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IGF-1 as One-Stop Cancer Shop

Insulin-like growth factor (IGF-1) is a natural human growth hormone instrumental in normal growth during childhood, but in adulthood can promote abnormal growth—the proliferation, spread (metastasis), and invasion of cancer.

September 25, 2012 |
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Supplementary Info

Sources Cited

Yang SY, Miah A, Pabari A, Winslet M. Growth Factors and their receptors in cancer metastases. Front Biosci. 2011 Jan 1;16:531-8.

Zhang Y, Ma B, Fan Q. Mechanisms of breast cancer bone metastasis. Cancer Lett. 2010 Jun 1;292(1):1-7.

Kleinberg DL, Wood TL, Furth PA, Lee AV. Growth hormone and insulin-like growth factor-I in the transition from normal mammary development to preneoplastic mammary lesions. Endocr Rev. 2009 Feb;30(1):51-74.

Salvioli S, Capri M, Bucci L, Lanni C, Racchi M, Uberti D, Memo M, Mari D, Govoni S, Franceschi C. Why do centenarians escape or postpone cancer? The role of IGF-1, inflammation and p53. Cancer Immunol Immunother. 2009 Dec;58(12):1909-17.

Endogenous Hormones and Breast Cancer Collaborative Group, Key TJ, Appleby PN, Reeves GK, Roddam AW. Insulin-like growth factor 1 (IGF1), IGF binding protein 3 (IGFBP3), and breast cancer risk: pooled individual data analysis of 17 prospective studies. Lancet Oncol. 2010 Jun;11(6):530-42

Rowlands MA, Gunnell D, Harris R, Vatten LJ, Holly JM, Martin RM. Circulating insulin-like growth factor peptides and prostate cancer risk: a systematic review and meta-analysis. Int J Cancer. 2009 May 15;124(10):2416-29.

Gronek, Piotr ; Rychlewski, Tadeusz ; Słomski, Ryszard ; Stankiewicz, Krystyna ; Lehmann, Joanna. Insulin-like growth factor 1. Studies in Physical Culture and Tourism. 2005;12(1).

Piantanelli L. Cancer and aging: from the kinetics of biological parameters to the kinetics of cancer incidence and mortality. Ann N Y Acad Sci. 1988;521:99-109.

CDC Growth Charts. CDC. 2000.


Images thanks to: Danielle Keller via Wikimedia Commons and SanShoot.


Why do centenarians escape cancer?—people who live to be over a hundred years old.

 As we get older… our risk of getting and dying from cancer grows year by year—but, once you hit about 85 90, your cancer risk starts to drop.

Kinda makes sense; I mean if you didn’t get it by then maybe you’re never going to get it. If you live that long maybe it’s a sign that there something special about you. It seems that centernarians are endowed with a particular resistance to cancer. So what’s their secret?

Every day, 50 billion of our cells die. And every day, 50 billion new ones are born. There’s a balance. Otherwise your body would atrophy,—shrink—or get too big and crowded.

Now sometimes we need grow, like when we’re a baby, or that growth spurt around puberty. Our cells don’t get larger when we grow up, they get more numerous. A child's hand may only be made up of about 50 billion cells, and may have to add half trillion or so growing up.

Once we've already grown up we don’t want a lot of extra cells hanging around. We still need our cells to grow and divide—out with the old; in with the new. We just don’t want to be making more cells than we're putting out to pasture. When you’re a kid extra growth can be good; when you’re an adult, extra growth can mean a tumor.

How do our cells know when to tip the scale in favor of more dividing and less dying and when to come back into balance? A key signal is IGF-1, a growth hormone called insulin-like growth factor #1. Levels goes up when you’re s kid so you grow and then comes back down. Should your levels stay a bit too high as an adult, though, there’s this constant message to your cells grow, grow, grow, divide, don’t die, keep going, keep growing. And so not surprisingly, the more IGF-1 you have in your bloodstream, the higher your risk for cancer. More IGF, more prostate cancer… more IGF, more breast cancer;

Of course it’s not the original tumor that tends to kill you, it's the metastases. IGF-1 is a growth factor, it helps things grow, so it helps cancer cells break off from the main tumor, migrate into surrounding tissues, and invade the bloodstream. What do you think helps breast cancer get into the bone? IGF-1… and the liver, IGF1. lung, brain, lymph nodes. IGF-1, helps transform normal cells into cancer cells in the first place, then helps them survive, proliferate, self-renew, grow, migrate, invade, stabilize into new tumors, and even helps hook up the blood supply to the new tumor. IGF-1 is a growth hormone that, makes things grow—that's what it does. But too much growth when we're all grown up can mean cancer.

