Does drinking milk increase your IGF levels?

milk in glass bottlesSteve writes:

“I have been seeing a lot of information about milk and dairy raising levels of IGF1 in our bodies. The claim is that will increase the growth of cancer cells, particularly in hormonal based cancers like prostate and breast cancer. Apparently, high levels of IGF1 are good if you are growing but less important once you have matured.  Can you put our minds at ease, please? ”

Drinking a lot of milk might raise your IGF-1 levels, but it’s not because of the hormones in the milk itself. Any IGF-1 that may be present in foods such as dairy products is broken down during digestion and doesn’t have any biological effect in humans.  The amount of protein you take in, on the other hand, has a more direct effect on IGF-1 levels.

Dairy contains protein, of course, but so does meat, fish, beans, legumes, and so on.

What does IGF-1 Do?

IGF-1 (insulin-like growth factor-1) is critical to proper growth when we are kids. When we reach adulthood and stop growing (taller, anyway), levels of IGF-1 decline,  but not to zero. The hormone continues to play an important role throughout life, helping to preserve bone and muscle tissue, for example.  (That could explain why a higher protein intake is  associated with stronger bones.)

Growth is a double-edged sword, however. We want to promote the growth of bones and muscles but we certainly don’t want to promote the growth of cancer cells or tumors. There is some epidemiological evidence that shows an association between higher IGF-1 levels in the blood and higher cancer risks. But correlation is not causation. We don’t know whether high IGF-1 levels promote cancer or are an unrelated phenomenon.

Does Dairy Promote Cancer?

I previously reviewed the literature to see if there was a link between dairy intake and breast cancer in humans–and found none. For prostate cancer, men with the highest intake of dairy products (more than 4 servings per day) have a slightly increased risk.

Dairy products–if you choose to consume them–can be a good source of protein and calcium, which help to maintain strong bones and muscles as we age. And when consumed in moderation , they appear to pose little risk of cancer.


20 thoughts on “Does drinking milk increase your IGF levels?

  1. Monica, thank you very much for this information. I particularly like your comment on ‘correlation/association v causation’, which puts things in perspective for me. I think the link to the research you provided is quite a useful conclusion that will help people make informed decisions.

    “It is important to weigh potential benefits of such a recommendation against the potential risks. For example, results of a recent meta-analysis of case–control studies suggested that men with the highest milk consumption have a 68% higher risk of prostate cancer than men with the lowest intakes (20). However, case–control studies are prone to recall and selection bias, which may have resulted in an overestimation of the association. We hypothesized that high intakes of dairy foods and calcium are associated with an increased risk of prostate cancer and examined this hypothesis by performing a meta-analysis of prospective studies” (Prospective Studies of Dairy Product and Calcium Intakes and Prostate Cancer Risk: A Meta-Analysis Xiang Gao, Michael P. LaValley and Katherine L. Tucker.)

    Great to have you in our corner to interpret all this for us.


  2. Wait, you did not do your research. There are peer reviewed double blind studies. I didn’t just pull them out of thin air. Please do your research before publishing false information. Milk and Dairy DOES NOT DO A BODY GOOD:

    Here is just a small selection of these studies:

    • IGF-1 is critically involved in the aberrant growth of human breast cancer cells. (Journal of the National Institute of Health, 1991-3).

    • Estrogen regulation of IGF-1 in breast cancer cells would support the hypothesis that IGF-1 has a regulatory function in breast cancer. (Molecular Cell Endocrinology, March, 99-2).

    • IGF-1 is a potent growth factor for cellular proliferation in the human breast carcinoma cell line. (Journal of Cellular Physiology, January, 1994, 158-1).

    • IGF-1 plays a major role in breast cancer cell growth. (European Journal of Cancer, 29A – 16, 1993).

    • IGF-1 produces a 10-fold increase in RNA levels of cancer cells. IGF-1 appears to be a critical component in cellular proliferation. (Experimental Cell Research, March, 1994, 211-1).

    • IGF-1 accelerates the growth of breast cancer cells. (Science, Vol. 259, January 29, 1993).

    • A strong positive association was observed between IGF-1 levels and prostate cancer risk. (Science, vol. 279, January 23, 1998).

    • IGF-1 can affect the proliferation of breast epithelial cells, and is thought to have a role in breast cancer. (The Lancet, vol. 351, May 9, 1998).

    • IGF-1 strongly stimulates the proliferation of a variety of cancer cells, including those from lung cancer. (Journal of the National Cancer Institute, vol. 91, no. 2, January 20, 1999).

    • IGF-1 is widely involved in human carcinogenesis. A significant association between IGF-1 and an increased risk of lung, colon, prostate, and pre-menopausal breast cancer has recently been reported. (International Journal of Cancer, 2000 Aug. 87:4).

    • A raised level of IGF-1 has been associated with breast cancer for women and prostate cancer for men. (Rosemary Hoskins, Food Fact no. 2, A Safe Alliance Publication, 1998).

