Doctor's Note

I introduced the tinker toy analogy in yesterday's video-of-the-dayProtein Intake and IGF-1 Production. I hope it makes sense! For those who haven't been following along, see IGF-1 as One-Stop Cancer Shop for the reason we're so concerned about IGF-1 levels and my videos The Answer to the Pritikin Puzzle and How Plant-Based to Lower IGF-1? to learn about the role diet can play. If the reason animal proteins raise IGF-1 levels is because of their resemblance to our own proteins, what about the few plant proteins that just coincidently happen to have amino acid ratios similar to human and other animal proteins such as soy? Great question! That's the subject of the next few videos starting with tomorrow's video-of-the-day Animalistic Plant Proteins.

For some context, please check out my associated blog posts: Animal Protein and the Cancer Promoter IGF-1 How Much Soy Is Too Much?, and Estrogenic Chemicals in Meat

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

  • Michael Greger M.D.

    I introduced the tinker toy analogy in yesterday’s video-of-the-day Protein Intake and IGF-1 Production. I hope it makes sense! For those who haven’t been following along, see IGF-1 as One-Stop Cancer Shop for the reason we’re so concerned about IGF-1 levels and my videos The Answer to the Pritikin Puzzle and How Plant-Based to Lower IGF-1? to learn about the role diet can play. If the reason animal proteins raise IGF-1 levels is because of their resemblance to our own proteins, what about the few plant proteins that just coincidently happen to have amino acid ratios similar to human and other animal proteins such as soy? Great question! That’s the subject of the next few videos starting with tomorrow’s video-of-the-day Animalistic Plant Proteins.

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

  • Freepam

    Your videos are getting better and better! That analogy is great and the little girl was perfect. Thanks so much for all this information.

    • PaddyCakes

      I failed to see the analogy of the girl, and it was confusing why she was placed there. I thought something was wrong with my computer.

  • ShellyB

    But don’t you get the equivalent of high quality animal protein by eating a variety of vegan proteins? Grains may lack lysine, but isn’t that shortage made up by eating legumes? And while legumes lack methionine, isn’t that shortage made up for by eating grains? That’s the theory I’ve been taught, called protein combining, that over a period of time such as one day or less, the variety of vegan proteins we eat are equivalent to the quality of animal proteins. Not so? What’s the explanation?

    • Thea

       ShellyB:  My understanding is that the idea of “protein combining” is a long debunked myth.  The best site I have seen for a detailed explanation of this issue is this:

      Hope you find that helpful.

      • Arnaud Clermonte

        Protein combining is not a myth.

        What this article says is that human non-athletes get enough protein from a vegetable diet without having to bother about combining.

        • Thea

           Arnaud: I’ve read your comment 4 times, and I just can’t figure out your point.  The article very clearly, and in agonizing detail, explains why whole plant food based eaters do not need to worry about protein combining.  After reading the whole page, the word “myth” seems quite appropriate.  What is your evidence for saying otherwise?

    • wendy

      I’m thinking it gets back to the ratios of the amino acids.  There are 20 amino acids required by the human body, 8 of them are essential which means you have to get them from food.  The other 12 can also come from food but can also be produced in the liver from one of the 8 essential amino acids.  If you are eating a meat based diet your liver probably doesn’t have to do much in terms of amino acid production, so our energy goes to cell growth.  If we were evolutionarily adapted to eat a more plant based diet then our liver is not being supplied the diet it was adapted for, so more IGF than our bodies need is being produced.
      One of the interesting things I read in the china study was relating to metabolic rate of people on a plant based diet being higher (more calories needed to maintain body weight than for meat based diets).  This could be a good explanation.  The liver energy requirements increase on a vegetarian diet because the liver needs to work harder, which can turn out apparently to be a good thing. 

    • Dr. Michael Lustgarten

      Grains do not lack lysine, that’s marketing propoganda. Here’s the analysis from my article…

      • Thea

         Nice!  Thanks for sharing.

      • Arnaud Clermonte

        That image doesn’t specify whether the lysine amounts are above or below the requirements.

        Also, you omitted wheat, which is the most consumed grain for your readers, and that makes your analysis very suspicious.

        • Thea

          re: “you omitted wheat, which is the most consumed grain for your readers, and that makes your analysis very suspicious.”

          This strikes me as a very odd comment.  I admit that I don’t know which readers you are talking about, but my daily grains rarely include wheat.  I have oatmeal for breakfast.  Lunches and dinners will usually involve some amount of whole rice, barley, corn, quinoa or farro.  I typically only get wheat if I’m eating a treat like a cookie.

          Based on recipes I see in cookbooks and on-line, I must be pretty typical for most whole plant food based eaters.  I wonder where you get your assertion?  Perhaps just an assumption?

