Organic Milk and Prostate Cancer

The Link Between Milk and Prostate Cancer

Researchers have expressed concern that since cow’s milk contains estrogens, dairy could stimulate the growth of hormone-sensitive tumors. The thought is that the consumption of dairy products could both “promote the conversion of precancerous lesions or mutated cells to invasive cancer and enhance the progression of hormone-dependent tumors.”

This was initially postulated based on suggestive population-scale data like a 25 fold increase in prostate cancer in Japan since World War II. What was happening to their diets during that period? A 5, 10, and 20 fold increase in eggs, meat, and dairy consumption, respectively, whereas the rest of their diet remained pretty stable.

But diet wasn’t the only major change in Japanese lifestyles over the latter half century. Similarly, even though countries with higher milk consumption tend to have more prostate cancer deaths and countries with lower milk consumption fewer deaths, there could be hundreds of confounding variables. But it certainly does spur interest in studying the possibility.

A recent study from Clemson University represents the other extreme, controlling for as many factors as possible by isolating prostate cancer cells out of the body in a petri dish and dripping cow milk on them directly. The researchers chose organic cow’s milk, because they wanted to exclude the effect of added hormones so that they could test the effect of all the growth hormones and sex steroids found naturally in milk.

They found that cow’s milk stimulated the growth of human prostate cancer cells in each of 14 separate experiments, producing an average increase in cancer growth rate of over 30%. In contrast, almond milk suppressed the growth of these cancer cells by over 30%.

But just because something happens in a petri dish or a test tube doesn’t mean the same thing happens in a person. It’s just suggestive evidence that we can use in a grant application to get money to study actual people. This can be done with a retrospective (looking backward) study where we take prostate cancer patients and figure out what they ate in the past, or a prospective (looking forward) study where we look at people’s diets first and follow them for a few years and see who gets cancer. The looking back kind are typically referred to as case-control studies, because researchers look at cases of cancer and compare their diets to controls. The looking forward kind are often called cohort studies because a cohort of people is followed forward. Then, if we want to get fancy, we can do a so-called meta-analysis, where you combine all the best studies done to date and see what the balance of available evidence shows.

The latest meta-analysis of all the best case control studies ever done on the matter concludes that milk consumption is a risk factor for prostate cancer. And the latest meta-analysis of all the best cohort studies ever done also concludes that milk consumption is a risk factor for prostate cancer. An even newer study profiled in my video, Prostate Cancer and Organic Milk vs. Almond Milk, suggests that milk intake during adolescence may be particularly risky in terms of potentially setting one up for cancer later in life.

Despite hormone-related cancers being among our top killers, as pointed out in the Journal of the National Cancer Institute, “we simply do not know which hormones, and how much, are in the food that we ingest. More effort has been directed at the investigation of illicit use of designer steroids by Olympians and ballplayers than to the investigation of the effect of dietary hormones on cancer and other diseases that affect millions.” A proposal is therefore made to monitor levels of steroid and other hormones and growth factors in all dairy and meat-containing foods, though to date this has not been done.

I touched previously on the prostate cancer data in one of my oldest videos, Slowing the Growth of Cancer. Other factors may play into the link between cancer and dairy consumption including industrial pollutants (Industrial Carcinogens in Animal Fat) and IGF-1 (How Plant-Based to Lower IGF-1?), but for more on the hormones in dairy see:

What about all the studies suggesting milk “does a body good”? See my video Food Industry “Funding Effect”.

-Michael Greger, M.D

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Tilemahos Efthimiadis / Flickr

  • Peter

    I can’t play the video….

    • b00mer

      This is a blog entry only, without a video. However the names of related previously published videos are mentioned within the text and you can view these by clicking on them.

    • AllVegan

      There is no video it is an article.

