Doctor's Note

A few videos on raw foods diets:

And how do raw vegetables rate against cooked vegetables?

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  • Veguyan

    I heard that the lycopene boost from raw tomatoes in a Vitamix is just as potent as the lycopene boost from a cooked tomato sauce. I heard this from a Raw Fooder.

    What do you say?

    • Michael Greger M.D.

      I’m afraid your raw fooder friend may have been misinformed. As you can see here, the heating itself seems to improve the bioavailability of lycopene. I would not be surprised if the blending helped too, though, so you could blend and heat and have the best of both worlds :)

      • LynnCS

        Going to have to get my lycopene somewhere else. Hate warm/heated/cooked tomatoes. I have always loved vegis right out of the garden, so raw suits my taste. I think if you eat a variety of vegis, you’re probably not going to get enough of one thing like goitrogens to make a difference. But I do like broccoli and other cabbage relatives slightly steamed. Mostly I like them cooled and put in my salads. Try cold cooked Brussels Sprouts in a great salad that includes salty olives and sweet raisins with a dressing of orange squeezins and a dash of lemon. I do love my raw food, but include some steamed. No point in being so rigid about it. I would like to see the studies though. Many people on both sides of the issue don’t back it up with studies. I appreciate your research, Dr. Greger.

    • But Lycopene isn’t the whole world.

      As far as I know there are about 10.000 different chemicals in tomatoes.
      What happen to all these when we cook them?
      A lot of it is probably destroyed.

      • albert

        Valid point, I guess. Why not to eat some of them cooked and some raw, right? :) I do love tomatoes in any edible form – can’t wait for a summer to enjoy everything naturally grown and ripe..

  • myjolina

    Fact or Fiction? raw foodists insist on sprouting all their seeds and nuts for the best digestive consumption. Is it really necessary? If I don’t sprout my sesame seeds before I add them to my kale chips am I really losing out?? If I grind my flax seeds vs. sprouting them – is there really a difference in the way they are metabolized in my body?

    Do you have a whole list, other than those mentioned here, of veggies that are better for us when cooked?

    • DStack

      As I understand it, soaking releases the enzyme inhibitors in the nuts and seeds, rendering them more easily digested. It can also activate and increase nutrients in the seeds as they prepare to germinate. I soak now for this reason. With flax, it’s easy to soak overnight and then blend. It’s difficult to truly sprout flax without any dirt, as they are mucilaginous. By soaking and blending, you get the best of both worlds.

    • Bat Marty

      not all raw foodist eat italian raw food group on facebook suggests not to eat sprouts..

  • Toxins

    I am curious to know myjolina’s question as well. I always here about lycopene but thats just one single anti oxidant. What else is benefited nutrition wise from cooked food vs raw food.

  • Jennifer C.

    I agree with the above posts. A review of the foods that are better eaten raw would be a great idea for another video on (Hint, hint!) :-)
    There are two videos already posted on cooking methods and nutrient absorption: and
    It is my understanding that a mixed raw and cooked approach is best. Cooking certain foods can increase their nutrient content, and in addition, help to decrease “anti-nutrients” (that bind to essential minerals) and inactivate certain substances that may be problematic if consumed in high amounts (like goitrogens). For example, cooking may help inactivate the goitrogenic compounds in broccoli. Soaking and boiling beans, leavening grains, and heating tomatoes are other good examples of traditional cooking techniques that may be beneficial. On the other hand, fruits and nuts (like pineapples, avocados, and almonds) are generally considered healthier in their raw state.

  • Jubilee

    I stumbled across the
    so called 80 10 10 diet on

    Can you tell me if this diet is great and healthy? Or do people following it risk malnutrition?

    • A diet of 80% carbohydrates, 10% protein, and 10% fat sounds pretty close to the McDougall diet but the devil is in the details. What type of carbohydrates… mainly starches aka chains of glucose molecules.. would be very good. What type of fats are we talking about. Protein 10% what is the source of the protein. So it is not about relative amounts and percentages. You might enjoy some of the free video’s on the McDougall website. I would recommend you start with The Starch Solution…. look under education>video’s>free e lectures.

