Green Smoothies

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Are green smoothies better for you?

What about green smoothies? I blend apples, bananas, blueberries and spinach.

Heidi Woodruff / Originally asked on Best fruit juice

Answer:

I’m a huge green smoothie fan! You’re taking the healthiest thing on the planet (dark green leafy vegetables) and releasing all that nutrition (you could never really chew that well). In fact I just wrote the foreword for the Complete Idiot’s Guide to Green Smoothies, which will be out May 2012.

I’m currently compiling all the data in the scientific literature on the health effects of green smoothie consumption (for example there was a promising experimental trial recently performed in the UK). So stay tuned for a smoothie video in the 2013 batch I’m currently working on. Make sure you’re subscribed so you don’t miss it!

Image credit: little blue hen / Flickr

Discuss

Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.


43 responses to “Are green smoothies better for you?

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  1. One more comment I’m hoping you’ll address with green smoothies: I went to a talk with Caldwell Esselstyn. He is against smoothies for two reasons. When the fruit is blended, the fructose is separated from the fiber and that fructose is very damaging to the liver. Also, without chewing the greens, saliva is greatly reduced, which greatly reduces the transformation of nitrites to nitrates to nitric oxide, which helps the endothelium.

    1. I am also curious to know how Dr. Greger feels about this idea. I love my post-workout smoothies, but is fructose overload something we should be concerned about? Are there any studies out there to back this up?

    2. Im curious too about the green smoothies..i just blended kale, oatmeal, almonds, and a banana. it seems healthy to me. And I know its waaaay more healthy in the end that eating a burger right now…woo woo!

  2. Hello,

    I have a question regarding oxalate in green smoothies. I have read a few pros and cons regarding the oxalate in green smoothies and now I’m at a lost. Can you please let me know if green smoothies are a huge negative in a healthy lifestyle? I would greatly appreciate your response. Thank you!

    1. Every leafy green has a different built-in component, such as oxalate, etc., which discourages insects, caterpillars, etc., from munching on it. Each leafy green also has slightly different nutrients. The answer is to rotate the greens you put in your smoothies or eat in other ways on a daily basis. I use spinach powder, kale powder and a powder mixture that has several grasses (Amazing Grass ORAC Green SuperFood purchased on Amazon). When this grass powder is gone, I will probably purchase one that doesn’t have as many ingredients. I also freeze bags of spinach and kale if I find them on sale and throw the frozen greens into the smoothie. If you like romaine in your salads, or cook mustard greens, ect., you can put those greens in your smoothies occasionally to change it up. Of course, some greens taste much better than others. For the strong greens, blend your smoothie, then add the raw chopped greens last and don’t blend too long. If the smoothie makes you gag, throw it out and use less greens until your body gets accustomed to them.

      It is a good idea to eat your green smoothies one mouthful at a time, mixing your saliva in. As for me, the best way I am going to get enough oatmeal, leafy greens and fruit antioxidants into my diet is with a morning smoothie.

  3. Does blending vegetables give you more antioxidants because more (over just chewing) of the cells get broken or do you get less antioxidants because the salivary juices are less blended with the vegetables?

    1. You may be exposed to more of the nutrients indeed. I also posted above about the satiation concern. “The fibers are destroyed in a sense that you are no longer satiated as
      much. for example, a whole apple can fill you up more then a blended
      apple. This can be an issue for people who are overweight and do not
      want to consume excess sugar calories. Other than that, the fiber
      content itself is not diminished and you still get the benefits.”

      1. To this, I’do like to add that a smoothie is a food and, as a food, it has to be eaten with a spoon and not drinken with a staw on the go. Sit down and take the time to chew and enjoy it, and it will fill you up. To help, you may want to add some chunks of fruits…… after the blending!

  4. heard some “expert” (Dr. Robert Lustig, the sugar guy) say that blending fruits/veggies destroys the fibers so that you do not get the insoluble fiber benefits. that sounded like complete bullsh*t, but what do you think ?

    1. The fibers are destroyed in a sense that you are no longer satiated as much. for example, a whole apple can fill you up more then a blended apple. This can be an issue for people who are overweight and do not want to consume excess sugar calories. Other than that, the fiber content itself is not diminished and you still get the benefits.

