How to Cook Greens

How to Cook Greens
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Dark green leafy vegetables are the most nutrient-dense foods on the planet. What’s the best way to prepare them?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“The main purpose of cooking vegetables is to make them more edible, palatable, and digestible.” The downside, though, is that “cooking may adversely affect the levels of nutrients, especially the heat-sensitive and water soluble ones.” But even if you boil greens for 10 minutes, the drop in antioxidant capacity, for example, which is a rough proxy for phytonutrient retention, isn’t that much. Yes, there’s a significant drop in each case—a 15 to 20 percent drop—but most of the antioxidant power is retained, even if you boiled lettuce for 10 minutes. The single nutrient that drops the most is probably vitamin C, but as you can see, collards start out so vitamin C-packed that even collard greens boiled for 10 minutes have twice as much vitamin C compared to even raw broccoli.

You can see the vitamin C in spinach really takes a hit. Even just blanching for five minutes can cut vitamin C levels more than half, with more than 90 percent dissolving away into the water after 15 minutes, though most of the beta carotene, which is fat soluble, tends to stay in the leaves. But just keeping it in a regular plastic bag, like you get in the produce aisle, can protect it. The refrigeration is important, though. Even in a bag, a hot day can wipe out nearly 50 percent. Not as bad as drying, though, which can wipe out up to 90 percent of the vitamin C, suggesting that something like kale chips may pale in comparison to fresh—though vitamin C is particularly sensitive. Other nutrients, like beta carotene, are less affected across the board.

Cooking by microwaving and steaming preserves the nutrition more than boiling, here measured in watercress. A little steaming or microwaving hardly has any effect compared to raw, though boiling even two minutes may cut antioxidant levels nearly in half. Watercress is a cruciferous vegetable, though—a cabbage- and broccoli-family vegetable—so it’s prized for its glucosinolate content, which turns into that magical cabbage compound sulforaphane. What does cooking do to it? Fresh is best, but steaming’s not bad, with microwaving coming in second, and then stir-frying and boiling at the bottom of the barrel. The glucosinolates in other cruciferous vegetables are also significantly affected by boiling. The researchers conclude that red cabbage is best consumed fresh, and look, not just in salads. As I talked about in How Not to Die, I always keep a red or purple cabbage in my crisper to cruciferize my meals, slicing off shreds and putting it on basically anything. But if you are going to cook it, steaming may be the best bet, “so as to retain the optimum benefits of the health-promoting compounds.”

Other nutrients we look to greens for are the eyesight-preserving nutrients like lutein, which I’ve talk about before, and folate, particularly important for women of child-bearing age; and vegetables are the main natural source. It’s been estimated that approximately half the folate is lost during cooking, which may be true for boiling broccoli, or stir-frying spinach or mustard greens. But the folate in stir-fried kale holds up better, only losing about a quarter, similar to steamed broccoli florets. But note that broccoli starts out so high that even boiled broccoli has more folate than raw spinach. But check out broccoli leaves. Not only do they start out with the highest levels, the levels actually go up a bit when you cook them. No one’s ever looked at the folate concentration in broccoli leaves, which ironically are commonly just cut off and thrown away, yet contribute great concentrations of this vitamin. Therefore, we should make sure to eat them.

Note they also compared thinly-sliced kale to kale just torn into larger pieces, to determine if a larger surface of exposure would promote greater losses of folate in kale. However, no effects were found, so slice away. Here, they just looked at stir-frying. What about the effect of other cooking methods on kale? There’s lots of studies on cooking cabbage and broccoli. However, very little information has been available on the queen of greens…until now.

First of all, fresh versus frozen. “The freezing process is generally regarded as destructive to antioxidant compounds.” One just assumes that frozen would have a lower antioxidant capacity compared to fresh, but kale breaks all the rules. The frozen kale showed a higher antioxidant capacity than fresh. And not just by a little; we’re talking 60 percent more. Wow! Okay, what happens when you cook it? If you start out normalizing the starting levels at 100 percent, blanching and steaming actually boost the antioxidant content, whereas microwaving or even boiling doesn’t seem to do much—so you can boil kale without losing out on its antioxidant punch. I told you kale’s a rule breaker.

But check out that blanching and steaming. Heat can disrupt the plant cell walls and all the little subcellular compartments, and spill out extra antioxidant compounds that may have been hiding. Now that’s usually counterbalanced by losses caused by high temperatures, but the kale compounds are looking pretty cruciferocious, and stood their ground.

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Image credit: pxhere. Image has been modified.

