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Podcast: Drinking Milk is Linked with Prostate Cancer and Autoimmune Disease

By The Paleo Diet Team
February 27, 2014
Podcast: Drinking Milk is Linked with Prostate Cancer and Autoimmune Disease image

Loren Cordain: Hi. I'm Loren Cordain, Founder of The Paleo Diet movement.

Shelley Schlender: And I'm Shelley Schlender. This is The Paleo Diet Podcast for April 2013.

Dr. Loren Cordain: Coming up, we'll talk about a recent study from my colleague at Harvard, Edward L. Giovannucci, my colleague at UCLA, Simon Liu. They published their work in the Journal of Nutrition. It’s about how drinking milk is associated with prostate cancer.

Shelley Schlender: Loren will also explain why milk is often linked to prostate cancer and other cancers along with autoimmune disease.

Dr. Loren Cordain: Hi Shelley. I think this is really a timely topic, particularly for people in the Paleo Diet community because I think the Paleo Diet community is still somewhat fractionated on whether or not dairy products are part of Paleo. It's always been my position that dairy products typically should not be part of Paleo except used occasionally. You can use butter or cheese or whatever but for the most part, people should try to reduce their consumption of milk, skim milk, yogurt and all other dairy products.

I think butter probably is the least problematic because it doesn't contain any of the proteins that cause the immune reactions that we find in milk products. In yogurt and skim milk and so forth. But this is an important study and it should be an eye opener for people in the Paleo community because it's not just this one study. It's again and again and again, we continue to see this epidemiologic relationship between the consumption of milk and prostate cancer in men. These are huge studies involving tens of thousands, sometimes hundreds of thousands of people over the course of the last decade, they've consistently shown that there is a relationship between milk consumption and prostate cancer.


We can also extend this to other cancers as well. There's a risk for breast and ovarian cancer. Milk is not a good thing. Humans never consumed the milk of another species until very, very recent times, evolutionary. You can't milk a wild animal so until we domesticated animals, you couldn't have any dairy products.

So once again, on an evolutionary time scale, humans have had very little time to adapt to this very unusual food protein.

Shelley Schlender: Well, it was an interesting study because it did confirm that but it confirmed it in two different directions in terms of cancer. This study indicates that skim milk without fat in it is associated with more men getting prostate cancer but whole milk consumption, meaning that the fat is still in the milk is more associated with fatal prostate cancer.

Dr. Loren Cordain: One of the tricky things with epidemiologic studies is these are just associations. We can't really show causality And so if you go back and you look at some of the previous studies that examine dairy consumption, they don't necessarily fall out the same as this one did in which they can say that it's whole milk or skim milk.

I think the jury is still out on whether or not specifically it's whole or skim milk that is causing the problem. My personal feelings are virtually all dairy products except for butter and a few others are associated with it because of a couple of mechanisms.

First off is that dairy products typically tend to have high concentrations of the female hormone estrogen in various forms. There's a potent form of estrogen called estrone. It's high in dairy products, particularly dairy products that are produced in the modern era in which cows are kept pregnant three hundred and twenty days out of the year.


Most mammals don't give milk for the entire time that they have young mammals so dairy farmers attempt to keep their animals in milk over most of the year and this process increases the estrone concentration in the milk and as consumer of cow milk, we end up getting more estrone in our bodies.

We know that estrone particularly in males mechanistically can promote prostate cancer. There's a couple of other mechanisms our group has come up with. Milk drinking increases insulin secretion which also increases another hormone called IGF-1. The element of insulin in IGF-1 are also known mechanisms that promote prostate cancer in men.

Shelley Schlender: Loren Cordain, that's interesting about how milk actually increases or you can say, pushes the pancreas to put out more insulin because some diabetes educators say that's a good thing about milk, It actually means that you can eat more carbohydrates because your body is making more insulin. But I gather that's really only a short term benefit. That extra push to the insulin system and in the long run, it isn't so good for your body to be making extra insulin.

Dr. Loren Cordain: Yeah Shelley, I think that's exactly the point and that's what our research group here at Colorado State has argued over the last decade or so that milk's ability to increase or promote insulin secretion is not a good thing and we believe that it's similar to high glycemic load carbohydrates in that the hormonal profile that occurs with insulin secretion is bad and insulin is a master hormone that elevates multiple other hormones. You mention IGF-1. We know that IGF-1 is a risk factor, not just for prostate cancer but also for breast and colon cancer.


Shelley Schlender: There are those two mechanisms that you have seen, they're both hormonal. The estrogen like quality of milk and also the insulin promoting quality of milk are both things that push toward producing more cancer in a person's body.

Dr. Loren Cordain: That's right Shelley and there are other hormones in milk too. When we think about milk, we kind of look at this nice, pleasant white substance that is good for quote/unquote "everybody". Really, milk is filtered cow's blood and many of the hormones and bio-active peptides that are found in the blood of cows are also found in their milk and we know that milk has numerous adverse health effects, not just in adults, with the risk of prostate, breast, ovarian cancer but also in children.

We know that bovine cow’s milk is a potent risk of type-1 diabetes. One of the factors that we're kind of keying in on as a scientific community is bovine insulin, so what we find, bovine insulin is similar to human insulin. It varies by one or two amino acids. What we find is the immune system of young children build anti-bodies against bovine insulin. When we see children that develop type-1 diabetes early on, they have a high probability of containing these anti-bodies against bovine insulin.

So the $64,000 question is how are they exposed to bovine insulin? Well, when they drink milk, the insulin from cows that's in the milk gets past the gut barrier and causes an immune reaction.

