Doctor's Note

Did we really evolve eating that many plant foods? See my video Paleolithic Lessons.

As remarkable as this story is, this is just the tip of the cruciferous iceberg! See, for example:

How else can we protect our immune function? Exercise (Preserving Immune Function In Athletes With Nutritional Yeast) and sleep! (Sleep & Immunity).

Given the variety and flexibility of most mammalian diets, a specific dependence on cruciferous vegetables for optimal intestinal immune function would seem overly restrictive, no? I address that in my next video, Counteracting the Effects of Dioxins Through Diet.

For more context, check out my associated blog post: Our Immune System Uses Plants to Activate Gut Protection.

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  • Stephy

    could u please make a video about cruciferous being goitrogenic ? and the whole iodine issue on a vegan/low or no sodium/ no seaweed- diet itself. I seem to be iodine-deficient since i m doing 80 10 10. No salt no seaweed. And i always ate a lot of cruciferous. Broccoli etc cooked but cabbage usually raw. Now i dont eat it anymore coz i m so afraid of the goitrogenic effect.

    • guest

      You should be ok if you cook your broccoli. Iodine is available if you eat a bunch of varied greens and fruit (my opinion). I am assuming you don’t eat cooked food, though. Maybe a bit of steamed brocc. ever once in a while if you permit.

      More importantly, if you are on 80 10 10 you are eating a a diet of lots of fruit sugar, as in 1500 to 3000 calories each day in fruit. Are you comfortable with this excess sugar not causing any long term problems internally? Do your pancreas and liver and hormones get screwed up by this? I do not know the answer but there seems to be concern. I love fruit but are we designed and enabled to eat excess fruit to this magnitude and not at some point suffer?

      • jilltheveggiequeen

        I agree about fruit. Our diet truly needs to contain many more vegetables than fruit in temperate climates. Perhaps in the tropics it is a different story.

        • Guest

          Have you been able to find any research that shows high fruit consumption is harmful? I don’t want to harm my pancreas and liver but I have not been able to find any studies online that have looked at this issue. But there are plenty of vegans online who claim that high fruit consumption is not good for us.

          • Christo Okulian

            I dont know exactly why high fruit consumptions is not good for us. would it because of the fructose… but truly it is over exaggerating if we eat a lot of fruit will harm our liver and pancreas. unless the “a lot” means “Too much” or qualified as illogical consumption like the soy consumption 5-18 servings in the other vid.

    • HappyPBD

      Dr. G has a video on goitrogens. You can look it up in the index or do a search for it on this page. I don’t think you need to be afraid of cruciferous vegetables goitrogenic effects, just cook them first to deactivate the goitrogenic effects

    • For those of you who are battling cancer, have a look at the research of the Cleveland Clinic’s Dr. Aleck Hercbergs. He has found that people with cancer who have low thyroid function have a better prognosis.

  • Connie

    is anyone studying he effects of taking a proton pump inhibitor on this mechanism. Reducing stomach acid doesn’t sound like it would be helpful. I stopped taking prevacid 2 years ago (after 14 YEARS) and am now concentrating on rebuilding magnesium and other nutrients I missed during that time. I’m also trying to alert my younger brother and sister to the dangers of PPIs. The FDA required statement on their ads is woefully insufficient! Thankyou Dr. G for all that you do. I plan to volunteer to help your site when I. Am back home…currently in CA looking after my 89 year old dad.

    • Dan

      Yes PPIs cause malabsorption of magnesium, B12, calcium and no doubt other important micronutrient vitamins and minerals. But for some people, they are a real lifesaver. Anyone on one should supplement with calcium+magnesium and B12; maybe zinc too.

    • Kathleen Holland

      The other little thing that happens with high doses of Nexium or PPI’s is the development of stomach polyps. I had hundreds of them and after stopping PPI’s and going to Zantac..H2 type acid reducer…almost all of the polyps are gone. I am hoping with my plant based diet that all will be gone eventually.

    • HereHere

      I’m glad to hear I’m not the only one here who is dealing with chronic reflux issue.This has not resolved for me, despite being plant-based and it can be tough to avoid spicy foods on this diet (but I do, and I’m very strict about that). My main vices are chocolate and eating late in the evening, so I guess I have more work to do!