Motion graphics by Avocado Video

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“The main purpose of cooking vegetables is to make them more edible, palatable, and digestible.” The downside, though, is that “cooking may adversely affect the levels of nutrients, especially the heat-sensitive and water soluble ones.” But even if you boil greens for 10 minutes, the drop in antioxidant capacity, for example, which is a rough proxy for phytonutrient retention, isn’t that much. Yes, there’s a significant drop in each case—a 15 to 20 percent drop—but most of the antioxidant power is retained, even if you boiled lettuce for 10 minutes. The single nutrient that drops the most is probably vitamin C, but as you can see, collards start out so vitamin C-packed that even collard greens boiled for 10 minutes have twice as much vitamin C compared to even raw broccoli.

You can see the vitamin C in spinach really takes a hit. Even just blanching for five minutes can cut vitamin C levels more than half, with more than 90 percent dissolving away into the water after 15 minutes, though most of the beta carotene, which is fat soluble, tends to stay in the leaves. But just keeping it in a regular plastic bag, like you get in the produce aisle, can protect it. The refrigeration is important, though. Even in a bag, a hot day can wipe out nearly 50 percent. Not as bad as drying, though, which can wipe out up to 90 percent of the vitamin C, suggesting that something like kale chips may pale in comparison to fresh—though vitamin C is particularly sensitive. Other nutrients, like beta carotene, are less affected across the board.

Cooking by microwaving and steaming preserves the nutrition more than boiling, here measured in watercress. A little steaming or microwaving hardly has any effect compared to raw, though boiling even two minutes may cut antioxidant levels nearly in half. Watercress is a cruciferous vegetable, though—a cabbage- and broccoli-family vegetable—so it’s prized for its glucosinolate content, which turns into that magical cabbage compound sulforaphane. What does cooking do to it? Fresh is best, but steaming’s not bad, with microwaving coming in second, and then stir-frying and boiling at the bottom of the barrel. The glucosinolates in other cruciferous vegetables are also significantly affected by boiling. The researchers conclude that red cabbage is best consumed fresh, and look, not just in salads. As I talked about in How Not to Die, I always keep a red or purple cabbage in my crisper to cruciferize my meals, slicing off shreds and putting it on basically anything. But if you are going to cook it, steaming may be the best bet, “so as to retain the optimum benefits of the health-promoting compounds.”

Other nutrients we look to greens for are the eyesight-preserving nutrients like lutein, which I’ve talk about before, and folate, particularly important for women of child-bearing age; and vegetables are the main natural source. It’s been estimated that approximately half the folate is lost during cooking, which may be true for boiling broccoli, or stir-frying spinach or mustard greens. But the folate in stir-fried kale holds up better, only losing about a quarter, similar to steamed broccoli florets. But note that broccoli starts out so high that even boiled broccoli has more folate than raw spinach. But check out broccoli leaves. Not only do they start out with the highest levels, the levels actually go up a bit when you cook them. No one’s ever looked at the folate concentration in broccoli leaves, which ironically are commonly just cut off and thrown away, yet contribute great concentrations of this vitamin. Therefore, we should make sure to eat them.

Note they also compared thinly-sliced kale to kale just torn into larger pieces, to determine if a larger surface of exposure would promote greater losses of folate in kale. However, no effects were found, so slice away. Here, they just looked at stir-frying. What about the effect of other cooking methods on kale? There’s lots of studies on cooking cabbage and broccoli. However, very little information has been available on the queen of greens…until now.

First of all, fresh versus frozen. “The freezing process is generally regarded as destructive to antioxidant compounds.” One just assumes that frozen would have a lower antioxidant capacity compared to fresh, but kale breaks all the rules. The frozen kale showed a higher antioxidant capacity than fresh. And not just by a little; we’re talking 60 percent more. Wow! Okay, what happens when you cook it? If you start out normalizing the starting levels at 100 percent, blanching and steaming actually boost the antioxidant content, whereas microwaving or even boiling doesn’t seem to do much—so you can boil kale without losing out on its antioxidant punch. I told you kale’s a rule breaker.

But check out that blanching and steaming. Heat can disrupt the plant cell walls and all the little subcellular compartments, and spill out extra antioxidant compounds that may have been hiding. Now that’s usually counterbalanced by losses caused by high temperatures, but the kale compounds are looking pretty cruciferocious, and stood their ground.

Please consider volunteering to help out on the site.

Image credit: pxhere. Image has been modified.