    • By continuing to drink [dairy] milk, one delivers the most powerful growth hormone in nature to his or her body (IGF-I). That hormone has been called the key factor in the growth of breast, prostate, and lung cancer. At the very best, or worst, this powerful growth hormone instructs all cells to grow. This might be the reason that Americans are so overweight. At the very worst, this hormone does not discriminate. When it finds an existing cancer, usually controlled by our immune systems, the message it delivers is: GROW! (Robert Cohen, Milk – The Deadly Poison, Argus Publishing, January 1, 1998, ISBN: 0965919609).

    • Several studies have shown powerful associations between IGF-1 and the risk of colon cancer, prostate cancer, and pre-menopausal breast cancer. As a matter of fact, recent evidence indicates that high IGF-1 levels may be more important than other previously reported risk factors for cancer. The pharmaceutical industry is well aware of the increasingly clear association between IGF-1 and cancer. Chemotherapeutic drugs are being developed to block the activity of IGF-1 or enhance the activity of IGF binding protein-3. (Smith, George Davey, et al. Cancer and insulin-like growth factor-I. British Medical Journal, Vol. 321, October 7, 2000, pp. 847-48).

    • IGF-1 has been called ‘plug and play cancer fuel’ by many. Here is what Dr. Sarfaraz K. Niazi (PhD pharmaceutical sciences, University of Illinois, USA) has to say regarding hormones in milk:

    ‘Some dairy milk samples also show noticeable concentration of a growth hormone given to cows to promote their growth and increase milk production. Being fat-soluble, hormones are more concentrated in the cream. Hormones in milk are a serious threat to health because even at very low concentrations, they can cause severe imbalance of our physiologic system. They have also been implicated in many types of cancers and decreased resistance to infections and diseases. Though prohibited in some parts of the world, unscrupulous farmers continue to use hormones. Whatever a cow eats shows up in her udders. The grass, silage, straw, cereals, roots, tubers, legumes, oilseeds, oilcakes, and milk by-products, which contain a variety of chemical additives, make the diet of modern cow. The diet of cows is rife with pesticides, fertilizers, herbicides and traces of heavy metals along with chemicals from spoilage. With each glass of milk shoved down little Jane’s or Johnny’s throat, comes the increased chance of their developing atherosclerosis, cancer, autoimmune diseases, infections and a host of other diseases still unidentified, when they reach adulthood.’

    • Levels of IGF-1 ….have been associated with prostate cancer risk in at least three prospective studies. Both in vitro and in vivo experiments have provided abundant evidence that IGF-1 can promote prostate carcinogens, including the observations that IGF-1 administration induces prostate growth in the rat, and that prostate tumor development in transgenic mouse models is accompanied by elevations in IGF-1 expression. Sources: (i) Gann, Peter H., MD, ScD, Risk Factors for Prostate Cancer, Rev Urol. 2002; 4(Suppl 5): S3–S10. PMCID: PMC1476014. (ii) Pollak M. Insulin-like growth factors and prostate cancer. Epidemiol Rev. 2001;23:59–66.

    • ‘We showed that IGF-1 can completely take the place of growth hormone” in breast tissue. In other words, IGF-1 can trigger cell growth without an outside cue. Estrogen can amplify the cell-proliferating effects seen with IGF-1, both in the breast and prostate. Excess of IGF-1 or estrogen occurs in the presence of the other which can cause breast hyperplasia (cell division on overdrive) putting one at risk for breast cancer.’ (Kleinberg, David L., et al, Growth Hormone and Insulin-Like Growth Factor-I in the Transition from Normal Mammary Development to Preneoplastic Mammary Lesions, Endocr. Rev., Feb 2009; 30: 51 – 74).

    1. Actually, I think I just took my research a little further than you took yours. The data you cite show a correlation between IGF-1 levels and cancer incidence but not a link between dairy consumption and IGF-1 levels. And when we look for a positive association between dairy consumption and breast cancer, we don’t see one. If anything, the opposite.

      2007 American Journal of Clinical Nutrition (5000 subjects in England and Scottland): Childhood dairy intake was not associated with breast cancer risk.

      2007 Cancer Epidemiology (2000 subjects in U.S.): Reduced breast cancer risks were associated with increasing milk consumption from ages 10-29, probably because of the cancer-preventive effects of vitamin D.

      2006 Cancer Causes and Controls (5000 subjects in Italy): Consumption of milk and diary products did not increase breast cancer risk (and, in fact, consumption of skim milk slightly reduced risk).

      2005 Journal of the American College of Nutrition (meta-analysis of 52 different studies): Evidence does not support an association between dairy product consumption and the risk of breast cancer.

      2005 Nutrition and Cancer (study looking back 30 years and across 38 countries): No substantial effect of milk consumption on risk of breast (and other) cancers.

      2004 American Journal of Clinical Nutrition (meta-analysis of 46 studies): No strong association between the consumption of milk or other dairy products and breast cancer risk.