      • DStack

        80/10/10 seems to be essentially the same as McDougall’s approach except that fruit is the focus instead of root vegetables and grains. While sweet potatoes are certainly healthy, couldn’t it be argued that the fruit is much more nutrient-dense and allows for a more varied diet than McDougall prescribes? Fats as I understand aren’t deliberately sought out, save for maybe a handful of soaked raw nuts or seeds. Protein is essentially the same, you get what you need from the fruit and nuts, you don’t seek out a specific concentrated source. I’m considering shifting to a “raw before 4” kind of approach, so that I can get the benefits of a high-fruit diet and then load up on steamed veg and sweet potatoes at the end of the day. Best of both worlds?

        • Bat Marty

          Mc Dougall suggests to eat starches, and not fruit, I think because 1) it’s more backed by science (not so many researches on raw foodist) 2) it’s cheaper and easier to eat starches than all raw fruit so more people can embark on a starch diet and follow it, in fact he said (in a 2004 conference – see here I translated it for my italian friends, but the video is in english – see at the minute 24) at one point of the conference that the suggested portions of fruit and vegetables have been raised to 9 a day and “pretty soon they will tell you something pretty radical that is to eat just fruit and veggetables because that’s what the truth is”.

    • Andrea

      Dr. G addresses this at 2:25 in the video when he says a diet based on fruits is NOT nutritionally adequate and would need to be supplemented with a daily consumption of 5-10 cups of dark green leafy vegetables and a half a cup of nuts or seeds.

  • GeorgeI


    The vegan community is overrun with even intelligent people promoting raw foodism, simply on the force of personality rather than actually reading anything about the validity of the beliefs.

    It has gotten so bad I just keep my mouth shut about it so I don’t end up friendless.

    This video is going on my blog and my Facebook page.

  • JamesKB

    Modern fruits a pale shadow of the fruits we used to eat. Where does this come from? What do they lack?

    • Toxins

      Fruits have actually become more nutritious and hardier due to domestic “breeding”. Greens on the other hand have been grown to be less bitter and this bitterness accounts for very powerful phytonutrients which are now in lesser amounts.

      • JamesKB

        I’m after references

        • Toxins

          It is in one of Dr. Greger’s videos, I forget which one exactly.

  • This video is available with Portuguese subtitles at my blog’s youtube channel:
    Este vídeo está disponível com legendas em português no canal do meu blog no youtube:

    Ana C Vestergaard

    • Michael Greger M.D.

       Eu realmente aprecio sua ajuda difundir esta informação para salvar vidas

      • Hi Michael, what is your opinion on the 80/10/10 diet? As another viewer asked above previously? thanks!

  • popo911

    In a later video you say that it is a myth that produce today lost most of their nutrients, and lose less than 20% on average. But in this video you say you cannot base your diet on fruits because they are a “pale shadow” of what they should be. It sounds like an inconsistency to me. A fruit based diet is perhaps the only sustainable raw diet because a nut staple has too much fat and not enough carbohydrate, and a leaf staple simply don’t have the calories. I know I did well for years on a fruit based diet (yes with b12 sup). Fruit is a wonderful alternative to the beans/whole grains staple paradigm in vegan diets.

    • herbalist

      If one was to go on a literal “fruit diet” I agree that it is lacking in nutrients. Some examples include but are not limited to; b vitamins, omega 3 oils, protein etc.

      Though if one was to go on a botanical description of a fruit diet that included avacados, nuts, tomatoes, cucumbers, etc that would be more nutritious.

      Though I still believe that both diets would be nutrient deficent.

       Some examples of nutrients would be b vitamins,and sustained energy sources(whole grains cause a slow rise in blood sugar that plateaus and is sustained over 4-5 hours vs many small meals of fruit). Many small meals in comparison to whole grains spike up blood sugar levels quickly then drop quickly(similar to sucrose, but not as quickly) which in turn puts an extra burden on the pancreas. This extra burden wears out the pancreas over time.