      1. so you still get the fiber benefits in the intestinal track ?

        i’m not too worried about the satiety issue personnaly. but i do want the intestinal track benefits of fibers.

        thanks

          1. Do we know whether the dietary fiber value shown on nutritiondata for the kale smoothie is simply a sum of the ingredients?
            To be persuaded that the fiber content of the kale smoothie was still
            “intact,” I would like to know blood sugar levels after consuming
            the smoothie vs blood sugar levels after consuming the same ingredients
            as whole food.

            1. Fruits are easily digested whether they are blended or not, and berries can have sugar spike blunting effects, even when table sugar is added to them

              http://www.ncbi.nlm.nih.gov/pubmed/21929838.1

              In terms of whole grains, highly refined whole wheat flour, such as whole wheat pastry flour, will cause a much greater spike in blood sugar as opposed to unrefined wheat berries.

  5. I have a question regarding oxalate in green smoothies. I have read a few pros and cons regarding the oxalate in green smoothies and now I’m at a lost. Can you please let me know if green smoothies are a huge negative in a healthy lifestyle? I would greatly appreciate your response. Thank you!

    1. Unless you have a severe kidney issues, oxalates in greens are of no issue. Furthermore, not all greens have a high oxalate content. Kale, bok choy, arugala and collards are fairly low oxalate greens.

      1. I have the same question as alina – everywhere I look there is contradictory information out there on oxalic acid in food, not only for kidney stones but other issues as well. I have green smoothies every day including lots of these foods – parsley, cabbage, spinach, kale, chard, celery etc. This site brings up a solution – including adding calcium, magnesium and iodine to your smoothie and also cooking your kale (or spinach or whatever) before adding it to a smoothie (ick). http://www.bulletproofexec.com/the-kale-shake-is-awesome-so-upgrade-it/
        Would be interested in a critique of the discussion brought up here and a real investigation into this issue. Thank you!

  6. Are green smoothies good for you? Yes.
    But, is the lack of chewing bad for you?
    There are vegans that do only green smoothies for weeks, or only fruit smoothies for weeks(not saying thats healthy imo). So what about chewing? do we neet it?

    1. You can chew a smoothie and it is recommended to drink slowly and take care that every “bite” of smoothie is blended with saliva. ;)

  7. I’m still chewing on Brian Clement’s claim that blending is bad because it causes more oxidation than normal. Any thoughts on that? Would high speed blending be even worse than regular blending because of the higher temperatures generated?

  8. Nearly my total intake of fruits and vegetables for a year has been green smoothies of vegetables and weeds, mostly the leaves. For example I blend the leaves of broccoli, I seldom eat the flower. Apparently all I need is in the leaves. With the leaves I blend apple, pear, or other fruit for nutrition and taste. I am more healthy now than when I started this experiment.

    I bring kale, etc. into the house for the winter; and they feed me all winter. This year I will freeze some leaves and use them in the smoothies too in winter. Ground flax seeds and a Vit B12 supplement sometimes go into the smoothie too, because I am vegan.

  9. Acid-like burn from too many greens in my green smoothies??

    For over 10 days My tongue went from VERY deep center furrow and a burned feeling-highly sensitive to all foods as when I have overdosed on Pineapple. I had been drinking DAILY 20-25 ozs. of wonderful green smoothies with mostly collards, kale, and romaine lettuce and spinach with 1/2 banana, some chia seeds or ground flax, and blueberries and/or say, 1/2 cup mangoes on some days. So I cut out the mangoes, then the cruciferous ( the major part of my smoothies) and just used the spinach and banana, then just carrots and almond milk, some seeds and spinach.

    MIssing the greens a lot! Suspect that I over did the raw cruciferous veggies.(Yes, I saw your “overdosing on smoothies video”) My tongue is much better, but still slightly burned feeling. Has anyone experienced this reaction? I have thought of going on a water fast (ugh)to totally rest the poor thing since any food (esp. citric acid of course) irritates it a little.
    Any advice or antidote?
    Thank you for your fabulous site and sweet humanity and reasonable attitude (“Well, if you prefer treated chocolate, just add one more spoonful of the less potent one!”).
    Your non-religious, secular, non fanatic approach and humor are a delight!