  • Brian

    Article titled “Organic milk and Prostate Cancer”, yet no mention of organic milk. ALMOND milk only alternative mentioned…

    • vl

      It’s in the fourth paragraph, second sentence “The researchers chose organic cow’s milk…”

    • AllVegan

      The reference is here: “The researchers chose organic cow’s milk, because they wanted to exclude the effect of added hormones so that they could test the effect of all the growth hormones and sex steroids found naturally in milk.” in the 4th paragraph,

    • Organic milk also contains naturally occurring estrogen, the amount is dependent upon the gestation period in which the cow is milked.

  • jj

    What role might the phytoestrogens in soy and other plant based foods have in tumor growth?

  • edie

    Um… doesn’t look like you read the article very carefully. Definitely DOES mention organic milk.

  • Veghed

    I’m wondering if the nuclear bomb hitting japan might have been

    • Veghed

      Linked to cancer increases

      • vegank

        I lost what I’ve just typed I think, the information on the correlation between the atomic bomb, Fukushima etc can be found at : with a lot of conjoint research between the U.S and Japan.
        You can select English or Japanese version of the site at the top right hand corner of the website.
        Another site from Japan confirms Dr G’s report about Dairy , meat, fat may be linked with prostate cancer . They also mentioned calcium, I am not a Dr so unsure of which type. They also mentioned an animal protein called IGF-1 , which is linked with prostate cancer.

  • Sherry

    Has there been any studies using raw milk vs almond milk?

  • David Johnson

    I’ve read (e.g. in an article by Dr. Mirkin – well known sports medicine doctor) that for some reason, there’s no evidence yogurt has the same effect. I’d appreciate hearing from anyone with information on this.

    • Did Dr. Mirkin provide any sources for that claim?

      From what I understand, the main problem with dairy is its signalling proteins–specifically, leucine, which stimulates IGF-1 and mTOR growth signalling.

    • RAslam RD

      Good question! One of my projects as graduate student in nutrition was a review of the literature on dairy foods and prostate cancer risk, so to my knowledge there is some evidence for yogurt but not as much as there is on dairy foods as a group or milk in particular. Many of the studies that look at dairy consumption combine yogurt with other dairy foods and do not analyze it separately. Other studies do look at yogurt separately but have a very narrow range of intake in their study, making it difficult to draw conclusions about risk. To illustrate, I have linked a couple of the larger studies below.

      The Multiethnic Cohort Study did not show an association between yogurt consumption and prostate cancer risk, but the highest grouping of intake was >40 grams per day (less than 1/4 cup).

      In contrast, the EPIC Study did show a significant increase in risk with higher consumption of yogurt (17% increased risk for the highest intake group with a median of 57 grams per day).

      If you are interested, the review I did was published in Oncology Nutrition Connection and you can access it here. The section I originally wrote on yogurt was not included, however, as they were looking for a shorter article and the evidence for yogurt was simply not as robust as other dairy foods.

      • Thea

        RAslam: This post is really helpful because a lot of people have posted questions on NutritionFacts about dairy yogurt in particular as opposed to dairy in general. That’s cool that you have looked into the issue so deeply (or as deep as exists right now). Thanks for sharing.

      • David Johnson

        Thanks very much! Your comments and links are very helpful.

    • Phil Larschan

      Hi David!
      It may be helpful to think of all the health problems created by dairy use rather than specific dairy foods being higher in this or that cancer. The milk protein itself, casein, accounts for 87% of milk is naturally carcinogenic.

      In addition to prostate cancer, dairy causes cardiovascular disease [],
      [[], autoimmune issues, allergy issues, crib death and autism [],hormone issues [], saturated fat, trans-fat
      [], cholesterol,
      hormones [], and

      • David Johnson

        Thanks for the feedback. I agree with you, and am very concerned about prostate cancer. But diary is known to reduce gout flare ups and so for a vegan like me who has had them, it seems natural to think about eating some dairy. I was surprised to read one study that found vegans have higher uric acid levels than meat or fish eaters, and vegetarians the lowest of all dietary types (perhaps because of dairy). Perhaps that was so because many of the vegans in the study were eating refined carbs, but I don’t think this was investigated. Anyway, that’s what sparked my interest in low/no fat yogurt as perhaps the least harmful dairy product overall with one positive benefit for those with gout.