Motion graphics by Avocado Video

Doctor's Note

I often get questions about how to prepare certain foods to maximize their benefits, so I love when I can bring you videos like this one and Best Way to Cook Vegetables. I have a few more on optimum cooking methods, too. Check out:

I mentioned microwaving: Are Microwaves Safe? And what about The Effects of Radiation Leaking from Microwave Ovens? Watch the video!

If you’re watching this, you probably know by now how important it is to eat greens everyday. But here are some videos for a refresher:

Just remember that anyone who eats cups a day (as they should!) of dark green leafy vegetables should probably stick to low-oxalate greens (i.e., basically any greens other than spinach, Swiss chard, and beet greens) to avoid the risk of kidney stones. For more on that see: Oxalates in Spinach and Kidney Stones: Should We Be Concerned? and Kidney Stones and Spinach, Chard, & Beet Greens: Don’t Eat Too Much

And to see how I cook my greens, check out: Does Pressure Cooking Preserve Nutrients? 

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

104 responses to “How to Cook Greens

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    1. When they refer to “frozen kale” are they referring to kale that has been blanched before freezing? This is an important question when considering buying frozen kale. Dr Greger has previously pointed out that commercially frozen vegetables are blanched before freezing. Please advise…

      1. Hi Kevin Costello, thanks for your question. Dr Greger in the video explains that. “The freezing process is generally regarded as destructive to antioxidant compounds.” One just assumes that frozen would have a lower antioxidant capacity compared to fresh, but kale breaks all the rules. The frozen kale showed a higher antioxidant capacity than fresh. And not just by a little; we’re talking 60 percent more.

      2. Kale can go into the freezer fresh ,which I prefer , but is bulky . You can cook it first and than freeze it , takes less room . Either way is good .

    2. Freezing kale also takes out the bitterness . In the Netherlands, kale is only harvested after the first frost , traditionally . It is chopped really small and cooked . We than stir it into mashed potato’s . Great with pickled gherkins .

  1. How about blending greens into a green smoothie? I have gotten into the habit of blending kale with other veggies in a water base to make a green smoothie. Have there been any studies on the loss of nutrients due to blending either fruits or veggies?

      1. Dr Cobalt, Thanks for the link to the green smoothies video. I watched all 3 of the related videos. I’m glad to see that the green smoothie routine is OK and does improve absorption of nutrients. I only blend fruits, berries, and vegetables, but not grains. As one of the other videos points out, blending grains can give an insulin spike. Thanks again for the link.

      2. AMAZING! Excellent science thank you dr cobalt. I was looking for that information for a few months. The 2 subsequent videos to the link you provide, goes ALL the way. Delighted with this last Dr Greger video and the 3 ones of 2015. I don’t understand how I missed that.
        So content I finally closed the gap.

    1. Hello Darwin,

      Blending greens in a smoothie is actually a great way to increase absorption of many nutrients, including carotenoids. This is because blending can help destroy the cell walls that have a bunch of nutrition trapped inside. Kale is a fantastic option because it is also low in oxalates, compared to spinach, which can reduce some mineral absorption.
      If you want to look further at topics such as weight gain/loss, oxalates, and so on, here’s a great video for you to watch: https://nutritionfacts.org/video/the-downside-of-green-smoothies/

      I hope this helps,

      Matt, Health Support

      1. This may be a two-edged sword since it will also presumably increase the absorption of heavy metals in vegetables.

        Reports from some countries suggest that heavy metal contamination commonly exceeds safe levels. Blending would only exacerbate the problem presumably.

        One would hope that produce sold in Western countries, including imported produce, is safer but who knows. Even home grown produce may not be safe depending on your garden soil and local atmospheric pollution levels.

        As a general principle, avoiding heavily processed foods like smoothies may be a good idea especially for people trying to lose weight since I understand that blending increases calorie aborption from food as well as mineral etc absorption.

        1. Advising against smoothies because of alleged heavy metal contamination strikes me as misguided. Speculating that smoothies should be avoided by people trying to lose weight seems similarly misguided to me. A whole food plant based smoothie is not a food from which a typical person is going to be able to maintain an obese state.

          1. Josh

            If you read what I wrote, you will see that I did not advise against consuming smoothies. I simply suggested that that there MAY be some negatives as well as positives. And that whole foods may be preferable on general principle. Not quite the same thing.

            As for the weight issue, your opinion about whole plant food smoothies is interesting but, in complete contradiction, the Livestrong website suggests fruit smoothies for weight gain. I’d post the lnk but my laptop/browser now refuse to do copy paste actions. However, you can Google it if you wish and as well you can search for Dr Greger’s video on the downsides of green smoothies which also makes the point that smoothies can increase calorie intake.

