have a huge crossreactivity with the former and casein-gluten free diets ameliorate the symptoms of autism, schizofrenia and other disorders.
    Dutch people are well known to be the tallest population in the world.
    If we look at their diet is dairy laden.
    But despite the lenght their bones are really fragile.
    One of my friends lives there and he can witness their fragility, with a high percentage of fractures.
    Maasai are an isolated case and pointing out them just for milk overlloks the other healthy features aside diet that follow an evolutionary template.
    How can we know if they might be even better off withou milk?

    • benfury22 says:

      Exactly, Alessio!

      Teasing out a single thing and attributing good or bad attributes to it is darned near impossible sometimes.

      It’s amusing and kind of sad that most of T. Colin Campbell’s condemnation of all “animal protein” comes from his feeding isolated milk casein to rats. Wow. I get it. Isolated milk casein bad. Yeah, that makes sense. But to then extrapolate that to “all animal protein bad”? Uh, Mr. Campbell’s brain has left the building.

      Yes, maybe the Maasai would be better off without milk, Mr. Campbell. But if they eliminated ALL animal protein, they’d have nothing left to eat!!!

      There’s a strong argument to be made for eliminating gluten and casein containing foods. They’ve certainly proven problematic and they don’t fit into an evolutionary template.

  4. Great article, and perfect timing. I was just entertaining the idea of adding milk into my daily intake after cutting it from my DI years ago. I’ve just changed my mind. Currently I enjoy my smoothie with some frozen fruit, mixed greens, ginger kombucha with a vegan and very clean blend of protein powder; I think I’ll stick with that.

    • I’m glad you enjoyed it, jennifer!

      The following quote/saying comes to mind when I think about how the dairy industry has managed to convince the public that cow’s milk is one of the healthiest foods in existence: “If you repeat a lie often enough it become accepted as truth”

      The dairy industry has shown us that it’s easy to create illusions that people believe in. If you got a good marketing strategy and a lot of resources and money, you can convince the public of pretty much anything.

      Our perception of reality is based on what we can see and hear and what the media and other people tell us to be true. Unfortunately, the reality we perceive isn’t necessarily the “true reality”.

      When growing up, I was told that milk and bread were healthy foods that should make up a large part of my daily diet, so naturally, I started believing that it was good for me to drink a lot of milk and eat a lot of bread. It wasn’t until I got older and started investigating things for myself that I realised I had been led astray.

  5. I dont find this article convincing. You talk about “many serious health problems related to consumption of milk” but your choice of sources is extremely weak.One article about suggested link between acne and milk (not even study),one not objective paleo blig,one biased book and article about mtor (like only milk activates mtor and meet miracolously doesnt)

    Its pretty strange considering pubmed has many studies on milk whichvactually dont support your thesis gor example

    Honestly it just looks lke you cherry picked data to prove your point because “milk is non paleo so it has to be bad”

    • I’m skeptical about milk as well. Not because I think that a new food can’t be introduced in the diet of an animal during an evolutionary path. Nevertheless, the framework is really helpful to make is read better the studies we have in our hands.
      Cordain linked hundreds of studies in his article about milk that together with the evolutionary framework arise some good concerns against it.
      We can’t say that meat promote m-tor patways as much as milk.
      Among bodybuilders is well known that milk proteins are far more efficient in building muscle mass and it’s due to their ability to promote growth, that is consistant with the evidence and the linked articles.
      Lactose, galactose, caseins, BCM7 and mrna signaling are clues that can make a proof.
      Said that, I still think that dairy is far less harmful than wheat, soy and any refined flour.
      You can see it from archeological records in Britain where early farmer that ate meat and cheese remained quite healthy until the advent of grains and you can see it among Maasai and some other traditional cultures.
      But they also have many other factors on the lifestyle that build up a huge array of confounding noise.
      It’s at least possible that may be even better off without dairy.
      I remain quite open minded about this nuanced issue but a reasonable voice in my head is telling me to keep dairy as an occasional treat far from being a bulk of my diet. Besides, cheese is really delicious but I can’t understand the need to drink milk.
      If one wants to advocate the former I can understand it but for the latter I can’t…

      • My point is that scientific aproach requires certain methodology. If you formulate hypothesis and use weak evidence to prove it makes your motives questionable and looks like motivated thinking.

        • Alessio says:

          In a blog it’s hardly doable to put hundreds of reference, especially when the job has been already done by Cordain, Bastos and others. If you read their papers you can find hundreds of reference. Besides, science is the new religion. If you wait that “science” finds the unquestionable link between cause and effect, you’ll end up dying off in a glass bowl without doing anything in your life. Ironically, it takes a bad epidemiological evidence to take a crap as truth (red meat issues docet).
          This is mostly because mainstream business can easily manipulate studies, results and conclusions to make people believe their purpose.
          As well written in the latest book by Robb Wolf, we have to make decisions now and about evidence, not waiting for a lifetime in the hope of science (or God) to come in our help.

          • Amokij says:

            I dont work for milk industry,and i dont really care BUT im interested in longevity and i actually know a lot of papers showing that diary is beneficial for many aspects of health.
            Its like with IGF 1 common myth is that its bad for longevity because of cancer but research shows that too low igf is even worse for lifespan (and even more for life quality)than too high.
            If you dont believe in science than you can believe in flat earth aswell.

            Main role of science isnt to show what is right.Its role is to show what is incorrect.

          • Alessio says:

            I perfectly agree that it takes the right amount of IGF1. What is the actual contextualization of the term science anyway? Do you believe in epidemiology, RCTs, their interpretation? Who’s doing that? Who is discussing about the results? One day it seems X and the other Y…
            If you don’t have a framework you won’t go anywhere…

          • Alessio says:

            The mantra “if you don’t believe in science you can believe in flat earth..” perfectly enlights that one has not understand how science works at all… and the brainwashing by the mainstream media…a real scientist doesn’t believe in science!


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