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Can Green Smoothies “DEVASTATE” Your Health?

Robyn Openshaw - Jun 01, 2012 - This Post May Contain Affiliate Links

Sarah the Healthy Home Economist online recently posted an article about how green smoothies can “DEVASTATE” your health.  The content was so unsubstantiated that at first I refused to respond to it. But Amanda said, “She has a big audience and people are freaking out about it.”

Sarah cites the oxalates phenomenon, wherein a natural compound (oxalates) occasionally bind to calcium to cause kidney stones. (She infers, without citing evidence, that other more serious health consequences could also be possible.) Greens have oxalic acid in them. Sarah makes several logic leaps and concludes that no one should be drinking green smoothies.

I’m not going to promote her blog article by pointing to it here. She rates her content for how controversial it is. Controversy generates more readers, I guess. It also has the potential to do harm, if what you’re saying is (a) undocumented, (b) contrary to hundreds of studies about the benefits of greens, and (c) featuring a bizarre and untenable conclusion.

Just because someone posts stuff on the internet does not automatically endow that person with credibility. Her argument locks in on a detail — that greens are high in oxalic acid — and misses the larger picture.

Only one source is listed at the end of her article and none are quoted or referenced. The source is a PhD’s book on oxalates and autism and “chronic disorders,” but she never quotes the author or anyone or anything else, so I’m not sure how many of her claims came from this one guy, or what.

I don’t bet the farm on one book or one source. There are quite a few other sources that show that some of the anti-nutrients in our most nutrition-dense foods, actually work together synergistically for our health, rather than against it. I’ve done quite a few blog series on anti-nutrients such as oxalates, goitrogens, purines, and phytates, concluding that none of the anti-nutrients should generally cause people to avoid foods containing them.

Note that at the end of the article, Sarah says to eat greens, if you like them, but not very much. Always cook them, she says, and eat them with butter.

Wow! Really?

Let me quote Dr. Norman Walker in his book Fresh Vegetable and Fruit Juices: What’s Missing in Your Body?

“Spinach should never be eaten when cooked unless we are particularly anxious to accumulate oxalic acid crystals in our kidneys with the consequent pain and kidney trouble. When spinach is cooked or canned, the oxalic acid atoms become inorganic as a result of excessive heat and may form oxalic acid crystals in the kidneys.

“When the food is raw, whether whole or in the form of juice, every atom in such food is vital ORGANIC and is replete with enzymes. Therefore, the oxalic acid in our raw vegetables and their juices is organic, and as such is not only beneficial but essential for the physiological functions of the body.

“The oxalic acid in cooked and processed foods, however, is definitely dead, or INORGANIC, and as such is both pernicious and destructive. Oxalic acid readily combines with calcium. If these are both organic, the result is a beneficial constructive combination, as the former helps the digestive assimilation of the latter, at the same time stimulating the peristaltic functions in the body.

“When the oxalic acid has become INORGANIC by cooking or processing the foods that contain it, then this acid forms an interlocking compound with the calcium, even combining with the calcium in other foods eaten during the same meal, destroying the nourishing value of both. This results in such a serious deficiency of calcium that it has been known to cause decomposition of the bones.”

So according to Dr. Walker, what Sarah is telling her readers to do is really terrible advice.

One of my favorite sources is George Mateljan, because his staff, and his book The World’s Healthiest Foods, review and quote a tremendous amount of empirical data before making claims. Each section contains an extensive bibliography, and the conclusions are scientific and objective.

He says that a review of the peer-reviewed research reveals that the ability of oxalates to lower calcium absorption is small and does not outweigh the ability of those foods to contribute significant calcium to the diet, since spinach is rich in calcium.

So, one of the primary recommendations of most the sources I’ve read, to avoid stones forming in the body, is to get plenty of calcium from plant sources.

So, the high calcium content in spinach may actually inhibit the formation of stones, even though spinach is also high in oxalates. This is at least some logic or evidence, then, underpinning my theory that there are far more synergies than we currently know about in whole, raw plant foods leading to their clear, incontrovertible place (based on volumes of published research) as the necessary mainstay in our diet. We know that people the world over who eat mostly whole, raw foods simply don’t get sick. We don’t always know WHY.

So screaming that the sky is falling about one compound—in an entire class of our most nutritious foods—seems not only unwise, but even irresponsible, if you have an audience and give nutrition advice.

The jury is still out on so many of the issues Sarah the Healthy Home Economist takes strong, unilateral stands on. For instance, what really causes oxalic acid buildup. (She quotes ZERO evidence that greens do.) Whether greens are high in oxalates are only ONE issue related to whether they cause kidney stones. What if they also have dozens of other nutrient compounds, and fiber, that PREVENT stones from forming? A relevant example would be Mateljan’s review of the published, peer-reviewed literature on spinach, oxalates, and calcium as mentioned earlier.

After I investigated this issue, I wrote this in Chapter 1 of 12 Steps to Whole Foods:

“The research is not clear that restricting foods such as spinach helps prevent stones in those who have previously had them. Many researchers believe that dietary restriction cannot reduce risk of stone formation. In fact, some foods that were assumed to increase stone formation because of oxalate content (like black tea) have appeared in more recent research to have a preventative effect.

“Further, cooking has a small impact (about 10%) on the oxalate content of foods, with no statistically significant lowering of oxalates following blanching or boiling of greens. It appears that the nutritional advantages of eating raw greens continue to far outweigh any benefit of cooking them.”

And yet, with slim evidence, if any, Sarah says green smoothies can “devastate” your health and advises at the end of the article, “Skip the Green Smoothies!”

She undertakes no discussion of the true baddies that cause kidney stones:

Soft drinks


Animal proteins

Salty foods (or any refined salt)

Oxalates in spinach (also strawberries, soy, and many other foods) can be difficult to digest for a tiny percentage of the population who are suffering from a few very rare disorders (absorptive hypercalciuria type II, enteric hyperoxaluria, primary hyperoxaluria). But let’s not throw the baby out with the bath water here. If you don’t have these disorders, and 99+% of those reading this don’t, greens are not just good food—they are powerful good medicine!

