How to Cook Broccoli

Second Strategy to Cooking Broccoli
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When I used to teach medical students at Tufts, I gave a lecture about this amazing new therapeutic called “iloccor-B.” I’d talk about all the new science, all the things it could do, its excellent safety profile. Just as they were all scrambling to buy stock in the company and prescribe it to all their patients, I’d do the big reveal. Apologizing for my “dyslexia,” I would admit that I’d got it backwards. All this time I had been talking about broccoli.

The main active ingredient in broccoli is thought to be sulforaphane, which may protect our brains, protect our eyesight, protect our bodies against free radicals, boost our detoxification enzymes, and help prevent and treat cancer.

In my videos The Best Detox and  Sometimes the Enzyme Myth is the Truth, I talked about how the formation of sulforaphane is like a chemical flare reaction, requiring the mixing of a precursor compound with an enzyme, which is destroyed by cooking. This may explain why we get dramatic suppression of cancer cell growth from raw broccoli, cauliflower and Brussels sprouts, but hardly anything from boiled, microwaved or steamed (except for microwaved broccoli, which actually retains some cancer fighting abilities). But who wants to eat raw Brussels sprouts?

There is a strategy to get the benefits of raw in cooked form. In raw broccoli, the sulforaphane precursor, called glucoraphanin, mixes with the enzyme (myrosinase) when you chew or chop it. If given enough time—such as when sitting in your upper stomach waiting to get digested—sulforaphane is born. The precursor and sulforaphane are resistant to heat and therefore cooking, but the enzyme is destroyed. No enzyme = no sulforaphane.

That’s why I described the “hack and hold” technique—if we chop the broccoli, Brussels sprouts, kale, collards, or cauliflower first and then wait 40 minutes, we can cook them all we want. The sulforaphane is already made; the enzyme has already done its job, so we don’t need it anymore.

When most people make broccoli soup, for example, they’re doing it wrong. Most people cook the broccoli first, then blend it. We now know it should be done the exact opposite way. Blend it first, wait, and then cook it.

What if we’re using frozen broccoli, though? In my video, Second Strategy to Cooking Broccoli, you can see the amount of sulforaphane in someone’s body after they eat broccoli soup made from fresh broccoli versus from frozen broccoli. The difference is dramatic. Commercially produced frozen broccoli lacks the ability to form sulforaphane because vegetables are blanched (flash-cooked) before they’re frozen for the very purpose of deactivating enzymes. This prolongs shelf life in the frozen foods section, but the myrosinase is dead by the time you take it out of your freezer. It doesn’t matter how much you chop it, or how long you wait, no sulforaphane is going to be made. This may be why fresh kale suppresses cancer cell growth up to ten times more than frozen.

The frozen broccoli is still packed with the precursor—remember that’s heat resistant—and we could get lots of sulforaphane out of the frozen broccoli by adding some outside enzyme. Where do we get myrosinase enzyme from? Researchers just buy theirs from a chemical company. But we can just walk into any grocery store.

All cruciferous vegetables have this myrosinase. Mustard greens, a cruciferous vegetable, grow out of little mustard seeds, which we can buy ground up in the spice aisle as mustard powder. If we sprinkled some mustard powder on our cooked frozen broccoli, would it start churning out sulforaphane? We didn’t know…until now.

Boiling broccoli prevents the formation of any significant levels of sulforaphane due to inactivation of the enzyme. However, researchers from the University of Reading found that the addition of powdered mustard seeds to the heat processed broccoli significantly increased the formation of sulforaphane. In the video I mentioned earlier, Second Strategy to Cooking Broccoli, you can see the amount of sulforaphane in boiled broccoli versus the amount after half a teaspoon or a teaspoon of mustard powder is added. Both a half teaspoon and a full teaspoon increase sulforaphane by the same amount, suggesting that we could use even use less mustard powder for the same effect. Therefore, although domestic cooking leads to the deactivation of myrosinase and stops sulforaphane formation, the addition of powdered mustard seeds to cooked cabbage-family vegetables provides a natural source of the enzyme such that it’s practically like eating them raw.

So, if we forget to chop our greens in the morning for the day, or are using frozen, we can just sprinkle some mustard powder on top at the dinner table and we’re all set. Daikon radish, horseradish, or wasabi—all cruciferous vegetables packed with the enzyme—work as well. Just a quarter teaspoon of Daikon radish root for seven cups of broccoli worked—just a tiny pinch can do it. Or you can add a small amount of fresh greens to your cooked greens, because the fresh greens have myrosinase enzyme that can go to work on the cooked greens.

I love kitchen chemistry—it totally revolutionized my daily greens prep. One of the first things I used to do in the morning is chop my greens for the day, so when lunch and supper rolls around they’d be good to go. But now with the mustard powder plan, I don’t have to pre-chop.