        • ReluctantVegan

          I thought uric acid came from the break-down of proteins…(not carbs)?

          • David Johnson

            Here’s a link to a good description:


            Uric acid comes from the breakdown of purines, not protein. Purines are in DNA/RNA and are the result of the body breaking down cells. But there is a connection to protein – foods high in protein tend to be high in purines. I don’t understand why plant purines are less likel to cause gout flare ups but that’s what Choi found:

            Choi, H. K., K. Atkinson, E. W. Karlson, W. Willett, and G. Curhan. “Purine-Rich Foods, Dairy and Protein Intake, and the Risk of Gout in Men.” N Engl J Med. 2004 350(11): 1093-103.

            Choi, H. K., S. Liu, and G. Curhan. “Intake of Purine-Rich Foods, Protein, and Dairy Products and Relationship to Serum Levels of Uric Acid: the Third National Health and Nutrition Examination Survey.” Arthritis Rheum. (2005). 52(1): 283-9..

        • ReluctantVegan

          Can you share the reference of the study?

    • I’ve just read this meta-analysis of 32 cohort studies published earlier this year. The authors concluded that “high intakes of dairy products, milk, low-fat milk, cheese, and total dietary and dairy calcium .. may increase prostate cancer risk.” They discussed but didn’t state any conclusions on yogurt. The RR for yogurt intake in the five studies they looked at was 1.08 per 100/g day. Interestingly, they found whole milk protective. (RR per 200 g/day . 98) Has anyone on staff looked at this meta-analysis? If so, could you provide some insight?

      • I have been reviewing this meta-analysis in more depth–and want to point out that while the study concluded that whole milk may be somewhat protective, it identified two fairly recent studies showing an association between prostate cancer and risk of progression to fatal disease. See

        • David Johnson

          Thanks for these pointers. I don’t have access to the 32 cohorts study but will read the other one.

  • Stacey Lundqvist

    I am horrified that I encouraged my three children (2 boys an 1 girl) to drink milk when they were growing up (as is the praxis in dairy-traditional Sweden where I live) thinking I was doing the right thing. All that dairy at home and school, thinking it was a good source of calcium, yet this country has the highest rate of osteoporosis in the world.

    Have always bought organic food, even though it is very expensive here and I have very small means. Think food is more important than clothes or anything else you spend money on, as it is an investment in your health. Recently been learning about plant-based diets through my daughter (19) who is vegan and through this site. I make only vegan food when she visits and I like it too. I drink organic soy milk myself now instead of cows milk.

    In general I’ve always eaten very little meat (and nearly always organic). Always said I could easily be a vegetarian since I like all of those vegetarian foods. (Or at least a pescetarian); I grew up right on a little fishing lake in Michigan and like eating fish and love seafood. Haven’t eaten meat in a long time now, but have eaten fish with my boys. I’m scared to death of chicken since I’ve learned more about it. Have been avoiding cheese for a while, but find it’s really tempting,

    My oldest son (21, lives on his own) was influenced to purchase more fruit and vegetables by my daughter. He hasn’t changed the rest of his diet however. He is very physically active and trim but smokes unfortunately (that cough of his really scares me). Though cigarettes aren’t as bad as all the things he used to put in his body and brain, if you get my drift (he’s been clean for over a year), so I can’t push too hard.

    The youngest is 15 (who lives mostly with his father) has some problems with weight gain due to medications and an extremely sedentary lifestyle because of agoraphobia and extrem social anxiety. Been trying to get his father to at least use lower fat dairy products (which my son eats no problem when he’s with me) but my ex-husband doesn’t listen well to others, especially me, and he is not easily convinced of anything. My ex’s father has prostate cancer and his maternal grandfather died from it, so if there are any hereditary factors my boys might not be so lucky.

    I just hope the example my daughter is setting and my own attempts to change my eating habits will influence them in a positive direction. My ex has hypertension so I sent him an article about flax seeds and he seemed very interested, so there is some hopd.