Leafy greens are the most nutrient dense foods on the planet, and cooking them as Sarah instructs kills 100% of their enzymes, and most of their vitamins and minerals, too.

Sarah the Healthy Home Economist uses hyperbolic words to terrify people that eating nutrient dense foods could kill them, but she cites no research whatsoever. She implies that cases of painful sex are on the rise (where does that data come from? Is there any data?) and that oxalates are a “possible culprit.”

There are no references to check, and the bigger issue to me is, if people develop kidney stones, or crystalline deposits in other parts of the body, are greens the real culprit? How would you isolate that factor? Show me the study that did.

It’s terribly unlikely that greens are why we have lots of kidney stones, since almost nobody in America eats very much green food.

And in addition to thousands of testimonials we’ve received, my own research (175 subjects) shows massive health benefits to the green smoothie habit, as published in my bestselling book, The Green Smoothies Diet. In that research, not one person reported kidney stones as a side effect of starting the daily green-drink habit. And yes, we asked.

Nutritionally, crystalline deposits are likely caused by highly acidic foods, especially salt, and not drinking lots of water.

So let’s minimize or eliminate the baddies, listed above. Let’s eat more of the foods that have been linked by hundreds of studies world-wide, to ideal weight and minimized disease risk.

(Dr. Joel Fuhrman does this best, in Eat to Live, quoting literally hundreds of published studies showing the benefits of eating plant foods. This is highly recommended reading.)

Let’s don’t kill greens with cooking, and slather butter on them.

If you’re worried about oxalates, let’s not “throw the baby out with the bathwater,” because people who don’t metabolize that anti-nutrient well need the nutrition in the leafy greens as much as anyone, if not more. Instead:

Let’s rotate greens, use a wide variety in our green drinks—not just spinach. Amanda says a friend of hers had oxalate issues and one took a calcium-magnesium supplement and the pain went away. Several experts I have read suggest getting more calcium from plant sources.

And, eat some good fats with your green smoothie, like avocado or coconut oil or flax oil, to increase calcium absorption. One of my favorite lunches is a quart of green smoothie, with some homemade guacamole and “corn chips” (organic corn tortillas, quartered with a pizza cutter and broiled on both sides, no oil or salt needed).

Posted in: 12 Steps To Whole Food, Green Smoothies, Whole Food

79 thoughts on “Can Green Smoothies “DEVASTATE” Your Health?”

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  1. Anonymous says:

    Perfectly put. Go team Robyn! 🙂 I’ve had so many friends and family ask me about Sarahs article I’m getting ready to forward this to all of them.

  2. Anonymous says:

    I have been a follower of GSG for a long time and would drink GS daily, but I have to say that I do think there is a thing with these oxalates or possibly just with cold smoothies. It wasn’t until after a year of doing GS and eating healthy that my body went into an anxiety mode and was very cold (low body temp). Also, I have a friend whose boy does react with anxiety when he has green smoothies, or other things on the high oxalate food lists (so not just greens). I just want to put a counterpoint because I have seen and experienced not the best results with green smoothies and it wasn’t because I was eating junk on the side hoping for a miracle. I also don’t believe it was because I was “detoxing”. Anyways I guess my main point is not every food or “diet” works for everyone and each persons body can react in different ways. I think it is good to acknowledge this, and it is helpful if people do try to listen to their bodies cues on whether something is working or not.

  3. Anonymous says:

    Bravo for the very nice answer.

    As far as I have read, there is also a big difference between organic and non-organic spinach. The latter is richer with oxalates, as far as I have read.

    Furthermore, baby spinach has the least amount of oxalates. ( that is according to the same source – I can’t remember where I read it, sorry-) The last, but not least, oxalates are usually in the steam, so if you cut a steam of the bigger leaves of spinach, that should be useful.

    Now, I being a pregnant woman can’t recall the source of this information, but I remember it made a lot of sense to me when I read it.

    I hope it helps


    Keep the great work going… 🙂 (Sarah text does not make a lot of sense anyway, if you have ever read anything about raw food and health in that matter. Personally to me it sounds like a blog of some huge pharmaceutical company:D The more people take care of their nutrition and health, the less money big companies earn)

  4. Robyn,

    I’ve been drinking green smoothies for over a year now and had my first kidney stones a few weeks ago–never, ever had a kidney stone before. My urologist said my stones were due to the oxalates in the spinach in my green smoothies. He told me to either cut back on the spinach or increase my fluid levels. I’m still drinking my smoothies, but not every day.

    Carl Johnson

    1. Robyn Openshaw says:

      Carl, I wonder if that’s true. It’s hard to isolate a factor, with human beings. I agree with the “increase the fluid levels” part, and please make sure you’re getting enough good fats, with your greens, too.

  5. Anonymous says:

    What. An. Idiot. I’m sorry, did I say ‘idiot’? I meant “IDIOT!!!!” There – that’s better. This article made me really hungry, and I just polished off a giant green smoothie full of spinach and romaine and parsley. Can’t wait to have another at lunch. What irresponsible and self-seeking rubbish. She will be less than a flash in the pan with this article, and GSG will continue to be a strong, steady healthful influence on thinking minds for years to come. How utterly ridiculous to think that God is so inept as to create a whole planet full of natural foods for us to eat that are actually not what we need AT ALL to live the life He gave us. How wonderful it must be for this woman to be smarter than God Almighty. I wouldn’t stand to close to her, folks – you don’t want to be there when the lightning strike hits. I hear lightning is ALMOST as bad for you as spinach…

    1. tendr says:

      I wouldn’t be so mean. I have interstitial = hell on earth. And the high oxalate foods send me into so much pain i’d rather be in a coma.

