Doctor's Note

If you’re new to sulforaphane, check out my videos, Broccoli Versus Breast Cancer Stem Cells, and Sulforaphane: From Broccoli to Breast. For more on raw food diets, check out my videos Raw Food Diet MythsBest Cooking Method; and Raw Food Nutrient Absorption. And for more on keeping our good bacteria happy, see all my videos on gut flora, including one on how the phytonutrients in flax seeds go through a similar transformation in our gut: Just the Flax, Ma’am.

Note that one of the sources for this video is open access, so you can download it by clicking on the link in the Sources Cited section, above.

For more context, check out my associated blog posts: The Best DetoxBroccoli Boosts Liver Detox Enzymes; and How Probiotics Affect Mental Health.

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  • Michael Greger M.D.

    If you’re new to sulforaphane, check out my recent videos Broccoli Versus Breast Cancer Stem Cells and Sulforaphane: From Broccoli to Breast. For more videos on raw food diets check out Raw Food Diet Myths, Best Cooking Method, and Raw Food Nutrient Absorption. And for more on keeping our good bacteria happy, see these 9 videos on gut flora, including one on how the phytonutrients in flax seeds go through a similar transformation in our gut, Just the Flax, Ma’am. Then of course there are hundreds of other videos on 1200 or so topics. Note that one of the sources for this video is open access, so you can download it by clicking on the link above in the Sources Cited section.

  • Thea

    I LOVE this video. It does so much to clarify the raw food movement and also finds a way to allow me to eat cooked broccoli and still fight cancer.

    I was starting to get a sick feeling in my stomach at the beginning. Was I going to have to find a way to eat broccoli raw? Please, say it isn’t so! I have enough food challenges as it is. Thankfully, not only do I have a maximum-healthy way to eat cooked broccoli, but I can justify all those packages of pre-chopped (organic) broccoli that I buy from Trader Joes. Yeah!

  • GetSkinnyGoVegan

    Love that book “Becoming Raw”. Tim VanOrden is the only other super down to earth raw foodist (that I know of) that talked about the “enzyme myth”. He talked a lot about AGE’s and PAH’s (when cooked) and how a lot of the benefit was what we avoided when eating raw food. And it was one of his videos that got me to try frozen broccoli in smoothies! With bananas & mangos & now a teaspoon of Amla, it’s truly superfood. I also love that in the “Becoming Raw” book, it talks about iodine, seaweed and contaminants. My takeaway was buy good brands that test for metals & don’t ever eat hijki!

  • LowFatVeganChef

    Good to know. My husband Frederic Patenaude actually wrote a book called Raw Food Controversies, lol. Although we promote a high raw diet we never used the enzyme theory as a reason to only eat 100% raw foods as you miss out on so many healthy vegetables and greens most people don’t want to eat raw.

    So I teach people how to eat more raw food and healthy oil free vegan foods at

    Love your work Michael, we saw you speak at the Advanced 3 Day Weekend and got all of your Nutrition Facts DVDs. :) Science rules!

  • Elvin

    Regarding cooked vs raw, although it is not the same nutrient under discussion, is it not the case that this clip and the one at contradict one another? That being so, it would appear that the best way to eat broccoli is by using the chopped-then-cooked method.Because: either etaing raw, or eeating directly cooked is going to result in the non-availability of one thing or another.

    • DStack

      Or just get your fix of sulforaphane from broccoli sprouts and steam away without worrying about how you chop or when you cook!

  • Elvin

    And what is the optimal degree of choppédness of the broccoli? In the country where I live there is no such thing as store-bought frozen pre-chopped broccoli, so I’ve never seen it, but I would imagine that where it does exist, it is simply individual florets — not terribly small ones at that– cut off of the stalk. Is that all the choppédness required? That would not be much, and it is difficult to imagine it having much effect.

    • MarthaLA

      I would imagine the ‘optimal degree of choppedness of the broccoli’ is as close as possible to thoroughly chewed broccoli, and can be achieved by a food processor or a blender.

  • vegan2u

    I have a great method that I didn’t realize was doing me such a great favor, I buy fresh dandelion greens, watercress and fresh bulk broccoli/purple or yellow cauliflower, I then put the broccoli/cauliflower in a freezer bag and the other two in a freezer bag and freeze them overnight. The next day I pound each bag with a 3 pound hammer until they are powdered. Then I just add them to my morning Vitamix green smoothies or use them to make stews at night. It works great! However, On a different topic where I don’t feel that I’ve done well, I recently saw a video by Jeff Novick on YouTube ( (Go to the 10:29 mark to save time) where he points out a study that dispels the notion that fiber will fill you up a greatly suppressing any cravings that you would otherwise have. Fiber in its natural form is different than a blended form, as you will see in the video. My question on that though is this, aren’t we suppose to chew are food until it is liquid? Isn’t that the same as blending? Jay

  • GeorgeI

    Hi Dr. Greger.

    Interesting information. I wish you would have presented it in a different way. I’m concerned it will encourage some people with wacky raw foodism beliefs. No disrespect to you or anyone else.

  • HappyHerself

    Dr. Greger, how do you steam foods in a glass pot? Our steamers are all Revereware stainless steel that fit into Revereware stainless steel pots. We do have some Corningware pots but none have steamers with them.