    • Charzie

      Stacey, I think a lot of us understand both your frustration with the misdirection of health based education over the decades and also the current issues surrounding what you now know in relation to reluctant loved ones! At least I do! Though nutrition will probably always be open to it’s areas of debate, so many of the facts get twisted by those with an agenda, and it just makes doing the right thing almost impossible for most people. I decided the best course ultimately, was to simplify to the extreme. It works on all levels for me because it is the cheapest route too! No animals products, and nothing processed…plant products as they come from nature, or mildly processed, as in cooking, fermenting, or simple ways of preserving. If I make bread I even grind my own grain, often sprouted first. A bit more work but also so satisfying on a gut level! (Ha ha, I made a punny!)
      Keep taking the best care that you can of yourself… and whoever else you can, and hope that they get the message. I know this is no help, but you aren’t alone in it!

      • Stacey Lundqvist

        Thanks for your encouragement!

    • I suggest try to find a local farmers market in your area.
      Just punch in the zip code and a list will show up, not only of farmers markets, but farms, meat suppliers etc. (I am not sure if you live in U.S. or not – this site may be limited to U.S.) Sometimes, produce from farmers markets are more reasonably priced. I live on a very limited income, so i understand your frustration and i’ve noticed prices are sky-rocketing where i live. Not a good sign. :(

      I also suggest look to acquire some heirloom seeds. Even if you don’t have land or a yard, produce can be grown in containers and also see if there is a community farm or co-ops in your area. These are merely suggestions, in the end you will make the decisions that work best for you and your family. :-)

      Yes, in time by taking steps yourself in your choices, will play an impact on other people in your life.

      • Stacey Lundqvist

        Thanks for your suggestions. I live in Sweden. Food prices are among the highest in Europe. We have a value added tax (a type of sales tax, included in the sticker price) of 12% on food and 25% on everything else. Also there is a near monopoly with the few grocery store chains. Unfortunately many Swedes have the attitude that you should spend the least amount of your money on food, perhaps because it’s so unreasonably expensive. Of course, organic food is even more expensive. I recently bought organic cauliflower for about $5 a pound.

  • R2D2

    There is at least another meta-analysis supporting the same conclusions (just thought it would be interesting pointing out as it is more recent): It looks at dairy products in general but seems to look each product individually (milk vs cheese, etc).

  • ilse

    Hi, I would like a video about food for childeren (8-10 years old); should they eat meat, dairy, raw milk etc to grow? or what should they eat/supplement to max. there health. Thanks.

    • RJ

      The only way for an optimum healthy life is to consume raw organic foods. All your veggies should be certified organic, your meat should be pastured grass fed, milk should be raw, nuts and seeds should be raw and uncooked. This is how humans lived for thousands of years and how mother nature intended it to be.

      • You post very cogent, well researched statements – kudos. Question: with something being certified ‘organic’ – is that a reasonable assurance, considering organic standards are not enforced? I try to buy local when I can. I knew some local farmers that were selling their produce/meats/products at a local farmer’s market…the FDA threatened to shut down their stands, since they used the term Organic. The farmers were very ethical and proud of their organic products. It’s almost as if the FDA owns the rights to the term Organic. I suggested, to just label their products are pesticide free, hormone free, etc. instead. ;-)

        When i first learned of the industrialized food system (Codex, FDA laughable standards, meat industry, GMO contamination of farmland, acquisition of seed companies from Monsanto and the like, etc) it was disturbing. :O Luckily, farmers are banding together, and defending food freedoms and independence. Buy clean (heirloom seeds! I can’t stress that enough, for anyone that reads this….).

        • peseta11

          USDA is the agency in control of organic certification; FDA considers (at best) proportions of organic ingredients in a processed, labeled product. The Natl Organic Standards Board decides details.
          Whoever hassled the farmers, they were selling their crop as organic without being certified; since the 1990s, that’s a Federal no-no, and so far has stopped a lot of fraud and frustrated some presumably honest but often not-well-informed farmers. If you have faith in a local farmer’s honesty AND knowledge, lack of certification is no obstacle. They just can’t use the word. Some go biodynamic and are certified by Demeter, whose rules differ a bit.