  6. Anonymous says:

    Just wanted to say thanks for your article on greens and oxalates. I know by how feel that smoothies filled with greens are totally healthy. I started drinking 2 a day almost two years ago. I also donated a kidney to a friend 10 months ago. I know within my heart it wouldn’t been possible without adding green smoothies to my diet. I’m 53 and my kidney function is excellent . I passed numerous tests with flying colors. Green smoothies are mine for life 🙂

    1. Esther says:

      I am new to making smoothies and looking to get at least 1000 mg of calcium out of my smoothie. Do you have any suggestions on what i should put in it? I’ve never made one before.
      thanks for any ideas.

  7. Anonymous says:

    I am now apparently prone to rather sizable kidney stones. However, I notice that the MORE green smoothies I consume, the LESS problems I have with the stones. I *have* heard from some doctors, however, that greens should be cooked (when not consuming them in a well-blended up smoothie), so I am going to look more into this issue. My kidney stones don’t need any help. 😉

    1. Robyn Openshaw says:

      Shannon, I believe that somebody said that—about cooking greens neutralizing oxalates—and many doctors just repeat it, and it gets passed all over the internet. All the evidence I have found points to that being basically an old wives’ tale!

  8. Anonymous says:

    Well put!!!

  9. Anonymous says:

    I came across that blog post from a friend’s FB post. I followed the one source link she gave and was dismayed to find the source from somewhere I trust. Dismayed because I was disappointed they would publish such a thing, it is not what I expect from them. And this was several years old already. In the comments section one woman refuted it saying that in those rare conditions they have found a lack of a particular probiotic that helps us break down and assimilate oxalic acid. So – one more culprit to look at – antibiotics. And a new remedy – get your probiotics and drink your green smoothie! 🙂

    This is just one article I found in a quick search on Oxalobacter Formigenes. This was a treatment that didn’t even include that particular strain.

  10. Thanks you for this article, Robyn. A lot of great info to consider.

  11. Anonymous says:

    Robyn, The proof of the pudding is in the eating. The fact that your previously asthmatic children are now competitive athletes speaks volumes. I know of many many people who have regained their health after adopting a plant based, healthful diet. There is a technical term we use at the Smith home to describe people who spout off unsubstantiated information and expect people to believe their unlikely theories…”FOS”. The condition they suffer from is scientifically described as “Opti-rectal disease” or “Cranio-rectal inversion”. You get the drift. Some simply call it stupidity. In any case, I don’t think you suffer from any of the above. Thanks for what you do.

    I am excited that you are looking into natural treatments of cancer. Please take a minute to look at . I personally know of several people who have reversed cancer that they were told was terminal, and they did it with diet. There is a doctor whose clinic has done this for many years, and there is a movie about it on Netflix called “The Beautiful Truth”.

    1. Robyn Openshaw says:

      Maytha, thank you. I know Hallelujah Acres pretty well and have talked with them before and I have seen and own The Beautiful Truth.

  12. Anonymous says:

    People who believe everything Sarah the Healthy Home Economist says need to start thinking for themselves. While I read her blog, I am off put by her militant stance and her arrogance in her belief that she knows everything. She does have some valid point in her blog- sometimes. She tends to bash any food lifestyle that isn’t in line with hers, which is just not necessary. I know people who have developed kidneys stones from eating lots of cooked greens, but never raw greens. We need to stop believing everything we read from so called authorities and decide for ourselves after careful research and meditation. And sometimes what works for one doesn’t work for another- so there is a bit of knowing your own body and listening to it involved in our health as well.

  13. Anonymous says:

    Robyn, thanks for writing this – and so politely, too.

  14. Thanks for adding your voice to the debate! I’ve been annoyed by Sarah’s arrogant stance on this and her refusal to acknowledge a differing point of view.
    By the way, I’ve been enjoying green smoothies for a few months now, partly due to stumbling on your site so THANKS!

  15. http://N/A says:

    Since stating green smoothies in Aug of 2011, within 2 weeks I noticed I haven’t needed my 2 asthma sprays (1 type for maintenance the other fast acting for attacs). I haven’t filled my persription in 10 months! Now heres the kicker… 2 months ago I went to my eye Dr. She was scratching her head saying I don’t understand. I asked what? she replied, You’re seeing better with less power in your prescription and reading 2 lines better on the eye chart than last year!!! WoooHooo! go green smoothies!

  16. Robyn,
    I normally love what you post. I get your posts through my email and have for years but please be open minded on this topic. It’s not as cut and dried as both of you and Sarah may want to think. I don’t have kidney stones but I cannot tolerate oxalates. I found that out after damaging my body with them through green smoothies and juicing. I don’t think I’m as rare of case as you may think. I cannot eat ANY oxalates now without a reaction which was not the case prior to switching to a healthier whole food diet. The answer is to heal the gut *first* then add the greens and it’s a lot more detailed of a task than just drinking smoothies. I desire to eat more greens again someday and don’t think they will hurt me when I have proper digestion. I do think it’s important to not cling to any diet paradigm and make sure to adjust to each persons situation. Also, I think it’s important to remember that a big percent of the population suffers from poor digestion after coming off of processed foods so this problem may be more common than you want to think. I’ve had so many people come to me amazed that they didn’t know this could happen and asking for advice. I also think many more people are suffering from candida than realize it which also causes problems when eating oxalates. I think the candida is probably the main problem for most. I can eat meat but still cannot eat spinach without a reaction. I think you are probably helping a lot of people achieve great health and if you look at this open mindedly you will be even more valuable to them when you are able to identify this issue in the ones who have a problem early on. It showed up for me in small itchy rashes on my fingers in the beginning and over the course of two years spread as rashes up both hands and arms. I stopped eating all of the greens and the rashes went away! I can eat low oxalate greens now with no problem.

  17. Anonymous says:

    Robyn: I started with Eat to Live and bought your wonderful books also etc in Jan. 2011. I put raw spinach in nearly every Smoothie. I had lost 51 pounds. First let me say I am a believer in green smoothies…

    I am quite saddened to say that last month I was on the floor in 20 minutes writhing in pain from 2 kidney stones and had to have them blasted the next day. Now they found another. I have never had a problem before. Now some $15,000 later I am scared to resume it! I know the benefits but I now know the pain also. Coincidence? I don’t know.

