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Sometimes the Enzyme Myth Is True

There are a few examples of plant enzymes having physiologically relevant impacts on the human diet, and the formation of sulforaphane in broccoli is one of them.

March 20, 2012 |
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Sometimes the Enzyme Myth Is True, 5.0 out of 5 based on 2 ratings

Sources Cited

Vermeulen M, Klöpping-Ketelaars IW, van den Berg R, Vaes WH. Bioavailability and kinetics of sulforaphane in humans after consumption of cooked versus raw broccoli. J Agric Food Chem. 2008 Nov 26;56(22):10505-9.

Getahun SM, Chung FL. Conversion of glucosinolates to isothiocyanates in humans after ingestion of cooked watercress. Cancer Epidemiol Biomarkers Prev. 1999 May;8(5):447-51.

Acknowledgements

Images thanks to Jawahar Swaminathan via Wikimedia commons, Whole Foods, and cassandrapw.

Transcript

You’ll hear folks in raw food community waxing poetic about enzymes, the importance of preserving the activities of plant enzymes, which are destroyed by cooking. Skeptics, on the other hand, indignantly assert that we have no use for plant enzymes, since we are animals and make all the enzymes we need. Well, both sides are wrong. There are two known examples of plant enzymes serving physiologically useful functions, and the production of sulphuraphane is one of them.
One of our most powerful phytonutrients, it is formed by an enzyme in broccoli. You cut or chew or chop raw broccoli, or broccoli sprouts, and the enzyme is released and gets to work making us a big batch of phytonutrient goodness.
Cooking inactivates the enzyme, though, so steamed broccoli doesn’t have any. So why have experiments show detectable sulphuraphane levels in the blood and urine of people who eating only cooked broccoli? Now I’m really confused. Were they sneaking raw broccoli on the side?
No! (how cool is this?) Good bacteria that reside in our gut have the raw broccoli enzyme too! So as soon as the cooked broccoli gets down there, the bacteria makes sulphuraphane for you. And the way they figured this out is that you incubate cooked vegetable juice with fresh human feces and whallah, sulfuraphane was born.
Not as much though. To get the same amount of benefit in a cup of raw broccoli you’d have to eat 10 cups of cooked broccoli, so I encourage people to try to eat their broccoli raw or, alternately, chop the broccoli up first raw, wait 40 minutes for the enzyme to do its business and then you can cook the heck out of it because the enzyme’s job is already done.. So the next time you want to make like broccoli soup put it in the blender raw, blend, then wait, then cook. Safer too, since you’re not trying to blend hot liquids at the end.
Or if you don’t want to wait, you know those prepackaged bags of prechopped broccoli in the produce aisle? More expensive, but more convenient, and maybe even healthier, because it’s been building up anticarcinogens the whole time in the store.
For more on raw food controversies, I encourage everyone to go to their local library and check out Davis and Melina’s Becoming Raw which does the best job to date of summing up the available science on the matter.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by veganmontreal.

To help out on the site please email volunteer@nutritionfacts.org

Dr. Michael Greger

Doctor's Note

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.

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

  • http://nutritionfacts.org/members/mgreger/ 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.

  • http://nutritionfacts.org/members/thea/ 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!

  • http://nutritionfacts.org/members/getskinnygovegan/ 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!

  • http://nutritionfacts.org/members/lowfatveganchef/ 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 http://www.LowFatVeganChef.com

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

  • http://nutritionfacts.org/members/elvin/ 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 http://nutritionfacts.org/videos/raw-vs-cooked-broccoli-2/ 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.

  • http://nutritionfacts.org/members/elvin/ 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.

  • http://nutritionfacts.org/members/vegan2u/ 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 (http://bit.ly/GE7Wef) (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

  • http://nutritionfacts.org/members/georgei/ 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.

  • http://nutritionfacts.org/members/happyherself/ 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!

  • http://nutritionfacts.org/members/TanTruong/ Tan Truong

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

  • http://nutritionfacts.org/members/deana209/ 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.

      • http://nutritionfacts.org/ Michael Greger M.D.

        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.

  • http://www.facebook.com/ilan.djivre Ilan Djivre

    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)

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