            1. I think personal experience can speak loudest in this regard. I lost weight having almost nothing but smoothies for a time in the past. I also never felt unsatisfied as reports in one of Dr. Greger’s videos states which was due to drinking them quickly so he suggested sipping them slowly. I used to guzzle them as quickly as I could (pretty much because the ones I made, I did not make taste so good back in the day) and I would feel very full for a long time–I suspect due to getting so many nutrients from them. I know it can help get calories in but it just doesn’t seem to pack on the pounds and in my experience causes weight loss if necessary. Maybe it’s more impactful in regards to weight gain for people who need to gain weight due to insufficient calorie consumption.

        2. I switched to green smoothies as my primary dinner for a few months and continuously lost weight during this time, even though I was eating as much as I wanted. I always had steady weight near ideal and never had issues with weight loss before. I did not really want to loose weight so tried adding significant extra calories at other meals using nuts, peanut butter, sweet potato, and others, but could not stop the continued drop in weight. Finally I just stopped the green smoothies, and did veg and bean stews and pan steamed mixed veg over varied grains and the weight came back to normal and stabilized, even without the extra calories.

          My green smoothie recipe was designed to be maximally anti-cancer and consisted of mixed and varied (2 or 3) different cruciferous for isothiocyanate synergism, alliums like green onions or red onion, a whole clove of elephant garlic pre-chopped and let to sit for 10min, 1 cup berries (varied), one tbsp of heat treated fresh turmeric root, 2 tsp cumin powder, a medium avocado, a banana(just for taste), Iodine drops to 100% RDA, and several ice cubs.

          Now I just have the green smoothie every few days, instead of every day, and no more weight loss problem.

          1. Scott, I don’t know how a banana could help improve the flavor of blended garlic and onions, haha, but I’m sure it helped. Curious, how did you heat treat the turmeric? Thanks!

          2. Correction: 1/2 tsp cumin, not 2 tsp. Yikes.

            The turmeric root I grate first and then simmer in a small amount of water for ~5-10min.

        3. Mr Fumbles, that seems a bit over-worrying to me, not to say that you don’t have a point. Personally, I’ve been blending greens and other plant foods for consecutive years almost on a daily basis and I have had zero issues with heavy metals, having had my blood tested for them once during that time a few years ago. I feel amazing after my smoothies. But that might be something to think about for those who are only able to get their produce from extremely polluted parts of the world.
          Couldn’t also be suggested that perhaps the enhanced bioavailability of the antioxidants and other nutrients could negate any potentially enhanced bioavailability of existing heavy metals?

          1. Couldn’t also be suggested that perhaps the enhanced bioavailability of the antioxidants and other nutrients could negate any potentially enhanced bioavailability of existing heavy metals?
            ———————————————————————————–
            THAT’s the point I’ve been waiting for someone to make.

            I don’t eat perfectly all the time but I compensate by over-eating things that are perfect. I really wish Dr. Greger would address some of these balancing factors in future videos instead of just saying “This is good” or “That is bad.”

            He could do a lot of good by giving us sinner/saints a way to counteract our bad habits.

            1. His dining by traffic light video kind of does that. Also, in regards to oil, in one interview on youtube he was asked if he HAD to choose a healthier oil then what would he suggest, and he emphasized if pressed, he would say there’s healthier oils like extra virgin olive oil compared to other more processed oils like sunflower, etc. And pointed out that some highly processed oils can actually create tiny amounts of transfats but very, very tiny. Obviously hydrogenated have lots of trans fats. And for someone like me who will always use some amount of oil, I find that kind of information helpful.

              Another thing to consider when you’re eating something less than perfect, is to remember that our antioxidants can get used up quickly under some circumstances and the fact that we need them with all our meals because that’s just part of the process of digestion–we evolved to eat antioxidant-rich foods. So it would be a good idea to always include antioxidants such as some berries or spices or something, even if you’re eating like crap and maybe especially so.

              1. Also, in regards to oil, in one interview on youtube he was asked if he HAD to choose a healthier oil then what would he suggest, and he emphasized if pressed, he would say there’s healthier oils like extra virgin olive oil compared to other more processed oils like sunflower, etc. And pointed out that some highly processed oils can actually create tiny amounts of transfats but very, very tiny. Obviously hydrogenated have lots of trans fats. And for someone like me who will always use some amount of oil, I find that kind of information helpful.
                ——————————————————————
                Yes, that’s the kind of information that would be helpful. If at the end of each video pointing out the harmful eating practices he could also tell of ways to overcome that harm to some degree, that could help a lot of people who just cannot/will not adopt a complete turn-a-bout in their way of eating.