          Not to mention digestion problems as many small meals interfere with proper digestion time. Thus as a result, transatory time is off set which then leads to putrefaction. Putrefaction, in the large and small intestines then leads to cancer, IBS, altered ph balance, etc

       Furthermore, there are various methods(3) that the body uses to convert foods into sugar that the human body runs on. The most efficent conversion system that the human body utilizes is based on starches. Thus elimination of the most efficent energy source of conversion does have side effects. Some side effects are catabolism of muscles, increased alternate energy pathway by-products such as amonia etc. These by products wear out the bodys organs at an increased rate.

      Thus total elimination of grains, or eating a diet of fruit will have its problems….Thus in my opinion a reduced diet of grains makes more sense.

                                                fats                        10 *
                                              protein                      20
                                         whole grains                   30
                          fruit-vegetables 60 raw- 40 cooked   50

      *  Figures may vary somewhat +/- 5-10% depending on body type metabolism activity levels etc.

      • DStack

        Thanks for the thoughtful reply. As I understand it, the 80/10/10 people argue that the grains are not as nutrient rich as fruit, but are equally calorie-dense. I’m all for balancing things out, and I’m interested in what you’re saying about many small meals, however I think the fruititarian philosophy also makes sense and the people doing that seem to be getting great results. I’m considering a “raw before 4” plan so that I get the benefits of a high-fruit diet with some cooked veg and some whole grains as well. I was going to aim for less than 30% grains, though. Maybe more like 10% or 20%. Thoughts?

        • mikeysbro

          I definitely think 10% is too low since I tried it for awhile. What I found was a couple of things, it seemed to me that I was sore and irritated (temperament).

          Thus, I found when I increased my grain intake not only did I sleep better (something to do with tryptophan crossing into the brain ie gluten is protein and could be a good reason why 80/10/10 people mention that they believe they need less sleep since it is not crossing into the brain though exercise can do the same thing as grain) I had more patience (likely from increased b vitamin intake and sugar stabilisation levels due to chromium, fiber etc ) and experienced decreased soreness after work outs and work.

          Fruit contains certain nutrients ie antioxidants, various vitamins a,c etc but grains contain other nutrients that help regulate homeostasis such as chromium, b vitamins, and whole grain starches that are converted slowly over time sustaining energy levels and not spiking up blood sugar levels (compared to fruit) quickly then dropping it. Also wheat bran is essential for creating the proper environment for bacterial growth (reference is on this site) including that it cleans the intestinal tract somewhat differently that indigestible cellulose found in fruits.

          Therefore in my opinion both are useful though depending on ones activity levels and health goals one may increase performance over the other.

          The people extolling more of a fruit diet tend to be runners that are trying to eliminate almost all fat. (even though some fat is a good thing estrogen is produced by fat). Thus they drop most grains as a way to dump this fat but are eating more often and using other energy production pathways that are inferior because of the by products produced which put additional burdens on various organs.

          Though both have their place and its obvious that too many grains cause obesity and are devoid of antioxidant activity that fruits contain. Therefore I believe a diet consisting of 40% + grains is way too high especially since modern lifestyles are very sedentary and we do not require that converted energy all day.

          In addition, I have a friend who is on the 80/10/10 he swears by it but I noticed that he too is very irritable even though he supplements with lots of nutritional yeast. In fact he is more irritable than when he ate more grains and supplemented compared to the way he is now. He blames it on his blood sugar being low which is true it is low but its because the decreased amount of grains and the increased requirement to keep blood sugar levels up (he eats 4 meals a day, though I eat 3) by eating more often.

          Therefore 10% is too low and 40% is too high. I would suggest a happy medium between the two 40-10=30/2=15 10+15=25% as a great place to start. ;)

      • Bat Marty

        if you use you can see that a raw food diet (with the proportion of 80-10-10, that is also a percentage Colin Campbell agrees upon) lack basically only in B12 although many people appear not to be deficient after years of raw food, even if they do not supplement (see fully raw Kristina, on you tube, but I know others, not famous ones) proteins you get them from green leafy vegetables, if you eat enough, 80-10-10 raw foodist eat even 1 kg of green leafy vegetables a day, so no lacks there. Roaw foodism is just more expensive to follow, because fruit is much more expensive than many move to the equator..ciao

  • Thank you or creating this video. Staying on top the published data is critical.