This helps explain the results I presented in Raw Broccoli and Bladder Cancer Survival.

OK, but what’s so great about this sulforaphane stuff? For a taste, see:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live year-in-review presentations Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Jessica Spengler / Flickr

  • Julie

    I love these practical tips! Just cut up broccoli, kale, cauliflower, collards etc 40 minutes before cooking, or add mustard powder, daikon or other raw cruciferous after cooking to get all the benefits these wonderful vegetables provide.

    • george

      Just last Saturday, at Trader Joe, I found a product called riced cauliflower, which is cauliflower chopped into small pieces the size and shape of a grain of rice. Inside the bag, it looks like cooked white rice. I added it, uncooked, to pasta and also sprinkled on a salad. Assuming that the chopping had created at least some sulforaphane, I tried to cook it into a curry but ended up with a dish that looked and felt like fried rice! One disadvantage of this product is, to my nose, it smells worse than whole cauliflower.

      • Julie

        Riced cauliflower sounds really interesting and like a fun way to serve cauliflower. Maybe what you smelled in the cauliflower that had been cut for so long was the sulforaphane as it’s one of the substances that gives crucifers their distinctive smell. I bet you could make it yourself and thus fresher by whirring up cauliflower florets in a food processor.

        • Tom Goff

          Yes, I occasionally put my cauliflower into a blender and use it as a rice substitute. It’s more expensive than brown rice though.

  • basehitz

    Your March 2012 video changed the way I prepare greens. This post gives more ideas. When I started studying your website (and I do mean study), I had frequent symptoms of multiple chronic diseases and ulcerative colitis had been wildly out of control for 2 years. All have reversed and the UC has been in complete remission since early 2015 when I made the last major transition toward WFPB diet. I year later it remains in full remission with only 1/4 the prescribed medication. I hope to go to zero. Frequent chest pains have stopped. Ditto head pains (my family has a lot of stroke victims). Chronic hypertension is now reversing and my cholesterol is 170 total, and still dropping. Even the arthritis (or what it felt like anyway) has almost completely dissipated. No medication was used for any of these other problems that I wasn’t even trying to solve. I would have been content just to stop the internal bleeding. I am very grateful and appreciative you collected all this in a book. Pre-chopped broccoli, collards and kale are a daily event. And after going through your entire library (taking notes in my offline library), I still learn from you.
    Very, very grateful.

    • Thea

      basehitz: Wow. That’s such a powerful story. Thank you for sharing.

  • Jim Felder

    You didn’t (this time) mention the most powerful way to get your sulforaphane and that is in broccoli sprouts. Just a ounce or two of sprouts on your salad is as good as eating a pound and half of raw broccoli. Can’t stand the flavor, here is one idea, add them to your breakfast smoothie (if you can hide a couple of cups of kale or spinach in a smoothie without making it taste like a liquid salad, then a half cup of sprouts should be no problem). Rather than put them straight in blender, I think there might be advantage to grinding them up in a mortar and pestle so that the glucoraphanin has time to mix with the myrosinase before being diluted in the large amount of other liquids in the smoothie.

    • Alexandre

      I have a really hard time sprouting the seeds .. they usually get modly.. any ideas on how to avoid this? thanks

      • ryan winsauer

        1. Soak seeds 6 hours (times vary for dif seeds, this is broccoli) completely submerged in water in a mason jar in a dark, area that is room temp (kitchen cupboard)
        2. Strain water out after the 6 hours and add a protective material that will allow air, but not bugs, through. Examples: paper towel laid on top, sprayed with a spray bottle which will seal it to the ring of the bottle. Alternatively: shirts, cheesecloths, etc are great with a rubber-band to keep them a hold.
        3. Twice a day (I get away with once a day too, but ideally, twice) fill the jar with water until the seeds/sprouts are submerged. Then strain the seeds to remove water and put the protective material back on top. If you are getting mold, it could be because after you strain, you aren’t paying attention to how much water is collected in the bottom of the container afterward. You should strain them, put the jar down, wait 30 secs and then observe to see if there is water collected in the bottom. You don’t want water collected, you just want the seeds/sprouts to be wet from the wash/rinse.
        4. Sprouts will have decent length in 3-5 days. I like to put them near light once they have a good root length and the cotyledons (first leaves) are visible. This will turn them nice and green to ensure that you’re getting those healthy chloroplasts in your belly.
        5. Oh and one last thing, don’t mistake root hairs for mold. Roots grow tiny lil hairs that could resemble mold if you don’t know it, but really, they are just trying to reach out any way they can for the liquid gold they love and those lil root hairs give them a bit more surface area of absorption.