                I get it that the message is to change your eating lifestyle, change your life… but I think the bigger picture should be “let’s at least make some changes to get you on the road to bigger and better ones.” WFPB Disciples will not adopt the shortcut.

                Just one man’s opinion.

          2. S

            Yes, you may be right. I even own two blenders myself (but only use them occasionally).

            However, I don’t know for sure either way. Living in the Philippines for most of the year, though, there’s probably a higher chance that my fruit and vegetables may be contaminated than would be the case for you. And I am not confident that the belief that the good stuff will render the bad stuff harmless is correct. That might be true or it might just be wishful thinking. It reminds me of the Scandinavian study that showed that people eating large amounts of meat had higher mortality even when they ate large amounts of fruit and vegetables.

  2. The bottom line here seems to be that the best way to cook greens is the way that you are most likely to eat them rather than choosing something else.

      1. Diet is like exercise. The more it is done, the more the benefits are noticeable in body shape and medical lab tests.

        If I backslide I do not beat myself up and it makes it easier to slide back into healthy habits that become daily routine.

    1. Agreed, and how you enjoy them. And mixing it up, eating both raw and cooked vegetables. There’s other videos on this site showing benefits to cooked vegetables with certain nutrients becoming more bioavailable and increasing bile binding potential of certain vegetables. Then there’s the whole cooked then cooled (ok to heat again) starch benefits. And cooked beans have more benefits than sprouted in a lot of ways and vise versa. Variety is key in getting the most benefits.
      There’s also the video showing how women who did all raw diets went into early menopause, possibly due to the amount of energy it took to digest a 100% raw diet.
      And even though kale chips might have a lot vitamin c loss, they’re still such an awesome snack and beat the hell out of other chips.

  3. I know Dr. Greger is coming out with some videos on intermittent fasting but I was wondering if he could please spill the beans before the December release date on:
    1) Eating one meal a day. If I eat my 2 pounds of greens does that stop the other nutrients I eat later in the meal from being absorbed? I know there are some rat studies on stress to the pancreas, but a rat’s metabolism is so much faster than ours, I don’t think that we can learn out so easily.
    2) Is it better to work out before we eat or after?

    1. YGR,
      Dr. Longo, who did a lot of the original research on calorie restriction, etc., states that daily fasting for more than 14 hrs per day doubles the risk of gallstones, something I would not risk. Check out his book TheLongevity Diet or some of his YouTube interviews. Instead of water fasting, he recommends his fasting-mimicking diet, supposedly safer and just as effective.

      https://www.youtube.com/watch?v=xvx38rYU9yE

        1. I was very disappointed to see this reply. To me it runs against the whole philosphy of NutritionFacts.org! If you disagree, where is your scientific data? Then, to make it worse, you impugn the honesty of another researcher with no basis offered. I suppose that any regular reader here will give this comment the attention it deserves, that is, none. I could not resist commenting though I probably should have ignored this also.

        2. Do you have anything whatsoever to back up your claim what he says is untrue?

          An increase in gallstone formation risk is commonly recognized, e.g.
          https://www.cedars-sinai.org/health-library/diseases-and-conditions/g/gallstones.html

          Health issues that may raise your risk for gallstones include:

          – Obesity. This is a major risk factor, mainly for women.
          – Estrogen. Women may have extra estrogen from pregnancy, hormone replacement therapy, or birth control pills. This seems to raise cholesterol levels in bile and slow down gallbladder movement. Both can lead to gallstones.
          – Diet. Eating a high-fat, high-cholesterol, or low-fiber diet raises your risk. They lead to more cholesterol in the bile and reduced gallbladder emptying.
          – Cholesterol-lowering medicines. These medicines can increase the amount of cholesterol in bile.
          – Diabetes. People with diabetes often have high levels of fatty acids (triglycerides). This raises the risk for gallstones.
          – Very fast weight loss. As the body processes fat during very fast weight loss, the liver sends out extra cholesterol into bile.
          – Not eating for a few days (prolonged fasting). Fasting slows down gallbladder movement. Over time, your bile has too much cholesterol.
          – Cf.

          https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1419405/

          It would be nice to learn otherwise but your post provides not bancking.

        3. It is my understanding that Valter Longo donates all the money to charity allotted to him from the sale of the fasting mimicking meals. I think USC also may have a financial interest, but I’m not sure. Fraud?… more like Luminary in my view.