      2002 Journal of the National Cancer Institute (90,000 women followed for 16 years): “We found no association between intake of dairy products and breast cancer in postmenopausal women. Among premenopausal women, high intake of low-fat diary foods was associated with a reduced risk of breast cancer.”

      2002 International Journal of Epidemiology (meta-analysis of 8 prospective studies involving 350,000 subjects in N. America and W. Europe): “We found no significant associations between intake of meat or dairy products and risk of breast cancer.”

          1. Milk and/or protein consumption may be correlated to IGF-1 levels. That appears to be the upshot of these.

    2. So much energy being spent not understanding a whole topic… Thank god you don’t have a website where YOU would publish false information because of poor understanding of physiology on one hand, and therefore of what published data might mean clinically.

      1. As stated in the article, “Any IGF-1 that may be present in foods such as dairy products is broken down during digestion and doesn’t have any biological effect in humans.  The amount of protein you take in, on the other hand, has a more direct effect on IGF-1 levels.” Skim milk is slightly higher in protein than whole milk.

  3. Thanks for this information, I was looking into the claims that milk is a ‘bad’ food and so far the claims don’t match the science. The role of igf1 seemed like a possible reason but should have shed the light on this too.

  4. Even if what you write here is true (I tend to Michelle Irwin’s side), do you really think that adult humans are supposed to drink the breast milk of another species, that is specifically designed to feed THEIR young? Using it for our own “young” is quite absurd a notion, but as adults we especially have no use for/business drinking cow’s, goat’s, or horse’s milk. These milks are not food for homo sapiens. We tear away calves that are still suckling from their mother when we deem them too old, why should we continue to milk this same mother so we can feed on it? This is all probably too philosophical for you or this page. Brushing away logical instincts (i.e. not drinking another species’ milk) is fairly easy when selectively using scientific journals and then proceeding to buy the white gold in sterile bottles in a completely abstract context so we aren’t reminded of that other mother who lost a child so all of humanity could have her and her child’s milk.

    1. Evelien,
      I understand your attempt at logical reasoning for what humans should/should not eat, but simply stating that no other animals do it doesn’t mean it’s automatically bad for humans. It just means it should be more carefully observed, tested, and consumed than other things before getting a green light. There are a lot of things humans consume that would seem illogical to any other species, but seem normal to us simply because it’s what we’ve always known. For example, humans are the only animals that cook food before consumption. We are also the only animals that combine different plants to form medicine that cures diseases. If you find it logical to cook your food and/or take medicine, the you can’t find it illogical to consume milk from another species just because no other species does that. Personally, I agree with you and don’t drink milk because I believe there are healthier ways to get the nutrition found in milk. I don’t, however, base this on the logic that other species don’t do it, therefore it’s bad. There should be some things completely unique to humans, because humans are a completely unique animal. Defining what homo sapiens are “supposed” to consume is more difficult than just looking at what seems normal or logical.

    2. And this is a great point towards having small scale farms instead to industrial ones. I used to be a vegetarian until I realized the issue is with the system, not the product. I now live rurally and my roommate and friends usually milk their animals alongside the calves, they don’t separate them at all.

  5. Justin, that’s the dumbest thing I’ve ever heard. A cow has to be pregnant to produce milk. Cows don’t magically produce milk for us when they’re not pregnant. And when she gives birth we tear the calf away and bottle raise it in a veal crate so we can steal her milk. She has obviously produced milk for her calf – NOT for humans. Nature has already given us the answer and it’s NO, humans are not meant to consume cows milk! It’s for her baby and full of enough powerful growth hormone to grow a 300lb bovine FFS. It’s completely unnatural for people to consume another species milk and it’s causing a *uck ton of health issues for us. Wake the eff up.

    1. I don’t think Nature has a stake in this issue. Did Nature “mean” for wild animals to eat birds’ eggs? Is it unnatural for them to do so? For that matter, Is it unnatural for wild animals to consume fruit (which is obviously produced by the tree in order to produce another tree)?

      The fact that humans discovered that the milk of runimants was a renewable source of nutrition was a “natural” development just like their discovery that rubbing two sticks together allowed them to start a fire and keep warm.

      If you feel it’s unethical to consume milk, that’s a reasonable position. (The position that consuming milk causes widespread health issues is a little wobblier.) But I’m not sure the “unnatural” argument holds much water. Nature doesn’t care what’s right or wrong, only what works.

      1. As a matter of fact, trees are hijacking the digestive tracts of mammals to spread seeds and is a very natural thing.

        Now, I agree that nature does not know right from wrong. But we as humans have this thing called consciousness that bothers us daily, and we can know that growing animals in CAFOs and using their meat and milk in a way we do today is wrong.

  6. Why is it that when vegans lose the scientific argument they become emotional and resort to insults ?

  7. Meat contains IGF1 and many animals are total carnivores therefore it IS natural to consume IGF1. So that destroys the “it isn’t natural” argument.

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