        Hope that helps

        • Alexandre

          woooaahhh ryan thank you so much!! are does tiny lil hairds white lil hairs? :D ahah

      • fencepost

        Mine don’t sprout in my cold kitchen in the winter, but they sprout fine the rest of the year. Positioning the sprouting jars near a heat source, such as on top of the fridge, might help. The websites of companies that sell seeds to gardeners might show the optimum sprouting temperature.

      • I use the Vogel Biosnacky Seed Sprouters (jars) and never have an issue. As has been mentioned already, the change the water twice a day and rinse a few times. You can always add a pinch of salt (liquid salt solay is great) or sodium bicarbonate to help kill any bugs in there; just rinse a couple of times after. Once they look ready transfer to a container/bag for storage on the fridge. Don’t over grow them as that often leads to mould in my experience. Good luck

  • Jim Felder

    If I used my favorite salad dressing, a simple mix of balsamic vinegar and Dijon mustard, to dress cooked broccoli would there be enough myrosinase in the prepared mustard to react with the glucoraphanin in the cooked broccoli (or brussel sprouts, etc), or should I also mix in some powdered mustard?

    • Thea

      Jim: This question was asked back when Joseph was here. He guessed that since prepared mustard is cooked, that prepared mustard would not work.

      • guest

        Jim and Thea: Even some commercially available mustard powders are irradiated with UV light, which is known to denature proteins. The best choice would be to buy whole mustard seeds and grind them at home.

        • Jim Felder

          Thanks to both of you!

          • disqus_frJ9d7ZebX

            I used a pepper grinder on fine to grind brown mustard seeds which does not subject them to the prolonged heat (140F heat during the several hours required in mustard making), then added to mayonaise with a bit of honey for a great tasting honey mustard good for sprout “powerhouse” sandwiches and as a dressing for blanched or microwaved Broccoli. Also used some sour cream and probably greek style plain yogurt would work well. To me it tasted better than prepared mustards. Mustards also use a lot of vinegar–not sure if that low a pH damages the enzymes.

  • Dani

    In “Eating on the Wild Side” Jo Robinson says to chop or press garlic ten minutes before exposing it to the heat of the pan in order to get the benefits of eating garlic. She says this not true for onions.

  • Alexandre

    what I use to do is eating raw purple cabbage..maybe its just 1/4 the Sulforaphane but it’s easier to do. By the way, I think Ive read/heard somewhere Dr Greger saying purple cabbage has the same antioxidants as berries? Does anyone know about this? Thank you :)

    • george

      Yes, purple cabbage has anthocyanins, hence the purple color. Berries also have anthocyanins. But anthocyanins are not one compound but a class of compounds, so it’s good to eat a wide variety of things containing anhocyanins so as to get the whole spectrum.

      • Alexandre

        thank you so much for the reply george!

  • HaltheVegan

    I find that a convenient way to try and add “sulforaphane” to my diet is to blend broccoli sprouts with a small amount of water to make a thick liquid and then add it to a soup after the soup has been heated. Does anyone know if this method would allow the sulforaphane to be generated? I also add mustard powder to the soup as an additional measure. Thanks in advance for any responses.

    • Julie

      Yes, I’m sure that blending broccoli sprouts activates the production of sulforaphane. However, you’ll still need to wait the requisite 40 minutes after blending before subjecting the pureed broccoli sprouts to heat.

      • HaltheVegan

        Thanks, Julie!

  • ryan winsauer

    Michael, I think this should be the “if you have to” and not a replacement for getting the Sulforaphane naturally from the plant source (vs the Mustard Powder which has been dried etc). Sounded to me like you are saying that this is your “go to” for convenience now. Absolutely nothing scientific from that notion, but if it can be produced naturally from a fresh, living tissue, why not? Just a thought.

  • Marie

    Is it better to add the ground mustard before or after cooking the broccoli?

    • Thea

      After. The point of adding the mustard powder is to supply an ingredient that goes away with high heat. So, if you are starting with pre-cooked broccoli (i.e., frozen), you can maximize the cancer fighting properties of the broccoli by adding in the mustard powder after the broccoli has been heated up.

      • Marie

        Thanks! I understand now.

  • collardgreen

    I endorse this message!

  • Seeker2be

    I was thinking what about adding freshly ground broccoli seeds to your frozen broccoli?

  • kb2016

    Wonderful and so helpful. Does anyone know whether or not enzymes are preserved if I cut the broccoli, wait 40 minutes and then freeze it — then cook when needed? Thanks so much.

  • alphaa10

    For years, I knew the value of sulforaphane in cancer prevention, but was puzzled until now about how to get enough in the daily diet– and consistently enough to make a major preventive (therapeutic) difference.

    Dr. Greger’s gems of nutritional magic are an enormous daily benefit to me, as I discover the wealth of research he makes available– often, for the first time, anywhere.

    What a wonderful idea it has turned out to be to trust the lay public to understand ground-breaking new research into nutrition.