  • Toni

    Where can I find scientific proof that plant enzymes are deactivated by our stomach acid? I want to show it to a raw fooder who’s teaching everyone that if we don’t eat everything raw we won’t get enough enzymes and our body has to use it’s own enzymes and they won’t last for long. Eventually all the body’s enzymes have been used and we’ll get sick and die…

  • danka

    I would like to ask whether it is appropriate to include the food combination chart – food is sorted according digestion.

    And if it is really necessary to eat fruit only on an empty stomach and just by it self … or else can ferment

    Thank you very much

  • Few people know that humans cannot use enzymes from plants or any other species of plant or animal. Enzymes are specific to a single function and work in concert with other enzymes in individuals that synthesize the enzymes. Read Whole: Rethinking the Science of Nutrition by T. Colin Campbell for details.

    • I would agree. In addition enzymes are complex molecules usually protein which are digested and are not absorbed into our bodies. Enzymes also often function as catalysts. The are therefore used over and over again.

  • David Fernandez

    I’ve received lots of ‘facts’ from a person eating 100% raw MEAT and veggies.. assuming is the best nutrients, energy, enzymes, not poison substances when cooked etc etc.. she just didn’t want to understand why raw or cooked meat are bad for her at the end.. how can i show her with facts that she is wrong and she could put in danger her health? please :)

    • People change at different rates. Certain folks are not open to changing their belief systems. In dealing with patients I would start by exposing her to information that relates to disorders which she is concerned about. I would ask her for the studies she is providing. Most of my patients are getting there “data” from sources that aren’t based on the best science and usually have commercial interests. Younger patients tend to be less concerned with disease then as they get older. You could point him or her to specific video’s on this website in areas of interest. If they are willing to invest that much time into looking at the science you probably won’t be able to change their beliefs and then their behavior.

    • Jen Drost, Physician Assi

      Hi David :)) Check out Dr. Greger’s video on exactly what you just stated
      Good luck! You are doing a great job being a positive model for your friend :))

    • Toxins

      The 3 videos on endotoxemia and the several on IGF-1 I think are the most compelling.

  • Jon

    you are idolizing lycopene like meat eaters idolize lycopene

  • Jon

    you are idolizing lycopene like meat eaters idolize protein

  • Ellie D

    Dr. Greger, why do you think that there are 60-80 year old raw foodists out there that look like they are in their 30s? Do you think they are just exceptions and would have looked like that on a cooked food vegan diet too? Do you think eating raw had anything to do with it?

  • Ilana

    Can you address specific diets like the 80/10/10 or the specific carbohydrate diet?

  • Gabrielle

    I know you have some videos up about specific foods that should not be eaten raw like mushrooms and beans.Can you make a video of (vegan,obviously) foods that are better raw, better cooked and foods that are just as good either way? Foods that should never be eaten raw and foods that should never be eaten cooked? Also maybe popular vegan foods that should be avoided? That would be cool.

  • curious

    Raw versus cooked vegetables and cancer risk.

  • Sallie

    Dear Dr. Greger, At some point I saw one of your older Year-in-Review speeches on Youtube. In it you showed data indicating vegetarians die from Alsheimers at a greater rate than meat eaters. I can’t find a video here about it. Do you still stand by what I thought I understood at the time?

    • Brenda Amira

      I know this is a year old, but I’m not sure if you ever got an answer. I think I know the video you are speaking about. I watched it several times. The information was invaluable. It was not a year in review, but it is on YouTube. Search “forty year old vegan dies”
      I think it’s of heart attack but that’s enough to find the right lecture. Very, very informative.

  • Dustin Tapp

    Stomach capacity? We didnt evolve on cooked foods. I know extensive amounts of raw children who eat primarily fruit based diets that have never touched a b12 supplement. By what age would you expect a child to show cognitive issues if you believe this to be an issue? Many of the children are over 8 years old and free of any issues

    • Penny

      Okay, well first we need to know what is meant by primarily fruit-based diet. Children who are eating completely animal-free are definitely at risk of B12 deficiency. There are several stages, and how and when the deficiency becomes obvious can vary, however it is irresponsible not to be ensuring some source of B12.
      The deficiency and its consequences are well-known no matter what side of the nutritional debate you are on. Unless these extensive amounts of raw children are yours or are patients of yours, you have no way of confirming that these children are, in fact, free of any issues or that they are not getting B12 from some source.