  18. Anonymous says:

    PS–my ingredients were organic!

  19. Anonymous says:

    I love your green smoothies but I have hypothyroid and it is said that one should avoid spinach and kale and broccoli and cabbage.

  20. Anonymous says:

    Wow, that blog by S the HHE was one of the most ridiculous things I have ever read. Her conclusions were completely off the mark. There are so many factors in people’s lives besides diet, that even a controlled study would be meaningless. First off, I have yet to meet a person who has suffered kidney stones that wasn’t on prescription meds. Stress and I think especially a stressful relationship can have a huge impact on health and organ function. I have a green smoothie made with a ton of spinach almost every day, and have been doing it for a couple years. When I skip a day, I can feel it, I bloat, my energy decreases, etc.. Carl, maybe there are other factors that should be looked upon. It really sucks when people who are in a position to influence others, make such uneducated and sweeping generalizations without credibility

  21. Dear Robyn,

    I am a huge fan of yours. I discovered Green Smoothie Girl almost two years ago and fell in love with your message. I have been drinking green smoothies ever since and feel great. Plus, I have a nine-year-old daughter who also loves green smoothies and I feel good about her drinking them! I love spinach and I eat it (mainly) raw, but I also saute it slightly when I add it to veggie pizza, lasagna, etc. My family and I have a huge garden and grow a lot of our own veggies. I’m 46-years-old and in better health than ever before! No one is going to tell me not to eat my spinach raw—especially when they don’t have any solid evidence to back it up. And I would never saute it in butter—yuck!

    I was really upset yesterday when I read this post and checked out Sarah’s blog (for the first time). After reading her (arrogant) bio and a few of her articles, I am convinced that she is not a person to take any nutritional advice from and I do not plan on visiting her site again.

    Here is a great online source of info talking about Oxalates. I think it will be helpful for a lot of your readers. I’m a huge advocate of moderation and balance in everything you eat and do.

    Thanks for all of the amazing work you do! I’m grateful for your insight on nutrition! I think I’m going to make a green smoothie right now with a handful of spinach!!! YUM!

    Take care, Jean

  22. Anonymous says:

    Excellent response, Robyn….. I am a nurse and it makes me nuts when I read sensationalistic articles with no evidenced based-research to back it up….. I was a lactation consultant for 25 years, and you can just imagine the deeply ingrained myths and old wives tales that still persist today in our Western culture concerning breastfeeding. Unfortunately many health professionals are not up to date in many areas – nutrition, especially – and much of their advice is incorrect, outdated, or simply what they’ve “heard”…..but being health professionals, their word is taken as gospel truth.
    It was you and your great information that inspired my journey into the world of green smoothies last summer , and now I am working towards a primarily plant-based, living and raw foods diet. Thank you for you commitment to the health and wellness of so many people.
    Keep on keeping on!
    Sandey in Panama

  23. Anonymous says:

    Hmmm. It’s an interesting argument. I’ve never had a kidney stone, but my brother-in-law and his wife have had quite a few. They both eat a lot of fast food, restaurant food, Monster energy drinks, and coffee. I’ve never seen them eat raw greens, ever. I’ll take my chances with green smoothies.

  24. Excellent response, Robyn. Thanks for following Amanda’s advice and addressing THHE’s blog. Sara is a bit arrogant/militant and your rebuttal was well documented and stated.

  25. Anonymous says:

    There is a lot of controversy on this topic, so I for one, was happy to have another opinion on the matter. I drank green smoothies for quite some time, but before her article even came out, I questioned the practice. It didn’t feel right for me at the time. I think that green smoothies work for many and are far better food than the junk food many eat these days, even with some anti-nutrients in them, but I think it is very beneficial to question ideas as we each strive to be healthy. All bodies are different and there is not a one size fits all diet. They many not be for everyone even though green smoothies have done good for so many people.

  26. Anonymous says:

    I actually really appreciated that article. I drank green smoothies for a long time and I felt good in the beginning, but started feeling bad and so I stopped drinking them, even after I convinced several others to drink green smoothies as well. My goal is to eat food that makes my body feel good. Sarah’s article was great to help me have greater understanding. I know you have sincere desires to help people be healthy, but I think I am thankful that there are other opinions. When I learned about oxalates, it made so much sense to me and I was so happy that I finally learned that eating certain foods raw was actually detrimental. I despised raw greens and drank it because they were good for me but I no longer feel guilty that I cook my greens! Yum. Thanks for doing your best to help others be healthy. I wish green smoothies made me feel good, but they just don’t.
    Sincerely, Julie

  27. Anonymous says:

    I am trying to figure out if my comments post.

  28. Truth is its’ own authority and needs no reference because of the author of truth whose Spirit dwells within us. Untrue extrapolations from truth certainly do not help the discussion. Thank you for your efforts here. I would like to add my belief that there are conditions wherein “green smoothies” lead directly to diminished health. Dr. Fuhrman, McDougall, and others qualify the benefits of drinking “green smoothies” with resounding caution to all who suffer from diabetes, insulin resistance, or any other blood glucose-related disorder, citing fully their reasons for giving these cautions and specific directive to all such persons. Given that most of today’s population is insulin resistant and a third or more are diabetic, it would be awesome if you would address issues such as the following:

    1. When do “green smoothies” lead to diminished eyesight, nerve, and organ damage?
    2. Under what conditions do “green smoothies” cause us to store body fat?”
    3. When do “green smoothies” lead to the loss of excess water weight?
    4. When do they lead to significant increases in water retention?
    5. When should we pay attention to feelings of nausea toward greens and why?