      • ShellyB

         I still don’t get it.If grains are good sources of proteins, then why don’t they promote IGF-1 production just like meat does?

        • Thea

          If I understood Dr. Greger’s video correctly, he is saying that while plants can be *great* sources of protein (I hope you had a chance to check out that link I posted above), proteins in plants are not identical to the proteins in animals.  Human bodies react to the animal proteins differently than our bodies react to the plant ones.  This difference in reaction is to our benefit…

          Does that help?

          • ShellyB

             Clearly plant sources of foods produce different amounts of IGF-1 than do animal sources, so yes, clearly they are different for that reason. But I can’t see that their amino acid composition would be responsible for this because over a short period of time we consume similar ratios of amino acids from plant foods as we would if  we were omnivores, although the typical vegan doubtlessly consumes a smaller percentage of their calories in proteins. So, the difference in plant and animal-based foods must be either due to a lower percentage of protein, which might reduce IGF-1 production, or due to some accompanying factor in the food such as sterols in animal products vs. phytosterols in plants, which have a different chemical structure such as their extra ethyl group on their side-chain. Since sterols are animal growth factors and phytosterols and plant  growth factors which we, as animals don’t particularly respond to, I would think that the (animal) sterols would set us up for cancer simply by virtue of the fact that as growth factors, they would promote growth of tumors. But I can’t see how the argument that the ratio of amino acids is different can hold much validity- I don’t think the ratio is very different for vegans and omnivores when you take into account our natural protein combining behavior over a period of a few meals. Or as others have commented, the amount of varying amino acids in plants make the whole idea of incomplete proteins dubious. All this argues against complete proteins being responsible for cancer.

          • Thea

             ShellyB:  Thank you for clarifying your question.  I think I understand where you are coming from now.  It is a very interesting question.

            I definitely do not have the answer, but I think that the answer to your question lies in those few seconds where Dr. Greger went into medical talk and explained the process in “biochemical” terms.  I listened to that section several times and was not able to understand it.  I only picked up this: “…unlike essentials…precursers shunted into…oxidized into urea? and thus present less of a proto-something stimulus”. 

            I interpret this as meaning that there really is something to the idea that the ratio of various amino acids coming in makes a difference on how our bodies react to the proteins.  Just because you eventually get all of the amino acids that you need on a plant based diet does not necessarily mean that getting them all at once *in the same molecule* (assuming I understand this correctly) is a good thing or has the same effect on the liver.  In other words, as I understand it (which may be TOTALLY wrong), we may be talking about specific, separate amino acids, but they come into the body as linked together in “protein molecules”.  And it is how the body breaks down the entire animal protein molecule vs the plant protein molecules that makes the difference.  I could totally see how that could be true, though I understand why you are skeptical and really I’m just making it up.  I don’t understand it enough to have a valid opinion.

            I would love for a “bio-chem geek” to answer your question in as lay-terms as possible.  Anybody out there?

          • Thea

             ShellyB:  I have been doing more research and I think I actually got it right in my other posting. 

            Proteins are chains of amino acids. I had been thinking that a food like say a carrot or an egg would have a bunch of various amino acids in them, and hey, we call them proteins.  But no, those amino acids are actually linked together into molecules we call proteins. 

            The key is that proteins with different amounts of the various amino acids would have different molecule shapes (which is why Dr. Greger was talking about pyramids and cubes). 

            Thus, I believe what Dr. Greger is saying is that it turns out that the different shapes of the over all protein causes our body to behave differently.  The closer the shape of the protein is to our own body, the more our body creates IGF-1, because the protein is so easily absorbed? and doesn’t need to be broken down so much (it is so easy to build a pyramid).  But when the body gets a plant protein, the liver has to break it down into various amino acids in order to use them and this process means that IGF-1 is not created as much. 

            If animal proteins look very different from plant proteins, it would make sense that the process of breaking down the protein for use could have different results.  I still don’t know if I got it exactly right, but I have answered your question to my own satisfaction anyway.  ;-)

          • Toxins

            The protein structures and ratios determine how our liver recognizes and treats the protein. If one eats a protein that closely resembles the protein structure of our own cells, then our liverr will release IGF-1. IF it is plant protein our liver treats the protein differently as the protein must be assembled.

          • bob

            As a would be life extentionist I see the never ending conflict between the calorie restriction advocates and others who tend to want to encourage a higher metabolic rate/boosted immune system or similar. Some supplements such as resveratrol are supposed to be calorie restriction mimics. I currently take colustrum (IGF-1?) as a supplement…supposed to boost the immune system. Also eat some animal protein (minimal) and intend to take some targeted amino acids (argine/ornithine). I’m currently walking the tightrope between life and death (as we all are…though younger people don’t know it yet?)…over 65 and trying to avoid sarcopenia. Probably not much point in being alive if you can’t get about…though some people manage things this way.
            As some say…you makes your choices and you takes your chances?

