Doctor's Note

For background on the cancer-promoting effects on IGF-1, be sure to check out IGF-1 as One-Stop Cancer Shop. Next, I’ll unveil The Answer to the Pritikin Puzzle, for those who missed the spoiler alert in Uprooting the Leading Causes of Death. What puzzle? See Ex Vivo Cancer Proliferation Bioassay and Prostate vs. a Plant-Based Diet.

For more context, check out my associated blog posts:  Eating To Extend Our LifespanHow Do Plant-Based Diets Fight Cancer? and Why Are Children Starting Puberty Earlier?

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  • For background on the cancer promoting effects on IGF-1 make sure to check out yesterday’s video-of-the-day IGF-1 as One-Stop Cancer Shop. Tomorrow I unveil The Answer to the Pritikin Puzzle, for those who missed the spoiler alert in Uprooting the Leading Causes of Death. What puzzle? See Developing an Ex Vivo Cancer Proliferation Bioassay and Prostate Versus a Plant-Based Diet.

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

  • Elpoo

    It’s not working! How will I ever learn how to live forever! Oh, the humanity!!!

    •  Sorry Elpoo–we’re working on it. Stay tuned!

      • Valnaples

        LOL…yes, what’s the “dietary manipulation” needed???

        • Didi Nour

          Yes plz! where to find the “dietary manipulation” info.??? and what kind of veggies that promotes IGF-1?

      • Han

        But don’t hold your breath. ;-)

  • BPCveg

    Interesting sentence (from the Discussion section, paragraph 2) of the source article (Guevara-Aguirre et al.):

    “The lack of lifespan extension in GHRD subjects may be explained in large part by the major proportion of deaths (70%) caused by convulsive disorders, alcohol toxicity, accidents, liver cirrhosis and other non-age-related causes.”

    GHRD refers to the Growth Hormone Receptor Deficiency subjects who were the experimental group in the study that Dr. Greger is describing. They are not just deficient in IGF-1, but also growth hormone receptor (GHR).

    •  BPCveg always with the sharp eye.

      • BPCveg

        Thank you sir!

    • Doug R

       About 24 seconds into the video, Dr. Greger reports that these little folks have an insignificant amount of  the hormone itself, especially compared to their relatives, not just defective receptors- which they also have. But why do you suppose these folks die from convulsive disorders so often? I noticed that they live in Ecuador;  where cocaine is easily available. Could it be that their little bodies can’t handle cocaine as well- if that’s the cause? I think that having smaller livers must be what explains their alcohol toxicity.

      • BPCveg

        Doug R: I have the impression that the convulsive disorders are referring to epileptic seizures. 

        There is evidence of a connection between epilepsy and reduced growth hormone and IGF-1 levels. For example, see:

        • Doug R

           Thanks BPCveg, it could be, but I’m not sure this article is saying that. Seems to me it’s blaming the treatment drug,  ‘post provocation’  valproate for reducing HGH and IGF-1, instead of saying that epilepsy and low IGF-1 are commodities. ‘Course, I could be reading it wrong and it is interesting that the treatment group had higher BMI’s, something common with the little guys who have Laron’s. If you find anything more specific, please let us all know. I’m sure you’re much more informed about this stuff than I am. I just thought that if they’re inclined in their culture to drink to excess, resulting in death, the same could easily be true of cocaine misuse, which can cause convulsive disorders. I also want everyone to understand that I don’t want to appear to be critical of the little guys; if I am, I’m afraid that they may come and bite my kneecap.

          • BPCveg

            Hi Doug:  Sorry for sending the wrong article; I agree it doesn’t quite convey what I tried to suggest.

            I did a few more searches on the subject (wikipedia, google scholar, etc) and it turns out that those who suffer from Laron Syndrome (the type of dwarfism described in this video) frequently have chronic low blood sugar levels (hypoglycemia) and that this low blood sugar can lead to shortage of brain blood sugar (Neuroglycopenia), which is associated with loss of conciousness, damage to the brain, seizures etc. I guess that this may explain why those with Laron’s syndrome suffer from more “convulsive disorders” and more accidents. What do you think?

          • Youcef

            Interesting. Can low IGF-1 and/or high hgh (because that’s the case for Larons) be linked to chronic low blood sugar? And if so, what is the mechanism?

  • Barry

    No diabetes either.

  • nm

  • Mike S

    I hate the cliffhangers, lol!   I just wanted to say thank you.  I love this site and the scientific approach you take toward nutrition.  