    • JacquieRN

      You may want to check here for B12 recommendations for infants and children:

  • Tobias Brown

    I’m so glad this video is in the archive. It so tiresome to listen to raw foodist who insist raw is the only way to health. They are so wrong.

  • We consider a LOT of ‘raw’ food recipes to be processed foods. Water is removed from the items, the items are blended fine or ground fine, processed oils are added, salt and sweeteners are added. Often they do not look any healthier than junk food.

  • Doc Suzy

    Years ago my mother had breast cancer. They did a biopsy and she woke up without a breast. Five years later it showed up somewhere else. She never shared where that was but I do know it was much more serious. They told her that if she did not do what they prescribed she might live 6 months if she was lucky. She walked away from their recommendations for treatment and went on a raw food vegetable based diet with LOTS of fresh vegetable juice for the first year. Needless to say, she outlived all of her doctors! Food has remarkable healing powers.

  • Sharon

    Aren’t B12 supplements recommended for everyone on a plant based diet, whether raw or not? The video seems to imply that B12 supplementation is needed only if you eat raw foods (exclusively).

    • dogulas

      He was just saying what raw food people absolutely need to know to not get sick. B12 needs to be supplemented for any plant-based diet. And probably the omnivore diets too.

  • Jerry Razee

    Why do cooked veggies have more vitamin B12 than raw veggies?

    • dogulas

      They don’t. In fact the B12 even on unwashed veggies is negligible. B12 needs to be supplemented in both cases.

      • FARIDY

        Vegetables or any other type of food DOES NOT have vitamin B12.Vitamin B12 is manufactured by a bacteria in our digestive tract (intrinsic factor) and it is found in the soil where organic dense nutrient soil grow. It depends on the individual, if his/her lab tests show B12 deficiency, then a supplement would be necessary. When I was a meat eater 4 years ago, I was a vitamin B12 deficient, iron deficient (anemia) and low calcium. Now that I am 100% vegan, I DO NOT TAKE ANY SUPPLEMENTS of any kind, all my lab tests show normal and healthy. By the way, B12 deficiency is not only a problem found in Vegans, meat eaters have the same problem.

        • dogulas

          So you rely on unwashed vegetables etc for your B12? If that is working for you, more power to you. B12 supplements have not shown to have any harm. Nor D supplements for those of us who live too far from the equator and have long dark winters. Best of success to you.

  • Kaitlin

    Hi Dr. Greger!

    I just wanted to let you know that I absolutely love your videos! I love how you always cite you sources! I had been reading about raw food diets quite a bit and I was intrigued, but skeptical, about the health claims. Thanks to you, I feel like I can make an informed decision about my diet. I’ll keep eating vegan with an emphasis on raw greens and veggies but there’s no way I’m giving up my cooked beans!

    Thanks for the awesome videos,


    The only strong and reliable evidence there is on this is how the person feels, no comparison. May not be scientifically proven, rather empirical, but there are many personal testimonials that attest the complete reversal of serious conditions, how people feel, full of energy and no deficiencies and no need to take supplements, according to the lab tests.
    This is a controversial topic, although I do agree that certain foods cooked or steamed could be more absorbable for the body, such as carrots, tomatoes (more lycopene) and broccoli, for example.
    Also, I do not understand the possibility of lack of vitamin B12 with rawfoodists, and they may need to take B12 supplement?, if they are consuming veggies, raw, specially organic and out of the soil, a dense nutrient soil that precisely is rich in B12, since a bacteria is responsible of manufacturing B12. B12 is in the soil, how could be deficient? I grow my own vegetables and eat them raw and my lab tests show levels of vitamin B12 normal and I do not take supplements.
    We are part of Nature and animals in Nature do not cook their food. Raw food is the most natural way to ingest nutrition, there is no other way, since the cooking process destroys some nutrients, no question about this!