    • Thea

      ilse: Dr. Greger has several videos which discuss health issues regarding children. It is very important to note that none of videos support children eating any meat, dairy or eggs. There’s even one video where Dr. Greger quotes the famous pediatrician, Dr. Spock (sp?) as saying that no dairy is appropriate for children after they are weaned.

      It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes. Here are Dr. Greger’s general nutrition recommendations:

      But you have a fair point that children do have some special needs, and those are not specifically addressed by Dr. Greger’s materials. I think that the site VRG (Vegetarian Resource Group) has some great, well-researched materials regarding how to feed children healthy food. Check out these pages:

      You might also check out materials from the Physician’s Committee For Responsible Medicine (PCRM), which is another wonderfully well-research source for information on healthy eating:

      Hope that helps!

  • Isn’t cow’s milk one of the harder milks for the majority of the population to digest? Also, since organic standards are not really enforced, could some of these issues be attributed to milk that is labelled organic, but in reality not? Organic gives the food companies a reason to jack up the price….but it doesn’t mean they are truly organic. FDA standards are abysmal.

    • peseta11

      Again, the rules are enforced– by NOSB, founded by organic farmers as part of USDA. For a good critique of organics in the US, see Cornucopia’s ranking of nominally organic milks and eggs, and last November yogurts.

  • MaryKay Simoni

    I’d be curious to break it down even more: Was the milk they used pasteurized/homogenized. What about raw milk? Our family gets raw cow’s milk and I am no longer drinking it because I believe it might be causing inflammation and my dh is also doing an experiment and quitting it for awhile, however, my kids still drink some, but I have cut way back for them.

  • RJ

    Organic milk and raw milk are very different. Organic milk, while labeled organic, can still contain pesticides and it is pasteurized (heated to the point where vitamins and nutrition is destroyed) and homogenized (fat globules broken up). Raw milk is not pasteurized or homogenized. Raw milk retains all the natural fat and nutrition which actually help regulate the body and to lose weight. Yes, natural fat can help lose weight. They might as well used factory farm milk in this study. Such a shame to see deceiving studies taking place, misinforming the public. Make sure to drink Raw Milk, not Organic, because big corporations have tainted the “Organic” name.

    • Jim Felder

      All milk is formulated to stimulate growth, especially I would think raw milk. It is not just the hormones that are directly absorbed and remain active in the human body, but also the proteins themselves. Animal studies with isolated casein protein, the primary protein in milk stimulated and promoted cancer growth to such a degree that 100% of the rats who consumed it developed liver cancer. In contrast none of rats feed plant protein, either wheat gluten or soy protein, developed liver cancer. 100:0 ratio! In humans cows milk has been shown to stimulate the production of IGF-1, which plays a central role in the progression of many types of cancer.

      The reason for this different reaction between plant and animal protein is the ratio of amino acids in the different proteins. Animal foods have more sulfur containing amino acids than plant protein, especially milk protein. So it is the very protein in milk that signals the infant mammal to grow, grow, grow! And the growth signal is controlled by the percentage of calories represented by protein. Slow growing animals like humans have milk with only about 5% of calories as protein while very fast growing like rats have milk with 50% of calories from protein. Cow milk runs about 20%-23% protein, and so provides a much stronger growth signaling than human milk. Not surprising really since a 60 lb calf needs to get to be a 600 lb cow in less than a year.

      And all of this is only important to infants. Adult of all mammal species including humans have no need for such growth signaling. When it is still given in adulthood it will still stimulate growth, but often not of the type desired. At the cosmetic level it stimulated the skin and can be the source of acne. At a more important level it stimulates the growth of cancer.

      Mammalian milk raw or pasteurized, organic or not, is definitely a functional food we all need to stay away from as adults.