    I would love to see your talent grace the subject of why, when, and how “green smoothies” diminish health versus improve it. You are a powerful advocate for truth Robyn, and I know that doing so will serve to increase your readership and good influence. Thanks for all you do! Best! Jim

    1. Robyn Openshaw says:

      Hey Jim, when we write questions, they come with implied answers…..and I don’t think the answers here are clear or point in the direction of avoiding blended green drinks or all greens as was implied by the author of this article (blog post, really). Do YOU want to say something about this? Diabetics and any other insulin-resistant folks need to count their carbs and minimize the fruit in their smoothies, surely. I like to have them use fresh lemon juice and stevia to sweeten the smoothies, maybe a small amount of frozen berries or part of a tart apple.

  29. Anonymous says:

    I too like Brandie heard of a guy with kidney stones BUT he rarely ever ate anything healthy at all. Fast food was his primary diet, heavy on the processed/packaged foods, animal, loads of dairy and soda was his best friend! I have gone through so many bags of Costco spinach and have just kept in mind Robyn’s advice of Rotate your greens and change it up. Also, for people concerned about hypo-thyroid issues …maybe iodine, sea vegetables and among all the MANY benefits of the Chia seed I think I also read they too help the thyroid. I can’t imagine giving up my green smoothies, this has definitely put me on a better path. 12 Steps is amazing Robyn and I feel so grateful to everything I learn from you.

  30. Anonymous says:

    for everything! Typed too fast 🙂

  31. Anonymous says:

    Blenders are destructive by nature, they cause oxidation, and recent popular ones I’ve read can heat up soup, due to their high motor speed and pulverizing ability. So if greens are getting cooked up in a blender, which according to your sources cooking them makes them unhealthy…compared to greens in their raw natural form, why should anyone be drinking green smoothies? Chewing on greens naturally with our teeth like cows and other herbivores do seems better, even if it takes too much time to do. I’m glad I never got rid of my molars.

  32. Hi, Robyn.
    Although I agree with your stance that eating raw greens is healthy for many people and I truly appreciate that you are encouraging people to eat more healthy vegetables and fruits, I want to point out that many of the “facts” in your above article about oxalate are not correct. In fact, I was dismayed that your source Dr. Norman Walker was so wrong about oxalate and is spreading such horrible advice and information. Quickly, I’ll point out that oxalic acid is a naturally occurring acid in plants and animals that has a highly toxic affect when it builds up in your system. It cannot be neutralized or made “inactive.” In fact, boiling medium or low oxalate greens can substantially lower the soluble oxalate content of these greens if you throw away the cooking water because some of the oxalate leaches out. No amount of cooking will make spinach safe for people with oxalate issues, but it does make a huge difference for other medium/low oxalate greens like turnip greens and kale.

    The bottom line is that some people need to worry about oxalate and some don’t. The real problem is that it’s almost impossible to tell if you need to worry about oxalate until it’s too late. This is because most people do not exhibit oxalate-related symptoms until they reach a toxic threshold of oxalate in their systems and then they can begin to have very uncomfortable and sometimes serious health issues. The most common cause of a toxic build-up of oxalate in the system is poor intestinal health or function. This includes an unhealthy of unbalanced intestinal flora (often from overuse of antibiotics), irritable bowel syndrome, leaky gut, celiac disease, fat malabsorption, chronic constipation, scarring or a shortened intestinal length due to surgery. If you or your readers have poor gut function (and unfortunately many American do), then I urge them to pay attention to oxalate in their greens and to pursue ways of improving gut health. If you have rock solid healthy digestion, then most likely you don’t need to worry about oxalate (unless you are eating a Very High Oxalate Diet (which has been connected to osteoporosis).

    About 30 oxalate-related symptoms have been identified with more being discovered each year. Most of the medical community has not caught up with these new developments, but a few scientists and doctors are actively researching the role oxalate plays in autism, genital pain (especially vulvar vestibulitis), joint pain, bladder pain (including interstitial cystitis), rectal pain, burning pains in any part of the body, burning mouth syndrome, fibromyalgia, thyroid disease, chronic fatigue, “brain fog”, osteoporosis, lichen schlerosis, certain other skin rashes/conditions, COPD, irritable bowel syndrome, leaky gut syndrome, kidney stones, burning or stabbing pains in the eye, muscle pain and certain behavioral disorders (to name a few!). Not every one who has these symptoms or disorders has an oxalate problem, but many of these health issues can become a lot worse in people who eat high oxalate diets (and for some can become much better on a low oxalate diet). I personally had 15 oxalate-related symptoms and conditions that have completely healed or become substantially better on a low oxalate diet (which I have been following for 20 years).

    One thing people can do if they are concerned about oxalate is to switch to using mostly low or medium oxalate greens in their smoothies and salads such as turnip greens, mustard greens, dino kale (low), curly kale (medium), romaine lettuce, cabbage, and collard greens. They may also want to reduce their intake of the two very high oxalate greens, spinach and Swiss Chard. I would also invite any of your readers who are concerned about oxalate to become more educated about oxalate from reputable sources:

    My blog has a lot of information and support for people who are on a low oxalate diet or are considering starting a low oxalate diet:

    Susan Owens, one of the leading oxalate scientists in the world, hosts a website “Low Oxalate Diet” as part of the Autism Research Institute:

    And Michelle at OxVox has backed up some of Sarah’s original source with references to the primary research articles:

    I appreciate that you are encouraging your readers to become more healthy by ditching the junk food and eating more raw fruits and vegetables. Our society needs this! But I do think keeping an open mind about oxalate and the serious health issues it can cause is important also.

    Thank you,

    1. Robyn Openshaw says:

      Heidi, thank you for that, especially for the list of lower-oxalate greens.

      However, as counterpoint, author Victoria Boutenko, my friend and companion in green-smoothie crime, has written this extremely detailed, source-rich article on all the research that oxalates are FRIEND RATHER THAN FOE. Before you change your diet to eliminate or massively reduce the highest micronutrient foods on the planet from your diet, the foods that are the crux of the primate diet worldwide (we share more than 98% of their DNA), you ought to read this documentation suggesting that greens may actually prevent kidney stones. We already know they prevent many, many other modern health risks. Read Victoria’s report HERE.