    The only strong and reliable evidence there is on this is how the person
    feels, no comparison. May not be scientifically proven, rather
    empirical, but there are many personal testimonials that attest the
    complete reversal of serious conditions, how people feel, full of energy
    and no deficiencies and no need to take supplements, according to the
    lab tests.
    This is a controversial topic, although I do agree that
    certain foods cooked or steamed could be more absorbable for the body,
    such as carrots, tomatoes (more lycopene) and broccoli, for example.
    I do not understand the possibility of lack of vitamin B12 with
    rawfoodists, and they may need to take B12 supplement?, if they are
    consuming veggies, raw, specially organic and out of the soil, a dense
    nutrient soil that precisely is rich in B12, since a bacteria is
    responsible of manufacturing B12. B12 is in the soil, how could be
    deficient? I grow my own vegetables and eat them raw and my lab tests
    show levels of vitamin B12 normal and I do not take supplements.
    are part of Nature and animals in Nature do not cook their food. Raw
    food is the most natural way to ingest nutrition, there is no other way,
    since the cooking process destroys some nutrients, no question about

  • Health Glows

    But…. is more better?

    And about the enzymes. Yes, it is a myth that plant enzymes aid our digestive enzymes, but isn’t it truth that plant enzymes intact serve actually to decompose food in the cardiac stomach.

  • BB

    Have you considered that other animals don’t cook their food and they are doing just fine? We are the only life form on earth that cooks food? Have you considered that increasing the bioavailability of nutrients like lycopene through cooking may not be healthy? A slow release might be better and more balanced? We already know that too much of certain nutrients causes disease… like too much protein. How do we know that the more lycopene through cooking is better?

  • Bat Marty

    I watched the video and I wonder, how did men evolve 12 million years ago without cooking his food? children had a small stomach too, then..I read that cooking food came later..more recently, so how could they once strive on raw food? thank you

    • Tom Goff

      I think your timescale is wrong – modern humans are much more recent than that. And our pre-human ancestors were thought to be using fire long before homo sapiens came on to the scene. There is of course a well-known theory that it is cooking that allowed the emergence of homo sap.

      • Bat Marty

        Hi Tom, thank you for your reply :-) I will check your links, I don’t know where I got the 12 millions figure..I forgot. Still doesn’t this reasoning holds? If they evolved without fire – and that came later than the time man appeared on earth- doesn’t that mean that nature hadn’t thought that they (we) should cook?…

        • Tom Goff

          Nature doesn’t plan or design anything. Stuff happens,

          In any case, humans evolved after our non-human ancestors had already been using fire for a long time. In fact, the theory is that without fire and cooking there would be no human beings because cooking is actually what made us human.

          But isn’t your argument the same as that used by people who said that travelling in a motor car or an aeroplane is unnatural and wrong because nature because nature didn’t design us to travel that fast or to fly?

          Finally, the sort of argument that was in your first post is what is called the “appeal to nature” fallacy ……….
          “An appeal to nature is an argument or rhetorical tactic in which it is proposed that “a thing is good because it is ‘natural’, or bad because it is ‘unnatural'”.[1] It is usually an invalid argument, because the implicit (unstated) primary premise “What is natural is good” typically is irrelevant, having no cogent meaning in practice, or is an opinion instead of a fact.”

  • Julia Drake

    I often hear people in the raw food community claim that soaking raw
    nuts or seeds overnight removes enzyme inhibitors, making them easier to
    digest. Is this true? Is there any benefit to soaking nuts or seeds
    before eating them? Is there any benefit to eating them raw in the first
    place? Does roasting or heating destroy any of the nutritional value?

  • Sorry, completely disaree with you! I have been raw vegan for 10 months, have ZERO deficiencies, and am in optimum health! When I eat cooked vegan, I definitely do NOT feel as well, lack energy, and feel bogged down! While it IS true some vegetables nutrients are better absorbed if you LIGHTLY cook them, you can STILL get adequate nutrition through the raw ones as well if you know how much and what type of fruits/veggies/nuts/seeds to eat!

    • Vol

      A whole 10 months, wow.

