Sometimes the Enzyme Myth is True

Sometimes the Enzyme Myth is True
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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.

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You’ll hear folks in the 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’re 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 sulforaphane is one of them.

One of our most powerful phytonutrients, it is formed by an enzyme in broccoli. You cut or chew or chop up broccoli or broccoli sprouts, and the enzyme is released and it 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 shown detectable sulforaphane levels in the blood and urine of people 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 sulforaphane for us. And the way they figured this out is that you incubate cooked vegetable juice with fresh human feces and voila! Sulforaphane is born.

Not as much, though. To get the same amount of benefit in a cup of raw broccoli, you’d have to eat ten cups of cooked broccoli. So, I encourage people to try to eat their broccoli raw, or, alternatively, 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 broccoli soup, put it in the blender raw, blend, 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 pre-chopped 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 summarizing the available evidence.

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.

Please consider volunteering to help out on the site.

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

You’ll hear folks in the 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’re 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 sulforaphane is one of them.

One of our most powerful phytonutrients, it is formed by an enzyme in broccoli. You cut or chew or chop up broccoli or broccoli sprouts, and the enzyme is released and it 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 shown detectable sulforaphane levels in the blood and urine of people 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 sulforaphane for us. And the way they figured this out is that you incubate cooked vegetable juice with fresh human feces and voila! Sulforaphane is born.

Not as much, though. To get the same amount of benefit in a cup of raw broccoli, you’d have to eat ten cups of cooked broccoli. So, I encourage people to try to eat their broccoli raw, or, alternatively, 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 broccoli soup, put it in the blender raw, blend, 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 pre-chopped 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 summarizing the available evidence.

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.

Please consider volunteering to help out on the site.

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

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.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

47 responses to “Sometimes the Enzyme Myth is True

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  1. 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.




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  2. 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!




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  3. 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!




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  4. 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!




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  5. 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.




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




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  6. 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.




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    1. 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.




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  7. 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




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  8. 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.




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  9. 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!




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    1. 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.




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  10. 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?




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  11. 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.




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  12. 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.




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  13. 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?




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    1. 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.




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      1. 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.




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  14. 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.




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  15. 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?




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    1. Hi Shaun!

      If you purchase raw nuts it is best to soak then in water overnight. Soaking helps to get rid of phytic acid and neutralizing enzyme inhibitors enabling easy digestion and elevating absorption of vitamins and other nutrients in the nuts.

      Otherwise most of the nuts in the store are roasted so you dont eat to soak them. The only thing they dont have enzymes. It is good to eat foods high in enzymes as much as possible in my opinion.

      Viktoriya
      https://viktoriyaandoksana.com/




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  16. 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?




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  17. In a Q&A dated Feb 2 Dr Greger briefly answers a question about taking digestive enzymes. He states our pancreas makes all we need. Right and wrong. There is more to this. Yes Our pancreatic enzymes are secreted but they are secreted in the duodenum which has a pH of 6.3. This is where they are active (except for one of the amylases in the mouth). Unfortunately, this is after our food has left the stomach. Here’s the potential problem: as we begin eating the stomach divides itself into upper and lower collecting areas. The cardiac portion, or upper portion, and a lower smaller area where stomach acid will be produced. The stomach holds the food in the upper section for up to an hour HOPING the enzymes that came with the food liquify the food before it drops it into the lower stomach where the acid finishes the protein peptide/ poly peptide conversion. There are in essence, multiple form of each enzyme in raw food. Example: Proteases, Amylases, Cellulases, etc each active in different pH’s from 2 to 12. The enzymes our pancreas produces are only active in 6.3 pH. If there are no enzymes in the food, the body must compensate. When we first start eating, our stomach pH is 1 or 2. As we add more and more food the pH of our stomach rises to as high as 6.4. After we eat a meal of cooked food we can measure the following: a high white cell count in the blood: the immune system is being used to help digest the cooked food. After years of eating mostly cooked food we see that the pancreas enlarges to 3 times its normal size. The body steals proteins and other metabolic enzymes to compensate for the lack of enzymes in our food at the beginning of our meal. The body does not make some of the enzymes found in food such as cellulase, an enzyme for digesting fibre. The lack of this enzyme causes gas and bloating. This enzyme is also the enemy of candida.
    If you are going to choose a digestive enzyme, choose one with NO animal enzymes (unless your pancreas is not functioning well). Choose one with only plant enzymes to replace the ones you just cooked out of your food.
    There are also metabolic enzymes in raw food: SOD, Catalase etc These are not food in cooked food. You can Help your pancreas and your immune system and protein conversions by taking plant based enzymes with each meal of cooked food.

    Enzyme Deficiencies can be created and passed on from one generation to the other because of the family diet. Example: deficiency in amylases can result in asthma and/or eczema ( note the improvement when this enzyme family is supplied) Deficiency in lipases can result in psoriasis. (again not the improvement in this condition when these enzymes are supplemented.

    Once again note measurements in pancreas size, immune response and amino acid stealing in people who eat mostly cooked food. Some references can be found in Dr Howell’s work. Also check out the Loomis Institute. Enzyme therapies are now being used in our local children’s hospital.




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    1. Dr Howell’s research on food based enzymes was challenged by the science community. The took measurements of the general population in the three areas he researched: pancreas size, immune response after eating of cooked food, and the stealing of amino acids and metabolic enzymes to compensate for the lack of enzymes in the diet and concluded it was “normal “because it was found in everyone they tested. They missed his message/warning completely.




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  18. Though there are people who can’t eat raw vegetables and fruits. I recently learned about Oral Allergy Syndrome, which is an allergic reaction to eating raw fruits and vegetables, where symptoms include tingling mouths and itchy throats. It’s cause by a reaction to the same (or similar) proteins that are in pollen, and most often develops in adults. Cooking denatures these proteins, which is how these folks can eat their veggies and fruits. About 40% of those with pollen allergies are estimated to eventually develop OAS. It sometimes, though rarely, becomes life threatening. And not all sufferers are allergic to all vegetables and fruits; there are tables listing the vegetables and fruits most likely to cause an allergic reaction, depending on what type of pollen an individual is allergic to. But these aren’t infallible. And who would want to test these all out? This condition is apparently missed by many MDs.




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