        • beccadoggie10

          IGF-1 stands for Insulin Growth Factor-1. Proteins in plants like grains are not the same as proteins in animals. And, the human body reacts to plants differently than it does to animals.
          IGF-1 first came to my attention, when Dr. Samuel Epstein and others studied recombinant bovine growth hormones which were injected into cows to force them to produce more milk. (Milk obviously is from animals). Here the IGF-1 factor induced breast cancer in human women, prostate cancer in human men, and colon cancer in both sexes.
          The IGF-1 factor, in this case is what pushed many consumers to only seek out certified organic milk, which disallows genetically engineered organisms, hormones, antibiotics and much more under the law.

    • Toxins

      Grains do not lack lysine and beans do not lack methionine as shown here in the USDA nutritional database.

  • Patrickdube

    Probably one of your best simplification job ever of a complex situation. Bravo!

  • Thea

    I totally agree.  This is an awesome explanation.

  • Kat

    That sounds right on, but what about this that I just read?

  • Chocolate KenDoll

    What about “complete” plant proteins, like soy or quinoa? Any research on how they stimulate the liver? Also, I’ve heared that tofu was a complete protein but “low in quality” but that’s probably incorrect, right? Tofu is complete (however, misleading that labeling is) and high protien right? 

    • Toxins

      All whole plant foods are complete proteins, for whatever reason the media has labeled quinoa as “special” for being complete when all whole plant foods indeed are. The difference is that the ratios and protein structures are different and soy happens to resemble a very similair ratio to animal proteins.

      • Dan Lundeen

        Hemp protein is globular (immune proteins), whereas soy is closer to muscle amino acid profile – wonder if the hemp would be similar to soy in IGF-1 generation?

  • Michelle Blaxall

    Love the cubes and pyramids analogy.  Thank you Dr Greger for “breaking it down” for us.  I think a similar metaphor could be applied to the whole debate around estrogens vs phyto-estrogens in milk vs soy milk.   The son of a friend of mine was recently advised by his coach to switch from soy to cow’s milk to avoid those scary phyto-estrogens.  Wha?!

  • Jane

    I am new to this way of eating and your videos, most of which I really enjoy and have learned a great deal, but this one confused me.

  • Agil

    O.K got the IGF-1 issue but i heard that animal protein is also related to making uric acid in the blood, somebody knows anything about that ?

    • Dan Lundeen

      Yes, purines in protein and fructose in sugar increase uric acid levels. A lower protein level as found in a plant-based diet and cutting back on refined sugar/honey/agave syrup/etc. may lower urate levels.

  • info on soy products please

    what about too much soy…..information please

  • Mmmeat

    If gelatine is not a complete protein- then does it follow that jelly / jello is ok?

  • Billy

    I LoL’d when you said, “Without a doubt the highest quality protein on the planet for us is human flesh.” :)

  • diane

    I take a med that comes in a gelatin capsule. Is this a significant source of animal products? I can change to a tablet but then it isn’t slow release and I have to take it several times a day, which means I’d forget more often.

    • Tania

      My question is similar. But it seems no one has answered you. I consume a 100% plant based diet and my new naturopath wants me to take a supplement that has gelatin in it. Typically I would refuse, but thought it would be good to get some opinions on this. I did a search for gelatin on this site and only found the above video. Am I making a big deal to refuse the supplement because it contains gelatin or is there some good reason to refuse it…such as risk for acquiring Mad Cow or something? Would love to hear from someone.

  • shiftpolitics

    Hello Dr. Greger.

    Do all plant sources from vegetables to beans have all the amino acids necessary in them? or do we have to combine grain with beans to get all of the amino acids like Frances Moore Lappe I think postulates?

    Another question, I know you’re not exactly on the same boat with raw veganism but, what is your take on the 80/10/10 diet? (since colin t. campbell has came out lately publicly supporting it)

    Grateful for your work :)

    • Thea

      shiftpolitics: I’m not Dr. Greger, but I think this site is very well researched and answers your questions about protein. It answers just about anything anyone would ever need to know about protein:

      Good luck.

      • shiftpolitics

        welp, i guess wikipedia is sufficient.

        • Thea

          :-) Yes, I’ve seen that before. I like the site I shared with you a bit better since I think it is more complete. But yes, Wikipedia is short and to the point. :-)

  • bob

    Cancer Condos. That conjures up a whole futuristic world.

  • Antler Farms

    Raise IGF-1 naturally by taking deer antler velvet.