[Let’s turn next to how we can prevent all this.]

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Kerry Skinner.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

This video seems like a departure from the last 5 videos, which describes an Ex Vivo Cancer Proliferation Bioassay, but those who've seen my full-length presentation Uprooting the Leading Causes of Death know that this all circles around in the end. I've touched on IGF-1 before in Daily Hormonal Interference and Meat Hormones & Female Infertility, but soon you'll know everything you wanted to about it (but may have been afraid to ask!).

If you haven't yet, you can subscribe to my videos for free by clicking here.

For some more context, check out my associated blog posts: Eating To Extend Our LifespanStool Size and Breast Cancer Risk, How Do Plant-Based Diets Fight Cancer?, Animal Protein and the Cancer Promoter IGF-1, and Estrogenic Chemicals in Meat

  • Michael Greger M.D.

    This video seems like a departure from the last 5 videos, which describes an Ex Vivo Cancer Proliferation Bioassay, but those who’ve seen my full-length presentation Uprooting the Leading Causes of Death know that this all circles around in the end. I’ve touched on IGF-1 before in Daily Hormonal Interference and Meat Hormones & Female Infertility, but soon you’ll know everything you wanted to about it (but may have been afraid to ask!).

    If you haven’t yet, you can subscribe to my videos for free by clicking here.

  • Basskills

    How is this different from Human Growth Hormone for muscle building?

    • Toxins

      Its the same hormone actually. The supplement industry for bodybuilders has a very damaging impact on those consuming their products. Little do people know that most of the supplements they take is either useless or harmful.

  • SJS

    IGF-1 seems to be very closely linked to overall dietary protein intake…would be interested to get your thoughts on this..

  • Teresa Amo

    Can’t wait to hear the prevention part of this.

    • Noah

       Me too, I hope there will be some videos on what foods will contain or make the body produce more of this hormone.

  • Massimo

    I guess that in the next videos you are going to show that bovine IGF-1 is identical to human IGF-1, that it survives digestion, and eventually enters circulation to boost the endogenous levels of IGF-1. Which means, cow milk is the best way to promote cancer.

    • JenDiggityDirt

       I hope so. If not identical then similar enough that we cannot discount that cow milk hormone may affect us in similar way. I mean we ARE drinking a milk that is meant to make animals grow. We are animals. The only ones that drink milk into adulthood and the only ones that drink milk from another species, they say. I just can’t believe that if it were a good practice that nature would have just goofed and not made it a natural food for animals. We need to stop thinking we know so much more than what the natural world is screaming at us. I believe our bodies are BEGGING us to stop consuming dairy and the horrible end result of us ignoring them is disease. Animals aren’t as sick as we are in nature and surely much of that is the result of eating their perfect natural diet. We need to just eat our perfect natural diet. There is a bounty out there and dairy isn’t part of it.

      • Ginny


         Re.animals:  they are sick and die young ..because of the polluted environment man has created and because we keep moving their habitat. 

      • Mings

        Read Weston Price: “Nutrition and Degenerative Diseases” it can be found by googling the name of the book and Pottinger-Price.

      • Peakview

        Flawed thinking. Milk is simply not available to adult animals. That is why they don’t drink it. Would it make any sense for adult animals to feed each other? No. They need to get energy from external sources.
        Humans started using diary as soon as they figured out how to get the milk. Sounds pretty natural now. Learning how to make fermented diary products promoted rapid adoption of dairy for even those who are lactose intolerant.
        Dairy demonization has no legs except in our current days of adding in hormones and antibiotics. Take that away and dairy is an excellent food source.

        • VeganLondonMan

          “Would it make any sense for adult animals to feed each other? No.” Well what do you call an adult bovine animal feeding an adult human animal? Makes no sense, Peakview.

    • Toxins

      Actually, the point Dr. Greger is going to make is that its the type of protein consumed that triggers our own liver to upregulate IGF-1 production.

  • Shane Jackson

    A little scary considering all the ads for various supplements in lifting and fitness magazines for IGF-1 precursors and such

  • Rhmentzer

    If IGF-1 promotes growth in children, does a vegen diet slow growth in children?