    • Julio Cesar

      How could you digest all tha raw food? I have problems with too much raw salads. Give me headaches and abnominal pains.

  • Martin


    Is it a good or a bad idea to use lemon together with broccoli ? or to eat lemmon in the same meal as broccoli?
    Does lemon juice destroy glucosinolate or sulphoraphane ?

    also, I’ve heard that raw broccoli is dangerous for the thyroide gland . Would this apply to a huge intake of broccoli only, or to any quantity raw broccoli.

    thank you.


    • There is no science to the whole “food combining” thing. Our bodies are very intelligent. We don’t need to separate fruit from veggies or anything like that. This is just one of many fads with no scientific validity.

      Raw broccoli, or any cruciforms vegetable, is NOT dangerous for the thyroid. That is just a lot of hype. These foods are actually protective of the thyroid in regards to protecting it against cancer. Prior to going vegan, I was not very healthy and I had a thyroid problem. I was put on medication and after going vegan, eating a whole foods plant based diet with lots of raw kale, raw broccoli, etc. (as well as cooked kale, broccoli, etc.), I was able to get off thyroid meds :)

      To actually impact the thyroid, you would have to eat mountains of the stuff. So yeah, maybe someone eating nothing but raw kale for a week, and mounds of it, might experience some issues. But that would be true for anything eaten in such an unnaturally imbalanced and extremist way.

  • Shaylen Snarski

    I once read from a fairly reliable source, that protein from animal flesh (and secretions) isn’t properly utilized by our bodies because the amino acids are killed during the cooking process and therefore plant foods are a better source of protein. Regardless if this is true or not, I know that plant foods are a superior protein (and source of nutrients in general) than animal products for many reasons. But my question is about the cooking… I know quinoa is an excellent protein source for example, but I was worried the cooking process would render that protein useless, however after a tiny bit of research I found out that is not the case. So I was confused about the whole cooking/amino acids thing, so I just assumed that it was due to the extremely high temperatures required to prepare animal products which resulted in the destruction of the amino acids/usable protein.
    So basically my question is how would cooking help with protein absorption and is what I read about the amino acids being killed in animal flesh true?

  • Julio Cesar

    Eating too many raw plants gave me some headeches and stomach pains. They are hard to digest to me.


    Hey Doctor Greger, I have been vegan for over a year now and I am increasing the amount of raw foods and decreasing the amounts of cooked foods. Sometimes I get up to 90% Raw foods a day and the rest is cooked.
    Anyway, doesn’t the fact that our ancestors used to eat only raw food shows that we are suited to eat raw food?
    I know some vitamins as you mentioned increase or become easier absorbed by our body after cooking however, do we need to eat more than what the plants offer? Like, you might find food that are high in Iron like meat and etc even higher maybe than nuts however, doesn’t make it automatically better we may get enough by only what the plants offer.

    I was really surprised by the deficiencies that you mentioned in a raw diet. B12, vegans that eat cooked food they still need to supplement it because it mainly comes from dirt and since our foods are all washed and scrubbed it loses b12. Calcium, protein , Zinc selenium are found in high amounts in nuts/seeds and etc.. And I think fruits are a very excellent source of energy.

    Sorry correct me if I am wrong :) Thanks.

    • Thea

      ameen: re: “…doesn’t the fact that our ancestors used to eat only raw food shows that we are suited to eat raw food?” It is not a fact that modern human ancestors ate only raw foods. To the contrary. I have seen a compelling talk on how cooking our food is likely the main reason that humans brains became as advanced as they are. Our brains require a lot of calories. If we ate only raw food (presumably the type of raw food available historically), that would require a human to spend over 9 hours a day doing nothing but eating. That’s not practical. On the other hand, cooking food allows us to get a lot of calories quickly and easily. It frees up time for “humans to do interesting things with our neurons.” Here is a TED talk on this topic if you would like to learn more:
      We also keep learning that human use of fires/fire pits goes further and further back in time than previously thought. And also consider that some studies show that primates have a preference for cooked food over raw. So, it is quite logical to guess that some common primate ancestor started eating cooked food in such a way that allowed brains like those of modern humans to evolve.
      To be fair, no one knows exactly how human brains have evolved. But it is by no means a “fact” that the first humans ate only raw foods. Thus, I would say that any theories of human nutrition that people have need to take this into consideration. (None of which is to say that eating a certain percentage of raw foods in our diet is a bad idea. I’m not arguing for eating all cooked foods.)