  4. I don’t boil greens, or any veggies, really. But I do steam them, often on the stove top. Then I save the steam water in the fridge to use in cooking beans, grains, soups, stews, etc. I do that for flavor, as I have no idea what happens to whatever nutrients might be in that water during cooking (though I use an Instant Pot these days).

    I also microwave some veggies, especially winter squash, because it’s so easy and quick.

    I don’t stir fry much; I don’t know how to do it without oil. Plus, I’m lazy. Maybe that’s just as well. But I have a little electric grill with ceramic plates that I use to grill summer veggies (especially sweet peppers and summer squash), no oil required; they are so good! I wonder how that affects their nutrients?

    1. Dr. J, all it takes to stir fry with no oil is water sautéing, you just add a little water instead of oil and add additional water as you cook as needed. I use a stainless steel pan.

    1. Yes I would like to know about pressure cooking too because that is the way I cook my Kale and Collard greens. It is quick and they come out tender.

  5. Question: Is it okay to drink the pot liquor? We love boiling power greens in water with Kirkland’s no salt seasoning. We eat the greens then slurp down the broth. It’s delicious but is it safe/healthy?

    1. Poison. Please pass it down the table to me, I will take care of it for you.
      In fact anyone else, kindly send it to P.O. Box…..

      Thanks for that recipe idea, going to Costco today for both ingredients.

      1. When I was a little boy (80 years ago) I would always drink the broth left from boiling spinach. I guess
        it was the right thing to do.

    2. That’s a fantastic idea to make sure you’re missing out on any of the nutrition in the greens! And you’re right… It is often delicious!

      Keep it up,
      Matt, Health Support

  6. What studies have focused on the baking of vegetables? I love baked broccoli, carrots, sweet potatoes, yams, brussel sprouts, and cauliflower. And how does baking compare to the other cooking methods you noted in the video below? Many thanks.

  7. I thought that in a previous video, it was shown that if you cook cruciferous veggies, you kill off an enzyme that’s needed to create an anticancer chemical.

    1. Hello Steve,

      You’re right! It’s a good idea to chop cruciferous veggies about 45 minutes ahead to time to ensure maximum production of glucosinolates (sulforaphane). In this video, it is stated that if you lightly steam cruciferous veggies for a short time, then you can still get some glucosinolates. But to maximize your nutrition, chop them first or add some mustard seed powder after cooking.

      I hope this helps,
      Matt, Health Support

      https://nutritionfacts.org/video/second-strategy-to-cooking-broccoli/

  8. I wonder what happens if you preserve these greens – like cabbage or other sturdy vegetables – in brine like sauerkraut. Do they lose anything then? Kale kraut? Anyone tried it?

    1. I second Nel’s question. I’m a kraut fan–the homemade (fermented) variety, not the “add vinegar and salt and boil to hell” type. I wonder how the different nutrients react to fermentation as compared to various methods of cooking.

      I *have* added small amount of kale to my mostly cabbage kraut, but I’ve not attempted kraut made from mostly kale. I found one recipe…

      https://www.culturesforhealth.com/learn/recipe/lacto-fermentation-recipes/hearty-leafy-green-kraut/

    2. Would also like to know about preserving in brine. I recently bought some garlic cloves in brine. They are really tender… just wish I knew if they were still garlicky.

    3. Studies from eg China and Korea have found a 50% increased risk of gastric cancer with regular pickled vegetable consumption. This is usually attributed to the high salt/sodium content.

  9. WAAIIT so my frozen berries don’t contain the antioxidants in fresh berries? But basically ALL the berries I eat are frozen :-(

    1. Yes May, I saw that too! Mountains of fresh berries are sitting there rotting in stores because og high prices… same with kale, chard, celery… The only reasonable priced berries are frozen on sale. Guess they are a waste of money too!

      1. May and Barb, my understanding is that, unlike veggies, fruit are not blanched before they are frozen (it would make them mushy), so frozen berries should retain a lot of their initial nutrition. I’ve read, too, that freezing even increases the antioxidant levels in blueberries. So I think we’re okay—I eat a lot of frozen blueberries and strawberries on my morning oatmeal. Serious yums!

        1. Maureen, thank you so much for that reassuring note!

          BTW, as an experiment this past fall i washed curly kale and froze it. No blanching. I threw it into soups over the winter. It was great, couldn’t tell it was ever frozen.