Shelley Schlender: Many people believe that raw milk is less likely to cause problems because raw milk has more enzymes in it that help the milk be more digestible. And if someone has a source of good quality and micro-free raw milk than that might be much more helpful than standard milk. Do you think that could be true?


Dr. Loren Cordain: You know, I've heard that argument brought up many times before. And our feeling is whether you eat raw milk of pasteurized milk, it basically contains the same substances that we suspect are problematic in these cancers as well as in insulin resistance. The composition of raw milk, that protein, the sugar content are very similar to pasteurized milk and processed milk.

Word from our laboratory suggests that it doesn't matter, whether it's raw milk or processed or pasteurized milk. It has the same effect.

A similar question came out about goat's milk versus cow’s milk. They all tend to promote an increase in insulin production. It's somewhat dependent on how the animal is raised. The concentration of estrogen, typically cows have a higher concentrations of estrogen than goats simply because there's a difference in the way they're raised to produce the milk. But still we believe that estrogen levels in goats and other mammals can influence our own blood concentrations.

Shelley Schlender: And then there's bovine growth hormone which has been in the milk supply of the United States since the late 1990s. It looks like the data from this particular study on dairy fats and skim milk and prostate cancer involve people who had been drinking milk before that growth hormone was added to the feed of dairy cows.

It may not be that that's what does this. It may be everything else about milk

Dr. Loren Cordain: The additional growth hormone to our dairy herds in the United States that once again, the attempt was to try to make cows produce as much milk as possible from the least amount of feed over the shortest period of time. The economics that are driving it, the notion that growth hormone itself is problematic.


You know, some people have suggested is or isn't, but one of the problems with growth hormone is it also elevates IGF-1 and we know from meta-analyses which we look at multiple studies of people who drink milk, not just a single study, but all of the randomized control trials as well as epidemiological studies that shows that milk absolutely elevates IGF-1 in everyone.

And whether or not it's a direct effect of the bovine IGF-1, it’s the milk that gets through the gut, or whether it's because the protein and the lactose in cow’s milk stimulate our own IGF-1 is still a contentious issue. We haven't worked that out completely. But what can be said is that if you drink milk or consume dairy products, except for butter, it will elevate your IGF-1 and that's not a good thing.

Shelley Schlender: All right so this study raises a lot of confirmation of what people have been warning about the possible dangers of milk and it also has some mysteries. It's not clear why the whole fat milk might have caused more fatal cancer or been associated with more fatal cancer than the skim milk.

Dr. Loren Cordain: Well, you're right Shelley and the problem with all epidemiological studies like this is there are confounding variables that can interact with milk to change or increase or reduce the level of prostate cancer. I don't think anybody would suggest that prostate cancer is caused singularly by milk. I think what we need to look at is increases in dairy consumption be it skim or whole milk increase the risk but certainly they're not the only factors that are involved in prostate cancer.

You could look at the data involving high omega-6 vegetable oils and you can also see this for a variety of these cancers. So the take home message for Paleo Dieters is that when you consume a Paleo Diet, you're not consuming dairy, you're not consuming grains, and you’re not consuming processed foods with defined sugars. You tend to lower your salt intake. All of these factors help to reduce a risk.


I don't think it's ever been my contention or anyone else's that prostate cancer quote/unquote is caused by dairy. What we can say is that it tends to increase the risk for these types of cancers.

With all cancers, there are what we call initiators and promoters. How dairy works to increase the risk for cancer, we're not completely sure. It looks like it tends to be a promoter.

Shelley Schlender: That does fit with this study because it looks like men's consumption of dairy when they were teenagers had much more impact than it did when they were older. Another part that you mentioned that seems to fit with what they're seeing in the study is that a lot of these men were pouring their milk on their cereal so they were having a combination of dairy and grain together which from what you're saying is not what you'd recommend.

Dr. Loren Cordain: Well, that's exactly right. We know from randomized control trials in humans, a high glycemic load carbohydrate meal can get you even greater insulin secretion so milk on Corn Flakes makes it even worse and milk with a chocolate chip cookie makes the chocolate chip cookie even worse.

Shelley Schlender: And could it also be that since it is a grain and you're concern that grains contain anti-nutrients like lectins that this increases the chance of leaky gut and so if there are proteins in the milk that will start to irritate and inflame and get the immune system all riled up, this is kind of double trouble.

Dr. Loren Cordain: That's exactly right and we think that in the western diet, milk goes along with grain consumption. They go hand in hand and we know wheat contains multiple substance that over the long haul increases intestinal permeability. Increases in intestinal permeability tend to promote chronic inflammation and no cancer be it prostate, breast, colon, can proceed without inflammation.


The $64,000 question is what environmental factors tend to promote chronic low-level inflammation. Not just our group but many researchers from around the world now believe that gut mediated inflammation is really at the base of not just cancer but also heart disease.

Shelley Schlender: Well, thank you for explaining all of this and I'm glad that you still like butter. At least that's good.

Dr. Loren Cordain: Well, you know, butter's cool because it doesn't have any of the proteins or the peptides that we think are involved in all these processes so butter is probably one of the healthiest dairy products you could consume.

Shelley Schlender: I'll give you a pat on the back on this one for being kind to butter.

Dr. Loren Cordain: A pat on the back. Okay Shelley. Thanks so much and I'll be looking forward to the next podcast.

That's all for this edition of Paleo Diet Podcast. Visit my website to find more podcast and hot links to the experts and studies.

Shelley Schlender: Our theme music is by Chapman Stick Soloist Bob Culbertson.

Dr. Loren Cordain: Want to send me questions or comments? Go to

Shelley Schlender: For The Paleo Diet Podcast, I'm Shelley Schlender.

Dr. Loren Cordain: And I'm Loren Cordain.

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