    • The truth is is that it’s hard to peg down exactly how our ancestors ate (which is why the whole paleo nonsense is completely made up), but one thing is for sure, they ate what they could find region to region, season to season. They most likely ate insects on occasion, so should we, too? And our ancestors actually have been cooking foods for thousands of years. That’s actually one of the more likably theories as to why our brains are “so big” whereas for the longest time they tried saying it was due to meat consumption which is something that has been disproven over and over again.
      The best we can do now is look at science. Plus, our ancestors didn’t destroy the soil with toxic waste, so plants had an abundant amount of nutrition, much more than they do today. The best way to know how to eat is to look at the nutrients we’re getting today, not ten thousand years ago.
      I agree with you that fruits are a great source of energy. I feel amazing on raw food, but I personally find it hard to get all the nutrients I need from just raw plants (it WOULD be doable if I could afford them all! or if I had the means to grow them all right now, but I’d be eating A LOT of them), so I find great value in things like lentils, beans, hummus, potatoes, quinoa, etc. And I feel AMAZING on these foods as well! I often mix raw foods in with them. This is the diet that’s made me feel and look the best, personally.

  • Here’s something that irritates me about people claiming a 100% raw food diet is vastly superior… Most of them advocate against any extracted oils and when it comes to coconut oil, they’ll acknowledge the fact that there’s no real scientific evidence to the coconut oil craze. But then, why only acknowledge some findings and not others, such as the fact that there’s no scientific evidence that a 100% raw diet is superior? And can even be deficient. I respect everyone’s food choices so long as they’re cruelty free and as sustainable as possible (thus avoiding palm oil which is both cruel and unsustainable… and unhealthy). But I don’t like seeing people giving others advice to stay away from things like quinoa, lentils, beans, nuts, and even going so far as to say to stay away from potatoes, tomatoes, etc. There’s a lot of arrogance by a lot of these fully raw food advocates with very little science to back them up.
    That being said, the more raw the better. I love raw food! But I greatly value my cooked lentils, quinoa, black beans, sweet potatoes, etc. And I also like to enjoy what I eat and eat to live, not live to eat, which is something I see happening a lot in some of these extreme cases.
    If someone feels best on a 100% raw diet, that’s fine, good for them! But when they call others out for being on a “lower level of health” and other things I see and hear a lot… it’s like… really? Who are you exactly? Anndddd…. vent over.

  • Protein Deficient

    I eat starch based diet.
    However i don’t agree with what Dr Greger said on this video,
    Some nutrients are destroyed by cooking, but some nutrients become more absorbable, no doubt.
    But cooking also creates Carcinogens,
    Most material inside a cigarette is harmless before you lights it,
    It mostly plants, But right after those materials were burned, They become the most toxic materials to human health.
    So why to assume that cooking other healthy plants food will not creates toxins?
    Sure, burning is not exactly the same as heating (cooking),
    But their mechanism shouldn’t be much different.
    If cooked meat was proven to creates more deadly Carcinogens,
    Even though that plants are healthy , and Animal Foods are not,
    We can’t dismiss the possibility that cooked plants also creates Carcinogens,
    Most likely they will be much less toxic than cooked meat or cooked fish.
    But the presence of these toxins is a result of cooking nonetheless
    Many think that rotten meat is smell much worse than rotten plant,
    And it true! I agree! But guess what, rotten plant also may contain Maggots, just like
    Rotten meat, And if some one not agree, i suggest him to do the experiment by himself, By cooking sweat potato.
    and put them in a bag for a few days, in the room temperature.

    The reason of more than 95% of sickness death and disability in the world
    is not lack of nutrients, Quite the opposite. It is known for many years that restricting calories is associated with much higher longevity, and there are many evidence of people who were cured their deadly diseases such as cancer, simply by fasting!