    After you mentioned Brenda Davis’ BECOMING RAW in this video, I bought a copy and have reached page 56, where Vitamin E is discussed. Davis says, “An unexpected finding was that metal containers may interact with Vitamin E to increase its losses. For example, peas steamed in a metal pot had vitamin-E losses of up to 70 percent compared to no losses when a glass pot was used.” (Chapter 4 footnote 105)

    Puzzled and hoping to retain Vitamin E in our steamed (or simmered or boiled, which weren’t mentioned) foods, I’m considering what we might need to change in our cooking procedures. Two containers are involved for steaming, the lower one holding liquid (which we keep and use afterward for cooking rice or quinoa or soup or oatmeal), and the perforated container which holds food above the simmering liquid. There’s also a metal lid that gathers condensation which is returned through the food and perforated container to the lower container.

    I’m wondering if using steel cooking pots and pans negatively affects the quality of other nutrients, as well. If so, is that significant? The Vitamin E losses sounded significant. What kind of containers should we be using for cooking?

    I am perplexed.

    Thank you!

    • Guest

      I know nothing of the chemistry you’re concerned about, but you might want to try a bamboo steamer with your Corningware pots. A bamboo steamer rests on top of a pot and doesn’t need an exact fit to work well.

  • Great information. I happen to have the Davis and Melina book, “Becoming Raw”. It’s indeed a great and sound book.

  • deana209

    Dr. Greger,
    I thought I heard 40 minutes in the video – is there any good data on how long to wait after chopping for maximum sulforaphane content?

  • Johnotvos

    Michael, perhaps you could do a blog on juicing and its purported benefits regarding more enzymes released into the blood stream.  Talk about whether we don’t need the fiber from foods juiced etc. Also, what enzymes are in our gut and if they are really diluted through drinking water with a meal.

  • Michael Greger M.D.

    For some context, please check out my associated blog post The Best Detox!

  • bellybuttonblue
    • Toxins

      Sulphorophane, what makes broccoli so great, is increased with cooking as your article points out.

      • Would you consider 60 C cooking? That’s like 140 degrees Fahrenheit.

        • Toxins

          No I wouldn’t! I didnt realize the temps were so low, i quickly skimmed the abstract in this situation. Thanks for pointing that our Dr. G!

  • Sheila Kawakami

    Thank you so much, Dr.Greger, for all the time and effort you put into making your videos! They are highly infomative and interestingly done too! Regarding sulphoraphane, I understand that broccoli sprouts have about 40 times more than broccoli florets, and they are very edible raw. Thought this might be helpful too, for those interested in this topic.

  • So what is the 2nd example of a plant enzyme that serves a physiological function? (You mention there are 2 at the onset of the video)

    • My guess is that it’s the allinase in allium vegetables, which turns the inactive alliin compounds into active forms of sulphur. Am I right?

      • Corina-Aurelia Zugravu righy

  • Johann Gabriel Andersen

    What about mixing some raw broccoli with the salad, assuming that you would in any case be having some salad? Would that not assist the cooked broccoli in energising the gut actions?

  • Harriet Sugar Miller

    Are you certain that the glucosinolates in cut broccoli last a long time?

  • linda

    Do you get the sulforaphane when making a raw juice with broccoli or it has to be chewed to get the benefit

    • DStack

      Juicing is essentially the same function as chopping/cutting the broccoli, so as long as you’re juicing it raw, you should be unleashing even more sulforaphane by juicing it.

  • Would you mind giving us the source of your statement that cutting broccoli and letting it sit 40 minutes allows the enzymes to produce healthy glucosinolates that are not later destroyed by cooking?

    • BRJ

      Did you ever receive the info on the sources/ scientific studies/ you requested here?

      • No, I never got a response other than “Dr. Greger suggests” doing this. I know there’s research on alliums suggesting you need to cut them and let them sit but I haven’t seen any research on crucifers. It would make sense though. I’m going to ask a crucifer researcher what she thinks.

      • I communicated today with the food scientist who discovered the value of combining raw and cooked crucifers, and she says that no, you do not need to cut crucifers and let them sit. You just need to chew them well in order to activate the myrosinase.

  • And somewhere in this mass of interesting work, you state that indoles in crucifers increase with cooking? What’s the source of that statement?

  • Sebastian Tristan

    It’s really too bad broccoli give me a lot of gas, especially raw broccoli.

  • johnnywhite

    What, I wonder, sulforafane-wise, is the effect of pickling vej, by salt, or koji?

  • Laura

    I have been on a whole food plant based diet for the last 2 years. Over the
    last 2 years, I have experienced some bouts of afib. Over the last month, I have changed to predominantly raw food. Since my change, I have not had any fluttering at all. Why? Can you explain that if its not the raw diet, then what? Nothing else has changed.

  • Shaun D

    I have read that nuts and seeds contain enzyme inhibitors and therefore require soaking and slow drying before consumption. Is this correct. Is it unsafe to eat nuts and seeds straight from the store?

  • Taggart

    Mai I ask how much chopping constitutes chopping? Is it enough to just break the broccoli down into the individual florets or do you need to slice it all into 1mm thick slices, in order to ensure sulforaphane production?