  • Ilana

    What if already have IBD and are on immunosuppressants?

    • Elizabeth

      I would look into weaning off immunosuppressants and build your immune system with as much raw fruits and veggies, sprouts and fresh, green vegetable juices as possible. Also do your research on Low Dose Naltrexone for Crohn’s and Colitis. Two of our family members are on LDN for advanced Crohn’s Disease. You can go to
      Peace & Raw Health,

      • Ilana125

        Yeah I haven’t found any drs so far willing to let me off them. I haven’t had approval for LDN either. I was just wondering about broccoli and immunosuppressants….

        • HereHere

          I know someone who had Chron’s. He went vegan for ethical reasons and when I last spoke with him (1-2 years ago), he said his Chron’s had been in remission for 10 years, and that the hospital staff was so surprised they requisitioned the paperwork for his initial diagnosis (biopsy results, perhaps, or some kind of scan, I didn’t pay attention to the details at the time).

  • Darryl

    For those seeking more syllables, the most studied aryl hydrocarbon receptor (Ahr) ligand from cruciferous vegetables is 3,3′-diindolylmethane, produced by digestion from indole-3-carbinol, which is itself produced when cruciferous vegetables are injured (eg. chewed) from the glucosinolate glucobrassicin by enzymatic cleavage by myrosinase.

    While the related cruciferous vegetables (Broccoli, kale, cabbage, cauliflower, and Brussels sprouts are all cultivars of one species, Brassica oleracea) all have admixtures of several glucosinolates, the one that appears to have the most glucobrassicin is Brussels sprouts, followed by cauliflower, kale, and cabbage. So Ahr might be better called the Brussels sprouts receptor.

    • Thea

      Darryl: Really helpful post. Thanks! Of the cruciferous veggies, I like broccoli and cauliflower hte best. So, I was happy to see that cauliflower made it second on your list. :-)

    • HereHere

      Thanks, this is really helpful. The only thing going still in my garden are collard greens, and possibly a small amount of kale, so I was kind of relying on the collards for my main cruciferous supply. I’ll pick up some other ones in the produce store today.

    • How do broccoli sprouts and the sprouts of other crucifers compare to the mature vegetables in terms of glucosinolates? Do sprouts contain more/less than the mature plants?

    • Harriet Sugar Miller

      These intraepithelial lymphocytes are part of the lining of the large intestine, right? Do they also line the small intestine? To what degree?

    • And let’s not forget watercress! The Heidelberg cohort of the EPIC study found that watercress, out of many crucifers, was highest in glucobrassicin. The second highest was Brussels sprouts.

  • 1AndrewWalsh .

    can i have frozen broccoli. Someone told me that frozen broccoli has lost his sulfurophane . Is that true?

    • Darryl

      The flash-blanching of broccoli prior to freezing likely inactivates the myrosinase that cleaves glucoraphanin to sulforaphane. However, our intestinal bacteria also produce myrosinase that can do the conversion. Some is lost, but its also absorbed in a time-release fashion.

      From: Vermeulen, Martijn, et al. “Bioavailability and kinetics of sulforaphane in humans after consumption of cooked versus raw broccoli.” Journal of agricultural and food chemistry 56.22 (2008): 10505-10509.

      • 1AndrewWalsh .

        Thanks you so much…really helpful

    • Gross Bro

      Yes, however, “Consumers can even reinstate the cancer-fighting agent in broccoli themselves by steaming frozen broccoli with raw radishes, cabbage, arugula, horseradish, spicy mustard or wasabi”

      I steam the broccoli quickly with red cabbage and make a horseradish sauce to drizzle over just to be sure.

      Man do I love these massive broccoli, cauliflower, brussels spout, chopped asparagus, carrot, green bean, and onion salads I’ve been making! Unbelievably filling.

      • 1AndrewWalsh .

        Thanks I really appreciate your answer

      • Sam

        how long do you steam? do you steam radish too? does any radish work?

        does anyone know how to remove parasites from raw produce?