  33. That is somewhat distressing to hear, no matter how thin you slice it their must be some merit to both sides in regards to the oxalate debate. There seems to be however a great number of people enjoying daily green smoothies without the negative side effects. I imagine a large swath of these individuals also do not switch their greens up and allow a build up. My friend made a youtube video today for a kale and pear green smoothie, guy is is great shape and been making them for years without issue.

  34. Hmmm. Interesting reading everyone’s comments. As a Nutritional Microscopist I know that we ALL need to eat more Alkaline in general. When we go from a Standard American Diet (SAD) and hop onto the Green Smoothie road, there WILL be some detoxing affects. For the gal April who said she can’t tolerate oxalates at all, I say; be patient! Start with lightly steamed veggies. Clean out the gut! Check out Colonics! Do Parasite Cleanses….Wow, that can be IN-lightening!

    When some people say they “have a negative reaction” when they eat more greens, they are most likely, but not always, entering a cleansing. Be nice to yourself! Transition patiently onto more organic/fresh/living/live/raw foods. The gut is full of crap. (sorry, but true). Your reactions to healthy food is not going to go away over night. But it WILL be worth it!

    You’ll feel like a kid again (well, a healthy kid) Our digestive system isn’t a smooth hose, but full of kinks and bumps and pockets to hide all kinds of goodies (and not so). When I went onto the “raw food” diet years ago, it was a long process. I went from extremely tired in my 20’s to completely invigorated up to my 50’s now. It took 10 years, but was so interesting and amazing! I met wonderful people along the way, including my real self. BE PATIENT!

    Look at Genesis 1:29 and what GOD said for our first parents to Eat (remember Adam and Eve?) “And God said, Behold, I have given you every herb (includes greens) bearing seed which is upon the face of all the earth, and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat.” (pretty much rules out our SAD diet!)

    Also, remember that some of those negative reactions can be from the Chem Trails (Barium, etc.) that fall onto our crops. Grow your own food! Better yet, get a green house. Grow sprouts INSIDE. The body is a masterful, miracle “temple”. Trust good common sense. Trust God and trust the process of healing and good health. It works. And stop trying to make sense of the senseless. Now I think I will go finish my green smoothie….

  35. Anonymous says:

    I was devastated to read that green smoothies are bad for you!! I love them!! Need them!! Crave them!! I could never give them up. Sure I could leave the spinach out but give them up completely?? NEVER!

    I’ve only be drinking them for about a month now and I feel amazing. I can’t say I’ve lost any weight but then I haven’t been fanatical figuring if I got my body healthy then thin would follow!!

    Surely if you drink at least two liters of water each day, your body should be able to support a quart of spinach- and red chard-free smoothie??

  36. Anonymous says:

    Just want to pipe in to say that a family member has a history of oxalate crystal kidney stones – he had two episodes about a year apart. At the time he had been drinking about 5 cans of diet soft drinks per day, eating a diet of fried chicken, Chinese take-out, and luncheon meat sandwiches. He was following one of the hyped low-carb, high-protein diets. He never drank green smoothies, much less a spinach salad, or white bean-kale soup! He was told to avoid a list of about 50 foods but only two of them were a major part of his diet (soft drinks and processed foods).

    I think it’s terribly irresponsible to state that organic raw produce could “devastate” one’s health. It makes me sad to think that there are families taking this kind of rhetoric to heart and removing an incredibly nutritious, relatively inexpensive, tasty food from their diet.

  37. Perfect rebuttal! Thanks so much for standing up for health with a well researched and documented response! Green is the way to live!!! 🙂

  38. Anonymous says:

    @ Sheila

    Sheila stated, “I put raw spinach in nearly every Smoothie”. She later when on to say she suffered in agony from kidney stones.
    I am sorry that she had to go through that pain. What stood out for me was her comment that she put spinach in nearly EVERY smoothie. If you eat anything on a daily basis it has health consequences. The body needs variety. Smoothies should be mixed with a variety of greens. I mean I wouldn’t sit down to dinner and eat a plate of spinach almost EVERY night. So why do it with a smoothie? Let’s be honest, drinking a smoothie is a quick (lazy) way to sneak in some greens. Just be creative with it , there are other greens available besides spinach and Kale. I’m still doing research on this topic and have concluded that variety is key. Now to see what other kinds of greens to mix it up with.

  39. Anonymous says:

    Just a thought about those folks who feel they’ve had negative reactions to oxalates: There have been reported cases of negative reactions to just about EVERYTHING by someone, at sometime, somewhere! After first reading Sarah’s article, then Robyn’s rebuttal, it’s clear who makes more cogent logical argument. I’ve been using a Nutribullet for the past 30 days, generally doing at least two “Nutriblasts” per day, with leafy greens (usually organic baby spinach, sometimes mixing some organic kale in), and plan to continue doing so. I feel great, the science of eating nutrient dense food supports it, it makes good common sense, and with all due respect to Sarah, her article warning about green smoothies was very poorly supported by those pesky little things called -facts-. Thanks for the thoughtful response, Robyn! Obviously eating too much of anything isn’t a great idea, but a sensible, nutrient dense diet balanced with a variety of foods, including green smoothies, should be a huge dietary boon for anyone, especially those coming off the Standard American Diet (S.A.D.)

  40. Hi Robyn, I too came across this article on Green smoothies and the possible devastation. I don’t agree with it at all! You did a great job breaking down each point and with some good supporting facts that truly cause questionable thoughts on Sarah’s full understanding of the information. I recently launched a site called and would be honored if you would like to submit articles from time to time on site. The site just speaks to moms to helping to spread the knowledge of nutrition and ideas that they can implement in their lives and families lives! I will be adding recipes, and I do speak about some products that have been very successful in my life and my families. I am such a health advocate it’s a great way for me to get my voice out there. Please feel free to check it out at Thanks! 🙂

  41. Anonymous says:

    @ Cha

    I think your response was the first one to bring up a very important point that many are missing: variety! Don’t we all remember the rule of moderation? Anything and EVERYTHING in excess can be detrimental to our health. Variety and moderation are key. With that said, what is considered ‘moderation’ with green smoothies? 1x/day, 3x/week? multiple per day?

