Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Also, there are 1,449 other subjects covered in the rest of my videos--please feel free to explore them as well!

  • 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.

    • Robert Freedomfighter

      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.

  • 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?

    • Don Forrester MD

      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?

  • 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.

  • Ana S. Cunha Vestergaard

    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

      • Tiernan Mark Ryan

        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. ;)

  • Padric O’Fish

    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

  • Calvin Leman

    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.

    • Don Forrester MD

      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 :)

    • Don Forrester MD

      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?

  • 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.

  • Sean Carney

    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.

  • 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,