  • Mats Carlberg

    Well…. if you pour whiskey on prostate cancer cells in a culture, they will probably die. That does, unfortunately, not mean that drinking whiskey will kill a prostate cancer in a human body. Estrogen in milk will probably not make it through the liver (That’s why contraceptive hormones have to be modified to work when taken orally). More interesting in this context may be the increased exposure to dioxins and similar highly stable compounds of which some can mimick the effects of sex hormones. Prostate cancer grows best when nurtured by testosterone, while estrogen may have the opposite effect.

  • JHeuman

    Any sense of who funded the Clemson University study? [In future, would it not seem relevant to include who the funder(s) were of each study?)

    • Joseph Gonzales R.D.

      I am not sure. You can find the study here, but in the actual blog Dr. Greger always gives us the links.

      • JHeuman

        I posted my question because neither the video nor what I can see at the study link provides information about funders of the Clemson University study. So, I’m sorry to say, a response 3 months later which reads “I am not sure” is not helpful.

        • Joseph Gonzales R.D.

          Gotcha! Well thanks for telling me. Forgive the delay it’s just that we receive perhaps 300+ emails a day! Here is the answer to your question:

          “Funding for this study was provided by the Cancer Research
          Fund donated to Clemson University by Mr. and Mrs. James
          Creel and by the Healthcare Genetics Program, Department of
          Nursing, Clemson University”

          • JHeuman

            Many, many, many sincere thanks! It bolsters the study to know the funders are not the type likely to expect skew results.

  • nnmlly

    I would love to know if there has been any work done on other dairy sources (eg butter, and cheese), or is it all milk-focused?

    • Joseph Gonzales R.D.

      Hi nnmlly. These links will send you to everything we have on butter and cheese. All dairy products have lactose, which contain galactose (the sugar found in milk that may be harmful). Yogurt may have a bit less galactose, but it is still there. Milk seems to be the most destructive of the dairy foods, but yogurt and other dairy products like cheese (although the research is mixed), have been associated with increased risk of insulin-like growth factor, which can boost other disease risks like cancer. Another study shows higher intake of lactose (equivalent of 3 glasses of milk per day) may be associated with ovarian cancer risk. So yes, lots on milk, but still plenty of studies that lump dairy protein together showing a connection between lots of dairy products and cancer risk. For example, this study found high intake of dairy protein and calcium from dairy products and high serum concentration of IGF-I were associated with an increased risk of prostate cancer. Perhaps it’s the amount that matters? Of course these are only observational studies, but they can help identify trends. Hope that helps answer your question. Take a look though some of this and let me know if you further questions.

      Thanks for posting this,

      • nnmlly

        Thank you so much for this reply.

        I live in a very dairy-focused country (New Zealand), but do not buy milk for my family on the basis of the available research (I can’t quite kick my occasional haloumi habit though).

        My child is completely dairy-free due to an intolerance. People often lecture me about giving her a calcium deficiency – the Diary campaign here is so strong, that many people think she should spend her childhood in hospital, unable to breathe, rather then forgo milk.

        I spent some time looking at the literature around calcium requirements and was rather shocked to discover that recommended intakes overlapped with levels known to cause heart problems in some demographics. My conclusion was that recommended intakes were likely higher than needed, and that a clean wholefood diet, heavy on vegetables and devoid of processed crap (along with plenty of outdoors activity) ought to suffice.

        Regardless – this is a happier, healthier home for being milk-free. Thank you for sharing your research.


        • Joseph Gonzales R.D.

          Plant-based milks should be fortified with calcium. Don’t forget the beans and greens! Huge amounts there, as well as sesame seeds, nuts, seeds, even dried fruits like figs, but yes make sure to get enough calcium for the kiddo! Sounds like you’re on the right track :)

          • nnmlly

            Yup – beans, greens, sesame seeds, nuts, seeds, figs all take a front row in her diet. It took a few years to get her to eat all these things voluntarily, but the perseverance was worth it – she happily munches through them as meals or snacks.

            She is four now, and she just made (with a wee bit of chopping help) the salad to go with our dinner, and it has all the above in it!

            Thanks for the reassurance!

  • MilkTeaShake

    i drink milk