          1. That matches my experience with kale– the taste not only survives freezing, but doesn’t taste even slightly “frozen” after one week or more wrapped in only a film shopping bag. (It isn’t neglected much longer than that).

            Kale is a daily requirement for me, due to its nutritional benefit of lutein and zeaxanthin to the brain and retina, not to mention all its antioxidants.

          2. Barb, that matches my experience with frozen kale– no effect on taste, after more than one week in the deep freeze.

            Kale becomes a daily requirement due to its massive contribution of antioxidants, which freezing apparently further liberates.

            Kale’s heroic portion of lutein and zeaxanthin are reassuring protection for retinal and brain function.

    2. But basically ALL the berries I eat are frozen :-(
      ——————————————————————
      Just in case, I simply eat more of them. ‘-)

  10. More data is needed here. Boiling study does not seem to take into account that many nutrients may be leeching into the water used to cook the greens. Where I come from people drink that ‘pot liquor’ as it is considered the best part. Nutrients in a water suspension are also more absorbable than those still inside solid foods that often do not get chewed enough.

    On a side note, I braise my greens. Most people I know do.

  11. Wonderful video! Answers a lot of my questions about cooking veggies. I usually just lightly steam them all, except greens which I also like raw. But sometimes it’s easier, less time consuming, to eat a lot of greens if they are cooked. Have collards, kale, purple cabbage and spinach prepped to use, great timing for this video.
    Thank you so much Dr. Gregor!

  12. Okay, when you are talking about broccoli leaves, my question would be: Does that mean broccoli microgreens?

    I have been looking at broccoli microgreens at Whole Foods and I keep wondering where they fit into the equation.

    1. Hi Deb,
      I recently read that brassicas can be eaten top to bottom, except they didn’t mention the roots. I was so delighted to find out that I could enjoy the entire plant rather than chopping off this that and the other thing.

      I just did an Internet search and there are plenty of pictures of the leaves. The leaves on the brassicas that I know of, the brussels sprouts and broccoli at least, can be quite large and taste fine. I even use them as a substitute for flat breads to make wraps. Besides smoothies, using them for wraps is another easy way to use them raw if you’re OK with them being a little more sturdy. I’m fine with the harder parts, I just chop them up and include them in the ingredients inside the wrap.

      Hope that helps.
      Best wishes!!

    2. My CSA has broccoli leaves during a certain part of the year. They are huge–like the kale leaves I get there, too, and come in bunches–just like kale. I thought they must be healthy and have been getting them whenever they have them….

  13. I love broccoli and brussel sprout greens. They are absolutely delicious. Don’t throw those leaves out when growing those plants! I slice them thinly and stir-fry them in water with a touch of garlic and mustard powders.

  14. We hear frequently that green leafy vegetables are the most nutrient dense. Considering that they weigh almost nothing, if they have any nutrient value at all, it would have to be pretty dense!

    So, how is this nutrient content “normalized” to allow proper comparison? By weight? I would be hard pressed to eat enough lettuce to ompare by weight to a serving of, say, broccoli or cabbage. The notion of serving size has major pitfalls, as well – so what’s up?

  15. Wish they had included dried kale nutrition. I just finished a bowl of no fat refried beans (I know, sounds like an oxymoron) with added kale powder, Ro-tel diced tomatoes and green chili’s (pkgd in glass) guacamole salsa, hemp protein powder and hemp, walnut, and MCT oil.

    I’m sure the kale loses some of its strength but if it’s a lot, I will add Moringa powder instead of kale going forward.

    1. Yes, I would like to know dried kale nutrition, too.

      I do eat some fresh kale, but I love kale chips.

      I am trying to keep going with these fresh veggies, but, boy, they are all expensive.

      I am trying to remember whether almond milk wrecks the nutrition of blueberries.

      I bought some almond milk yogurt and packed it with blueberries and I loved it.

      I loved blueberries.

      Now, if only they could just please still have some of the brain benefits that way.

      1. I bought some almond milk yogurt and packed it with blueberries and I loved it.
        ——————————————————————————————————–
        I’m going on the assumption that almond milk is alright as it is pretty much just squeezed almonds and water. I add almond milk to a bowl of frozen blueberries and frozen cherries. Makes a good ice cream substitute as it becomes like a slushy.

        But another summer snack that refreshes is a couple of packets of gelatin powder with a small spoon of Moringa Oleifera, magnesium powder, maca powder, ashwagandha powder and even some LL brewer’s yeast if I remember that… (I forgot it in the batch I made just this morning.)