  • Chessie

    This is good news for those of us who love cauliflower. Can anyone clarify: If eating crucifers activates our immune system, what’s the difference between that and causing inflammation in our intestines? IOW, does the immune activation equal inflammation?

  • Dan

    This is very interesting. I recently had a severe reaction to eating kale involving 5 days of profuse diarrhea, abdominal pain, tenesmus and nausea. This is the first time I had ever eaten kale. I have found from the internet that such reports are not rare. I have no problem with cauliflower or broccoli or asparagus. I am a bit concerned about collard greens, since they are so closely related to kale.

    • HappyPBD

      Was the kale you ate raw or cooked? If it was raw, did you tenderize (massage) it first to break it down a bit. I’ve heard and read that raw kale can be hard on the digestive system. It can cause bloating, gas and other abdominal issues for some people. It sounds like this is what happened to you. If raw kale is the culprit perhaps cooked kale might be better on your GI system?

      • Dan

        It was both raw and cooked. I ate a small raw portion and a larger steamed portion. The diarrhea lasted 5 days and was severe.

    • Plantstrongdoc M.D.

      If RAW – maybe contaminated?

      • Dan

        Possible but I doubt it. I had no fevers and actually very little abdominal pain (just a bit of cramping). I think it was more like intestinal angioedema from the kale antigens. If you look online, there are a lot of stories like this. And for 5 days I could smell that kale on my breath every time I burped – it was very odd. I did eat a small amount of uncooked kale but the main portion was steamed for 5 minutes at heat.

    • Guest

      I too have had bad reactions to kale. Collards and swiss chard are problem for me as well. Spinach and romaine I am ok with. My best guess is that there are inherent properties in kale that are acting as natural pesticides, trying to protect itself. Maybe it isn’t so odd that bad reactions from kale and some other greens exist. It makes me realize that even when a foods is “so good for us” it doesn’t mean we should eat it. Sort of a zen-saying, but it makes sense.

      • Guest

        ….but there are plenty of people who do fine with kale and such, so one is left to find out which camp they fall into.

      • Dan

        Will stay away from collards and swiss chard then!

  • jilltheveggiequeen

    Thank you so much for this. I am into good guts and great vegetables, as you know. This reinforces what I already know and makes it even more important for my next book Nutrition CHAMPS to come out. The C stands for cruciferous vegetables. Yippee. Keep up the great work.

  • Craig

    Outstanding!! I have family that owned Mann Produce in California. They were the first to start broccoli slaw. I forwarded this to the patriarch of the family. Eat Your Broccoli. I end all my correspondence (almost) with this. Thank you.

  • Plantstrongdoc M.D.

    I knew it – broccoli rules !

  • Rachelle

    Dr. Greger,
    Can you please comment on whether eating cooked cruciferous vegetables, whether from frozen or cooked from fresh raw provides the same result as you describe in this video?

  • Ji Kang

    So what I take from this video lesson is that to try eating cruciferous vegetables at every meal. The bar has been set higher in consuming more dark leafy greens. I accept the challenge!

  • Dan

    I have similar questions to the others:

    1) Is it best to eat these veggies in a smoothie, to break down their cell walls and release their phytonutrients?

    2) And if you get far more nutrients from a smoothie than raw unbroken-down versions, do you still have to consume that smoothie three times per day?

    3) Are frozen veggies as good as fresh?

  • Liz

    Hello, I am very interested in foods that do not contain sulfates or how to get rid this toxin . My daughter has developed an intolerance to these substances resulting in painful migraines. I’ve read that all her favorites/most nutritious have them, such as broccoli, grapes, eggs, citrus, onions,etc. What can we do?

    • Thea


      PCRM (Physician’s Committee For Responsible Medicine) has a great page talking about migraines and listing safe foods and foods to avoid. The page also gives you a step by step approach for figuring out what the food triggers are and thus now to avoid them:

      Also, while eggs may be one of her favorites, they are definitely not nutritious. (It’s not even legal for the egg industry to claim that eggs are nutritious in their advertising.) So, getting rid of that food is nothing to be sorry about. You can learn more about eggs in the following video as well as many of the individual videos here on

      Let me know if you have concerns about how to feed a child a healthy diet after eliminating meat, dairy and eggs. I have a recommendation on that too.