  42. Anonymous says:

    My biggest complaint with the original article is that it takes an all or nothing approach. Because 20% of the population suffers with this, all 100% should take precautions and grossly limit their intake. I believe there may be some truth in the matter. Different bodies and states of health react in various ways. Some people cannot tolerate gluten. Some people find grains or beans as a whole difficult to digest. It is reasonable that for a small portion of the population, oxalic acid provokes an unpleasant (to say the least) response.

    If a person is suffering from digestive issues that are not corrected from a primarily whole foods diet, i.e. – cutting out the biggest culprits such as sugar, caffeine and other processed foods, then absolutely take the necessary steps to get to your best place of nutrition.

    Pay attention to your body. Rotate your greens. Eat whole foods and a wide variety. However, in terms of the *class* of foods, just as I would not decide to only fruit a few times a week because diabetes is common, I would not stop eating foods with oxalic acid unless I had a medical diagnosis, symptoms, or a family history that led me down that road.

    There is a bigger question worth asking: if there is something broken in your body leading to a buildup of this oxalic acid — can it be fixed? Many food allergies last a lifetime, but I’m also constantly hearing miracles. Perhaps the focus should be on healing the gut & digestion, thyroid, etc, so that your body has the capability to draw nutrients from as many sources as possible.

  43. Karl says:

    I agree with most of your points, and agree that Oxalic Acid is not something to avoid at all costs. I’d like to point out two things, however: first, I would feel nervous eating tons of greens without thinking about the Oxalic Acid content, as there have been apparent cases of acute overdose of Oxalic Acid leading to death (see, e.g., Granted, we’re talking about 2-5 mg here, but I eat pounds of veggies at a time pretty regularly and a pound of spinach would contain something around 4mg of Oxalic Acid, so I would consider that a legitimate concern.

    Also, with regards to the discussion of the work of Dr. Norman Walker…while I agree that denaturing the molecules in our food probably have significant effects on the nutritional value thereof, the idea that calcium or oxalic acid cycle between “organic” and “inorganic” is, well, silly. Chemically speaking, an organic molecule is simply a molecule with a carbon (with some minor exceptions). As such, Oxalic Acid is always organic and calcium never is. I won’t get into the rest of the quote, but just that clear misstatement is enough to give me pause in considering the rest of what he has to say.

    Again, though, generally good job of pointing out some of the hidden assumptions in the work in question.

  44. Joi says:

    I’ve been a fan of Green Smoothie Girl for quite a while now and well-written, well-researched articles like this one is just one of the reasons.

    I’m having an issue with green smoothies and was wondering if anyone else had ever experienced anythings similar. I’d also love to hear any advice you may have!

    Since I began drinking green smoothies, regularly, I’ve experienced frequent (and painful) mouth ulcers and tongue pain. Half the time if feels like I’ve burned my tongue, when I haven’t. After a little research, I suspected that bananas were the culprit and stopped using them in my smoothies. However, it didn’t do the trick. I SO hoped it’d be that simple.

    I’m not saying this to try to turn anyone away from green smoothies. NO ONE else I know who drinks them regularly has this problem. Just me. Sigh.

    Is there anything I can do to salvage my relationship with green smoothies? I’ve examined every other food/drink in my diet and, sadly, green smoothies are the only thing that could be causing my strange problem.


    1. I have the exact same symptoms as you. I wonder if its pesticides. My greens were not organic. Were yours?

  45. Jennifer says:

    She also claims greens are the cause of vaginal yeast infections…? As you said, where is the study that shows this? Wow. I mean, when did oxalate crystals and fungus become the same thing?

  46. Sam says:

    I have had a similar reaction when eating raw celery and carrots (when they aren’t organic or from my backyard) I blame the pesticides. Burning and itchy throat, fat lip…stuff like that. Washing them better has sometimes decreased the reaction, cooking them always. Organic fixes it. Strawberries and green apples have done similar to my gums – hurting effect, discomfort. Consider that pesticide ladden things might be at fault.

    Just a possibility to consider.

    — Sam

  47. Dee says:

    thought I didn’t read through all the comments, this is responding to Sam responding to Joi:
    My son has a sensitivity to raw apples, cherries, peaches, etc. (swollen/itchy mouth, throat). Also, different members of the extended family have others (apples, carrots, etc.), along with his ortho. Online I’ve read of correlations between certain trees/grassses and foods such as this article:
    I’m sensitive to different grass pollens, etc., but no correlation to any foods. It may be pesticides on the foods, but maybe not. It’s so amazing to me how our bodies are all so different.

  48. Afton says:

    Sarah linked to her article again on her facebook page today. Drives me crazy how many people just follow without doing any research or thinking of their own. It’s sad how they are willing to stop with green smoothies after reading one opinion. Green smoothies are so great it, it’s such a bummer to hear of people stopping them.

  49. Michael says:

    Hi Robyn,

    I have read all your blogs on oxalates and the effects when cooked and not consumed raw.

    I love my green drinks but can too much of it be bad. I mean is there an amount we should not consume. Can we over load our kidneys with minerals that turn into calcium even though it is all coming in raw form.

    I usually make my drinks with Chard, Collard Green, Spinach, Broccoli & a Berry. I add a squeezed orange to it and drink down.

    I buy about a normal grocery size serving for each of the items and consume all this in blended form in 3-4 days.

    I was drinking it in a week now due to the flu season I am consuming them in 3-4 days.

    So can that be too much. How much is too much. One thing I realized i need a variety of drinks and not just the same cause that has been my drink for the last year almost.