  • Rainbowocean

    I would like to know the average life span of these people.I remember learning that people with Drawfism live a shorter time.  If you live a signifaclly shorted time you have less time for the cancer in your body to grow.

  • Ryan

    Blaming IGF-1 for cancer sounds legitimate, but how can you explain people like Steve Jobs, who are lifelong vegans, getting and dying from cancer? His own body produced too much?  I read Dr. McDougall’s article on Steve Jobs, but the issue of why cancer was able to thrive in his body despite his vegan diet was never fully addressed.

    • Carl

      Jobs was overweight for some time. Who knows what he ate behind closed doors exactly? I’d say processed foods helped to keep him that way and could also have negative effects.

      • Ryan

        That’s a possibility.  Though he abstained from eating animal products, he may have eaten a lot of fried and processed foods;  that’s a big ‘maybe’ though.  Even with that being said, Dr. Greger is saying that people switching to a vegan diet maintain lower levels of IGF-1 and produce blood that is “inhospitable to cancer.”  Even if he was exposed to high levels of carcinogens, cancer shouldn’t have been able to thrive in his body as it did.  That’s the part that I find troubling.

    • Mike Quinoa

      I think with Steve Jobs it was more a case of exposure to carcinogenic substances early in his career, and less related to excess IGF-1. I read Dr. McDougall’s excellent article as well. Heavy-duty chemical carcinogens may have, unfortunately in this case, trumped Steve’s veganism. 

    • Maureen

      As Mike and Carl point out, there are lots of factors in life besides diet that contribute to risk, though diet is certainly one of the most important ones.  You can also always find exceptions to rules, like the guy who smokes two packs a day and drinks like a fish but lives to be 104.  It is extremely uncommon, but it happens.  Likewise, you can find the person who does everything right and still gets a horrible disease.  But statistically speaking, those examples are so rare as to be relatively insignificant – they don’t prove much of anything.  What is much more common is for people who take good care of themselves to live longer, healthier, more functional lives in general, and for those who don’t take care of themselves to run into debilitating problems prematurely, or death.  It’s not 0% vs. 100% probability, it’s always somewhere in between.  All we can do is just work to improve our chances, even though there are never guarantees.

      •  Right on Maureen. Anecdotes are interesting, but statistical significance is what matters.

    • Steve Jobs was not vegan – he ate fish!

      • Mike Quinoa

        I think Steve was in fact vegan, up until his pancreatic issues. Then he encountered, and ultimately gave into, pressure from his wife and his docs to include animal protein (e.g. fish) in his diet.

      • Ryan

        From what I understand, he only began eating fish near the end of his life.  The cancer grew slowly over the course of a couple decades, during which time, he was vegan.  At least that’s what I’ve read.

    • Toxins

      Who knows what his vegan diet consisted of. Perhaps he included many refined products, or perhaps he exposed his body to many carcinogens. There are a number of possible nutritional factors. “Vegan” only means no animal products. Oreos, chips and white bread is all vegan.

    • Youcef

      A vegan diet does not mean zero chance of cancer, only a reduced chance of cancer.

      • Toxins

        A vegan does not equate to health either. White breads, candy, french fries, mock meats and the like are all vegan yet considered unhealthy foods. Ideally we want to consume whole, unrefined plant foods.

        • Youcef

          Precisely, “vegan diet” is a concept, it’s execution in practice is what makes the difference. Even farm fresh organic veggies could have heavy metals like arsenic, a potent carcinogen especially common is the Australian and New Zealand soil. Cooking methods matter, Dr Greger pointed that raw vegan diets are more susceptible to vitamin and mineral deficiencies, cooking method also matter (i.e. frying is vegan), burnt food (i.e. burnt carrots) is carcinogenic…

  • BPCveg

    Here’s a link to a Scientific American article (published Feb 2011) covering Laron’s syndrome (the type of dwarfism discussed in this video):

    The article makes essentially the same argument as Dr. Greger – first noting that those with Laron’s have virtually zero cancer rate and then noting that “greater protein intake and higher IGF1 levels contribute to the increasing cancer incidence”.

    Astonishingly, near the end of the article quotes one of the researchers stating:

    “people shouldn’t make up their own diets to try to extend their life. If you don’t have a clear disclaimer, you will be amazed at what people do.”

  • Rafa

    A plant-based diet can lower IGF-1 levels, but how do the lower levels post diet/exercise compare to people with Laron’s syndrome or people in the lower risk group in the meta-analyses shown in the video?

    • Rafa

      Sorry I was referring to the meta-analyses shown in the previous video.