      Best of luck to you and your daughter.

  • fahdutnik

    video, sound so soft could not hear it.

    • ShaneJax

      Volume is fine here. Might want to make sure your youtube volume is up.

  • Mark

    Broccoli is such a super food it seems. I always feel bad when i throw away the broccoli stalks when i cook them. Are the stalks nutritious to eat?

    • Thea

      Mark, My understanding is that the stalks are nutritious. And they are edible too. Just cut off the outer/skin hard part. The inner part might take a bit longer to cook, but it cooks up great/soft. I make “coin” shapes of mine.

      Another idea: my dog loves to eat the coins raw. So, then you would at least not be throwing them away and your dog (if you had one) wouldn’t get fat. :-)

      Just some ideas for you.

      • largelytrue

        Cool! Now I know of another dog that likes this sort of snack! Does your dog also go for cabbage cores and nubs of cauliflower? One thing that dogs really seem to love is the trimmed tips of fresh green beans. These are both sweet to their taste and extremely easy to eat.

        • Thea

          largelytrue: My dog adores cabbage! He also likes the cauliflower “nubs”. I haven’t played too much with green beans, but my dog will drool for sugar snap peas. We often split a bag. :-) (Where my dog gets his as part of training or mental enrichment games throughout the day.)

      • Thea,
        These intraepithelial lymphocytes are part of the lining of the large intestine, right? Do they also line the small intestine? To what degree?

        • Thea

          Harriet: I’m sorry, I don’t know the answer to your question. I’m not a doctor or RD, etc. I don’t have a medical background. I hope you find your answer.

    • largelytrue

      The stalks are delicious and sweet (in part due the inulin, I think), and their being in an edible condition (rather than dry and cracked) is a sign that you still have fresh broccoli. Cut off the bottom of the stems and trim any particularly gnarly bits on the skin, but I disagree with Thea and find the skin to be perfectly edible in general. Coin shapes are okay but you may also try slicing them lengthwise to lengths of about an inch or so. If you really wanted to get fancy you could mandoline the stems together with, say, some carrots, and have the base of a nice pickle or salad.
      Food for thought: brassicas have been cultivated in every which way. For every plant part you can think of, there’s a brassica which has been bred explicitly so that people can get a good crop from that part. Kohlrabi is roughly what you get when you try to grow a plant with giant broccoli-style stems.

      • Where is the inulin in broccoli?

        • largelytrue

          The stalks? Didn’t I say that?

          • Yes, you did. But is it only in the stalks? Or is there inulin in the flowers, too? Thanks, largelytrue.

          • largelytrue

            I don’t have a detailed map on hand, but inulin is water soluble and functions as energy storage and frost resistance for a plant; loosely speaking it does some of the things that fat does for the animal kingdom, but you’d be more likely to find it in the fleshy parts and the plant’s fluid systems than in the ‘skin’. Therefore I’d still say that the interior soft part of the stem is likely to have the bulk of the inulin in a broccoli tree. The buds may take up some extra inulin under cold stress.

  • Darryl

    What happens when a top ad agency gets the broccoli contract.

    Yeah, Kuck Fale.

  • Dear Dr. Greger,

    My husband and I truly appreciate all you’ve done to share the latest in nutrition info with the world!

    We became whole foods vegans 2 years ago and it has made great changes in our heath, especially my husband’s! We’ve both lost weight and are BMI 20-22, but the big thing is his T2 diabetes is close to pre diabetes levels, his blood pressure is mostly under 140/80 without meds and his cholesterol is 180 without statins (it was over 300 before we went vegan).

    He strained the muscles in his back 4 months ago and has been in pretty constant pain since. We found a back specialist who diagnosed him with Diffuse Idiopathic Skeletal Hyperostosis (DISH or Forestier’s Disease).

    The doc told him to do yoga, Pilates and swimming, along with taking Ibuprofen to reduce inflammation. We eat lots of antioxidant foods which should also be anti inflammatory but were looking for a source to tell us the most anti inflammatory foods to eat. He wants to reduce inflammation with food rather than pills.

    What are your suggestions for the best foods to reduce the inflammation and pain in his back?

    Thank you,