        The gelatin I bought on sale (for mixing vodka with) is sweet so these additions aren’t making the gelatin in-edible. Besides, I also add a lot of frozen blueberries and frozen cherries to the mix along with some Just Tart Cherry juice and a little beet root juice to get the color back to something more jello-like.

          1. Just had a passing-the-fridge spoon of the gelatin concoction and the flushing of my face reminded me I also added some niacin powder to the gelatin mix… and my taste buds reminded me I added some cinnamon as well. ‘-)

      2. By any chance is there a link for the video which discusses drinking soy milk with blueberries? I know dairy stops absorption but I seem to remember a video mentioning that soy milk does, too. However, I cannot find it.

        1. I think it was a tea and soymilk video.

          Okay, here is the blueberries with dairy yogurt. Watched it again and the antioxidants going down worse than before you ate any berries is the part that becomes scary. I remembered that there wasn’t a benefit, but there was a mega-drop with regular dairy yogurt. Yikes.

          https://nutritionfacts.org/video/benefits-of-blueberries-for-blood-pressure-may-be-blocked-by-yogurt/

          I found the soymilk one.

          https://nutritionfacts.org/video/soymilk-suppression/

    1. Although some Vit C is lost due to high heat of boiling, it appears that some of the remaining Vit. C leaches out into the water. I could not find a research study to detail how much Vitamin C might be available in the water remaining. However most authorities encourage using that water for soups (or simply drinking) to obtain what nutrients remain. Here’s what the Harvard Medical School Family Health Guide suggests for salvaging the water after draining the vegetables. “Pour the water into a plastic storage container and use it for soups, sauces or your favorite gravy recipe. If you are not going to use the water right away, cover the container and place it in the refrigerator until you need it. Nutrient Content
      Just as fresh vegetables lose their nutrient content over time, so will the nutrient-rich vegetable water. Left to stand at room temperature, light and oxygen will eventually cause evaporation of the water and the dissipation of the dissolved vitamins. Storing the vegetable water in the refrigerator prolongs nutrient retention.” Freezing is also recommended, until you make your next batch of healthy soup! Hope that helps.

      1. I stopped reusing cooking water because I feel that it might have started causing swelling in my hand. It might bring about oedema in people.

  16. I have a dehydrator, and like to eat a lot of dried kale, as kale chips.
    So I don’t mind that the vitamin C is lower, since you can get that from a lot of other sources.
    But I’ve been curious about how other nutrients compare, with dried vs steamed vs raw?

    1. As you are aware,steaming involves loss of nutrients due to use of water as well as due to the higher heat. I was able to find this study that should be help answer your question:
      Retention of nutrients in green leafy vegetables on dehydration https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3722389/
      “Dehydration seems to have little effect on the proximate, mineral and antinutrient content of the GLV (Green leafy vegetables) Among the vitamins, retention of ascorbic acid was 1–14%, thiamine 22–71%, total carotene 49–73% and β—carotene 20–69% respectively, of their initial content. Dialyzable iron and calcium in the fresh vegetables ranged between 0.21–3.5 mg and 15.36–81.33 mg/100 g respectively, which reduced to 0.05–0.53 mg and 6.94–58.15 mg/100 g on dehydration. Dehydration seems to be the simplest convenient technology for preserving these sources of micronutrients,”

      So yes, you are correct in recognizing you’ll lose Vit C when you dehydrate your kale, but you are still obtaining some Vit C and you’re obtaining other nutrients. As someone who also likes my kale chips, I found this study to be reassuring and I’ll continue enjoying my kale chips as I hope you do, knowing we’re obtaining perhaps less Vit C but lots of other nutrients. Perhaps not as much as in the raw form, but if we eat more GLVs we’re still ahead!

      1. Yes, thanks for the link to that great article! In the study, they blanched the green first…while I’ve been starting with raw kale, and have been trying to use a lower drying temperature, to preserve more nutrients, since that seems to be a factor… .Really enjoy the dehydrator, and it sure saves a lot, looking at the price of kale chips in the store! Some other good greens to dehydrate are, mustard greens, they’re naturally spicy

  17. Hello, I tried registering for your webinar on intermittent fasting announced today. However, the link in the email you sent goes to the old webinar on cannabis completed in 2017.
    Could you please re-send the correct link in the email?
    Thanks.
    Andrea

  18. What macronutrient ratios are best to eat in terms of time of day? Wondering whether there’s a benefit to eating different ratios depending on time of day or not.

  19. About soaking nuts and seeds, can you use other salts besides sodium chloride? How long can you store the soaked nuts before consuming them if you don’t dehydrate them?

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