    1. Thank you for posting your condition. Yes, I have been experiencing a burning tongue and lips for several months, and only recently did I finally pinpoint the source. Green smoothies. Ugh. I rarely eat meat, so I must substitute foods high in iron, which leafy greens do just that. My nutritionist suggested steaming the greens to neutralize the oxalate acid, which could be the cuplprit. Unfortunately, some nutrients will be destroyed, but others like iron are somewhat heat-resistant. In time I will have my blood tested again to be sure that I am getting enough iron from the steamed greens.

      1. Thank you Dannie. You are the first to mention this experience similar to mine. After 10 months, I still have a slight acid tongue, slight numbness on the surface. But I am no longer highly intolerant of citrus fruit. I never gave up green smoothies for longer than 3 days. Perhaps unwisely, I just kept drinking our very green smoothies and the condition is less bothersome. Am I damaging my tongue? Is it contributing to inflammation? I do not know, and am surprised that there is not more buzz about this online. I am not allergic to many things and do not want to give up smoothies. I do think it is the greens (kale, collards, spinach combo), but so far I have not been willing to take them out of my smoothies since nice things have happened to my body since drinking them (nearly complete disappearance of 30-year eczema on feet and sometimes hands).

        Dr. Greger’s answer above in this “Ask the Dr.” section:

        I’m currently compiling all the data in the scientific literature on the health effects of green smoothie consumption (for example there was a promising experimental trial recently performed in the UK). So stay tuned for a smoothie video in the 2013 batch I’m currently working on. Make sure you’re subscribed so you don’t miss it!

        I guess he did not come across this reaction in the published research.
        Let us know if steaming the greens helps and if you think your culprit really is oxalic acid!
        Thanks for your lead!
        Gayle

  10. Follow-up on “Acid-like burn from too many green smoothies?” post one month later.
    My tongue is somewhat better, but still feels like i have a too-hot coffee burn every day. I tried taking this or that out of my smoothies with no luck. Tried going off smoothies for 2 days, no difference. I am now hyper-sensitive to lemons and oranges and won’t get near pineapples. But the greens seem sufficient to irritate my tongue and if I get really tired of this I guess I shall have to try giving them up for a long while. Has no one else had this reaction?

    1. Gayle: Sorry to hear about all your green woes. I haven’t heard of this problem myself. Could it be a developing allergy???

      I just wanted to let you know that your posts were read. And I hope someone will be able to help or that you will find your solution.

  11. Did this 2013 smoothie video ever happen? I like to see it. I like smoothies and regardless of what some of the other Docs say, I think they are of value.

    1. I just registered and subscribed to this site. I’m also looking for the 2013 smoothie video Dr. Greger said he was going to post. I used the search bar above for “smoothie” and it doesn’t come up. Is there a way to search videos by year?

  12. Throwing a ton of vegetables, fruit, etc. into a Vitamix and pureeing it all is not nearly as good for you as eating the constituent parts as ‘real food’ (whether raw or steamed). As someone commented previously, and as you yourself demonstrated in the http://nutritionfacts.org/video/is-bacon-good-or-is-spinach-bad/ series, chewing (saliva) yields nitrates => nitrites => nitric oxide.

    Plus, as Dr. Caldwell Esselstyn, Jr. teaches here http://www.dresselstyn.com/site/faq/ (third from bottom), smoothies destroy the fiber of the component foods (despite what all the Vitamix and Blendtec salesmen say during their demonstrations). I can eat one apple, perhaps two if I try, but I can drink four or five smoothie apples easily, along with a whole bunch of spinach, carrots, berries, etc. Just as animals have bones to keep them up, plants have fiber. Destroy the fiber by pulverizing it and you no longer have fiber—you have liquid. No chewing, much less fiber, and quicker adsorption. Think of the reaction rate experiment you did in high school chemistry with zinc pellets and various molarities of HCl. Whatever the reaction rate is, if you add the same molarity HCl to zinc powder, the reaction goes “explosive” (very fast). This is why grain isn’t explosive but grain dust, if exposed to an ignition source, is explosive. (i.e. grain elevator explosions).