    Dr. Greger began his medical career in hope of bringing about the same marvelous health benefit he witnessed as a boy with his grandmother, who was wheeled into a Pritikin clinic but walked out by herself.

    So, a Valentine to Dr. Greger for all the good work he, his staff and volunteers do every day.

  • TR M

    Well that will change the way I prepare my kale. I grow lots and usually store it in the freezer but I’ll start chopping it up first, leave it for a bit and then freeze it. It will take less room in the freezer as well. I use it in smoothies a lot so it’s going to be put through a blender anyway. Or add some powdered mustard seeds to my smoothie. Don’t know how that would taste.

  • How finely must a cruciferous veggies be cut/chopped to create sulforaphane, i.e. are those packs of broccoli & cauliflower florets sufficient, or must they be really chopped finely?

  • nnmlly

    Raw broccoli is so much more delicious than cooked.
    Especially dipped in homemade turmeric mayo.
    It’s a win-win!

    • Hal

      Would regular mustard work to pull out the sulforaphane vs. the m. powder? Plain org. yellow mustard sure sparkles up a vegan salad, bean dish, and or the right soup/stew/goulash, and a plethora of old schooldays recipes-turned-vegan. (PS: Can the HUS dept. you direct choose a name other than PH&Animal Agriculture? It would add a lot of torque to your indescribably excellent work).

  • Gaby Schläpfer

    How about adding canola oil? Since canola is a mustard plant?

  • JimboD143

    What about precut, bagged fresh kale? I noticed that Wegmans just started selling it. I would assume that the sulforaphane is present there and has already mixed with the enzyme…

  • D.A.

    Would adding raw broccoli sprouts to cooked crucifers work to max out the sulforaphane availability? They are a raw crucifer, clearly, but I’m wondering if sprouting messes with the mechanism or if maybe it’s not fully developed yet in the young sprouts?

  • Mark

    would prepared (jarred) mustard work, such as Dijon or stone ground mustard?

    • disqus_frJ9d7ZebX

      Both yellow and Dijon mustard are subjected to heat of 140 or more degrees during a long grinding period and also to heat from high speed blending. According to Dr. G heat destroys the necessary enzyme and is likely why he recommends powder which may be subjected less to heat. I supposed you could just use a mortar and pestle to grind them yourself. Don’t know if a pepper mill will grind them they seem tougher than black pepper berries and an electric spice grinder will add a bit of heat, I know it adds a lot of heat to coffee beans which is why people use burr grinders instead.

      • disqus_frJ9d7ZebX

        ….Oxo pepper grinder on fine setting works well on brown mustard seeds

  • Qempner

    Are there no differences in the biological activity of myrosinase between different crucifera?

  • John

    I have a general question about prepared vegetables. My favorite way to cook vegetables and my best way to enhance vegetable input for my family is roasting. I know must time steaming it’s the best, but do you think with most roasting vegetables all the time it’s still ok?
    And a second question do you have studies for nutrition loss from however cooked vegetables that are stored in the fridge? So would it be very negative to pre roast (etc.) some veggies and pack them in the fridge for, let’s say 3-4 days?

  • Karl Young

    I eat a majority of my broccoli raw so haven’t thought much about hack and hold though it’s nice to be aware of re. preparing dishes with cooked broccoli. But I was curious as to whether there are any health benefits at all from cooked broccoli sans hacking and holding ? E.g. I sometimes like to order broccoli dishes at restaurants. Would it be better to skip the restaurant broccoli dishes in favor of dishes with other veggies whose health benefits survive cooking ?

  • Ali

    Food for thought :) I just read the following on Wikipedia. So what should we do then? :)

    Isothiocyanates, the primary product of glucosinolate hydrolysis, has been known to prevent iodine uptake in the thyroid, causing goiters. [25] Isothiocyanates in high concentrations have also been known to cause hepatotoxicity, or liver damage.[4] However, more recent studies have shown that diets high in glucosinolate-containing vegetables such as dietary brassicas have been associated with lower risks of heart disease, diabetes, and cancer.[2] [26] Isothiocyanates have been shown to induce phase II detoxification enzymes involved in the xenobiotic metabolism of carcinogens.[27] There has been increasing evidence to suggest that a myrosinase-like enzyme may also be present in members of the human gut microbiome. Although myrosinase, like many enzymes, will be denatured at high temperatures and thus lose its activity when cooked, a gut microbe capable of catalyzing the same hydrolysis of glucosinolates would be able to activate ingested glucosinolates into their more potent forms, e.g. isothiocyanates. [28] [29]

    According to an article in the NEJM, a Chinese woman who ate 1 to 1.5 kg (approximately 2 to 3 pounds) of raw bok choy daily developed severe hypothyroidism due to excessive ingestion of myrosinase.