    • Toxins

      No, a high meat diet has the potential to put children at risk for early puberty, which puts them at risk for chronic illnesses later in life. Children have naturally elevated levels of IGF-1 in their body. Eating vegan does not hamper this level.

  • Darryl

    An astounding chart comparing serum IGF-I levels in children with cancer with levels in age and gender matched controls. From Badr, Mohamed, et al. “Insulin-like growth factor-1 and childhood cancer risk.”Oncology Letters 1.6 (2010): 1055-1060.

    • guest

      This truly is shocking! I couldn’t understand the article very well. Did they say whether the cancer promoted the levels, or were the levels already high from lifestyle or supplements? I know zinc increases igf-1, and some parents worry their kids need vitamins and minerals so they give them multi-supplements which have zinc in them.
      Also, a lot of older men take zinc supplements, ironically to help keep their prostate healthy. Its frustrating how something can be helping and harming at the same time.

      • bob

        So using hgh secretagogues (amino acids, etc.) at an older age would possibly + correlate with cancer incidence? Or is there a reduced correlation at older ages? At one time was selling an IGF-1 supplement….might still do so.

    • Harriet Sugar Miller

      Does insulin or glucose trigger or contribute to IGF-1 production?

      • Darryl

        There’s a weak association with carbs in observational studies. For the most part IGF is how a surplus of complete protein is signalled.

        On cell membranes, there are insulin receptors, IGF receptors, and hybrids of the two, and they all effect similar downstream pathways. Oncologists use the abbreviation IIRF (insulin and insulin-like growth factor I receptor family), and some think excess insulin signalling through the IIRF links metabolic syndrome, obesity and cancer risk. Some bodybuilders take advantage of these hybridized pathways by injecting insulin to increase muscle growth.

        • Adrien

          “Some bodybuilders take advantage of these hybridized pathways by injecting insulin to increase muscle growth.”

          Yes and it can be very dangerous, some have ended in a wheelchair by simply trying.

          Listen from 7min to 8.

          Personally I used to eat dates after workout. And it worked fine.

  • skipstein

    I tried to post this on another topic but got it under the wrong caption
    to my question, so here goes. I am 67 year old make and was diagnosed
    with prostate cancer (Gleason=8) four years ago and immediately switched to a strict vegan nutritional base. I’ve been an avid fan of Nutrition Facts (post them on my Pinterest site daily). For the first time I had my IGF-1 level checked (my doctor didn’t have a clue as to why) after reading/hearing about the beneficial impact of a low IGF-1. Mine is now 105 (very low?) and my testosterone is over 800; just as the doctor’s video mentioned! But is it low enough to combat my prostate cancer (recent PSA=7 up from 5.8 4 months ago)). Most of my blood work is terrific (HDL=71 LDL-74, Triglycerides=38).

    It is really hard to develop targets for some of these tests and I
    want to better understand how I should proceed. Current literature is
    all over the place and none/few address prostate cancer and nutrition.

    Tell Dr. Greger thanks for his guidance.

    Skip Stein

  • 2378

    Just watched a doco on BBC on this, apparently all you need to do to half your IGF levels, is have 2 days a week where you eat only 1 meal for that day.

    Some people even go as far as every second day.

  • BETH


  • hulkimaniac

    Guess what!? Eventually youre gonna get old and freaking die regardless!!!!

  • Kelsey Byrne

    People – IGF-1 is also used for many other good things and growing is one of them. If you want to sit around on the couch and inject IGF-1 and think you’re going to grow then yes you’re probably going to grow a tumor. If you are working out and breaking your body down to build it up then IGF-1 becomes a way to recover and help with damaged areas. Also if you have a headache do you take an entire bottle of aspirin? Of course you don’t because you don’t want to die. The same should be said for anyone looking to take IGF-1. Like any drug prescribed from a doctor or supplement bought from a store research and education can help you safe guard yourself from ignorant mistakes. Again if you are breaking your body down seriously then IGF-1 helps in all sorts of great ways to shuttle nutrients to damaged areas. When it comes to cancer there are many variables but IGF-1 is obviously one link of a much larger chain and we shouldn’t demonize it just because one study shows it caused cancer. What about all the people smoking cigarettes or have extremely poor diets?