    The high fiber of eating foods with their fiber intact slows adsorption, which counteracts the effects of fructose in fruit, etc. If you blend your fruit, you’re getting hit with a load of fructose without the benefit of the fiber that accompanies it. See, e.g., http://well.blogs.nytimes.com/2013/07/31/making-the-case-for-eating-fruit/ (short), http://www.singjupost.com/bitter-truth-sugar-robert-lustig-full-transcript/ (long).

    Does an intact baked potato have more fiber than blending the potato in a Vitamix and having a potato smoothie? Absolutely! Does eating two whole carrots have more fiber than blending two carrots in a Blendtec and drinking it down? You bet! And in both cases, chewing a whole baked potato or two whole carrots does not increase the surface area of the food you swallow nearly as much as the Vitamix or Blendtec. Therefore, it takes longer to digest a baked potato or whole carrots than a potato or carrot smoothie. Why? Because you have larger bits with the fiber intact. It’s the difference between a bunch of grain (which won’t explode) and a bunch of grain dust (which will).

    Please correct this error.

  13. I was searching for some info about (green) smoothies and absorption, but I had no luck. I found this article (http://nutritionstudies.org/are-smoothies-good-or-bad/) by T.M.Campbell, talking mostly about high caloric intake (which I don’t find relevant, since I know a lot of people who have difficulties
    to eat enough calories on a plant-based diet). I also checked your site and found this one and another one (http://nutritionfacts.org/questions/are-the-nutrients-from-blended-vegetables-absorbed-better-than-raw-vegetables/), but not the answer to my question.

    So, my question is: do you know of any kind of studies that would show that eating smoothies leads to worse absorption than eating whole fruits and veggies? Is this just a(nother) myth? Or is it true?

    1. Thanks for reposting your question, Maya. I think the logic is when we chew our food well we release salivary amylase, the first step in the digestive process, releasing many chemicals to assure stomach acid and all other organs responsible for digestion and absorption are “ready-to-go”. Perhaps when we make smoothies this process is downgraded? I actually can’t seem to link to your sites. Do you mind double checking? What I see from one of Dr. Greger’s link is in regard to a study looking at fruit puree-based drinks and it’s effect on vasodilation and oxidative status (opening up blood vessels and boosting immunity). The smoothies seemed to make a noticeable difference.

      My personal thoughts are that smoothies are a great way to obtain nutrition for the day for many people. It really depends on what’s in it to make it healthful. You are still obtaining all the fiber versus juicing where all fiber is essentially lost. If a smoothie is going to help someone transition to a healthful diet I am all for it. If others enjoy eating whole foods and have the time to eat individual fruits, vegetables, nuts, and seeds, than also great! Smoothies can be an overload of fruit sugars and calories for severe diabetes or someone trying to lose weight, but again it is how you make the smoothie, right? I also agree with you when you say “a lot of people who have difficulties
      to eat enough calories on a plant-based diet” therefore smoothies are a solution for folks transitioning to a plant-based diet.

      I am sure others have more insight than me on this matter. I think Dr, Greger said he was updating something on this topic. I’ll double check. Stay tuned!

      Joseph

  14. Yes green smoothies are very healthy–but not every day for some people–they are high in oxalates. Oxalates are linked to kidney stones and hypothyroid disease as I understand it. Spinach has a lot of oxalates raw but they are reduced when heated to 135 degrees I believe. I’m no scientist–two associates degrees in criminal justice lol–but it is something to consider…just don’t be surprised if you have low energy and are peeing out calcium stones…hope not though!!!

    Correct me if I’m wrong–I know a ton of articles and web sites that tell me I’m right–in just too lazy to compile them all……….zzzzzzz. What? Lol

  15. I was advised that every time you sip a mouthful of smoothie just put a small chunk of raw carrot/celery etc in your mouth and chew it approx 30 times before swallowing the mouthful of smoothie – that way you sort of get the best of both worlds.

  16. Is there are scientific proof that blending different fruits or vegetables that have a unique water content means your body can’t effectively digest them? Someone is “claiming” that because High water content foods digest faster i.e. watermelon and low water content foods digest slower i.e. nuts, it means that a smoothie can spoil the process for your body and your body can miss out on the full nutritional benefits.

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