    Thanks for your response. Appreciate your knowledge as always

    1. Robyn says:

      Michael, I suppose you COULD overload yourself with minerals, depending on other factors like health problems / weaknesses, and other toxic things you are consuming combining with minerals. However, that would be rare. You can go on extended green-smoothie detoxes as long as you’re getting good fats with your green smoothies, and a good VARIETY in your greens and fruits.

  50. Diana says:

    Oxalates, according to raw foodist Victoria Boutenko, accumulate if you eat the same green every day. You must vary the greens and you’ll have no problem with them whatsoever. Also only leafy greens should be used with fruits that contain soluble fibers, such as: bananas, berries, pears, mango and some others (to avoid unpleasant taste and indigestion). Some veggies, such as carrots, cabbage, onions, soy, beans and others contain sugars that are hard to digest, which give you gas. They should be steamed (beans should be soaked overnihgt) to minimize that effect..

    I’m drinking smoothies every once in awhile now. Every time I do it, I wish I would do it more often – that’s how good I feel.

    So in conclusion: vegies are more than capable of making you sick, if used wrong. But they are also the best medicine and fuel for the body if used properly.

    1. Robyn says:

      Diana, Victoria does say this, but she doesn’t offer any evidence. For the concept itself, nor for the idea that rotating greens obviates the problem.

    2. Robyn says:

      Diana, Victoria does say that, but she offers no evidence for either the oxalate buildup or the idea that rotating greens obviates that problem. I would like to see the evidence.

  51. Beenthere says:

    I think there may be too many people out there who make blanket statements about what’s good for EVERYone. Please! We are individuals, all different and distinct. Not many single rules apply to each and every one of us! I have been helped enormously by a low oxalates diet, but I don’t ever try to tell anyone it is necessary for them also! The same applies to green smoothies or anything else. It’s a bit like religion… we think we are on to a good thing, then try to foist it on everyone else as a ‘must do’. Why not put your ideas out there, and say “try it – it works for me, it might help you.” I have had great relief from recurring thrush, vulvodynia, cystitis, fibromyalgia, burning mouth and throat, infections, foggy brain, low energy levels and more – all of which have dogged me for many, many years (I am 61). I had always eaten and enjoyed lots of greens and fresh vegies, whole grain wheat and rice, soy… all the things I thought were healthy for everyone. They were, in fact, causing my problems, all being high in oxalates. It was a shock at first, but it has been a lesson in the ‘uniqueness of the individual’ to me. I had to rethink my whole framework of what ‘health’ is! There are still quite a range of fresh fruit and veg I can eat (including some greens!), so I’m not going to die of bloat or lazy bowel!
    So please – back off the harsh generalities and let us explore health as it meets each one of us in our own situations!

  52. Thank you for this article! I was appalled at Sarah’s article when coming across it randomly..

  53. Ralph says:

    Dr. Caldwell Esselstyn,author of “How to Prevent and Reverse Heart Disease” makes the following statement:

    Smoothies – How about smoothies? I love them!

    Avoid smoothies. The fiber is so finely pureed that its helpful properties are destroyed. The sugar is stripped from the fruit, bypasses salivary digestion and results in a surge of glucose and the accompanying fructose contributes to inflammation and hypertension.

    I also love smoothies and, although I have found Dr. Esselstyn’s diet super helpful, I was puzzled by the above. Thoughts?

    1. Robyn says:

      Ralph, Dr. Esselstyn has made a great impact on the world and I usually agree with him. But how is the sugar stripped from the fruit? Is he referring to JUICE? Very different from the green smoothie I refer to. Fiber is still in the smoothie, and very frankly the primates and those with undamaged strong jaws break their food down to a very creamy consistency before they swallow……so, again, this doesn’t make sense to me. I haven’t seen him quote any actual evidence of this. How can getting 10-15 servings of raw greens and fruit be inflammation-causing? Show me the data and I’ll consider it. A quote is just….a quote. 🙂


    2. Dan says:

      The idea that green smoothies – with banana’s, fresh fruit, spinach, greens, etc. can do any harm to you is absolute ignorant rubbish. If you grew all of that stuff on a farm and that’s all you had to eat – you’d be lean, healthy, full of energy, and live to be 100. Your stomach is a blender. So make all the smoothies you want, drink them, and let all the dumpy, out-of-shape, malnourished, ignorant opinionators who wish they were you blow their smoke.

    3. I also think the good Doctor has mistaken juicing for green smoothie blending. How could anything enjoyed raw from such healthy ingredients ever be considered bad for you.

  54. nativekitten says:

    I never put greens in my smoothies, I just have fruit smoothies daily as well as a salad that has a host of different vegetables.. I was one that did not do well adding greens to my smoothies, in fact they made me ill..

  55. Emily says:

    Victoria’s article on why we should rotate our greens and her response to the article “How Green Smoothies can devastate your health”, with lots of scientific research
    Go girls!

  56. Trimble says:

    I stumbled onto Sarah the Healthy Home Economist site yesterday and was stressed to the max after reading her article you’re referencing. I give my boys green smoothies daily and I was freaking out about the spinach issue. Thank you a million times over for putting my mind at ease by addressing the specific issue. Also, thank you for all the other greens you suggest because I really was at a loss of what I should be using besides kale and spinach. Seriously, I can’t thank you enough. I will sleep so much better tonight (and many more nights to come).

    1. Robyn says:

      Trimble, search on my site about this. It’s an ill-considered opinion not worth your time, but find my writing on it. GSG is searchable.

      1. Trimble says:

        Thank you!

  57. cheers says:

    I just want to say something if I can. People freak out all the time on the oxalate issue so hopefully I can explain what I have researched and experienced. A normal healthy person can perfectly digest oxalate. In fact, we have a specific bacteria in our gut called oxalabacter formigenes, look this up I encourage you to do your own research. But these bacteria are fragile and anaerobic so once we lose them they are near impossible to get back and there is no supplement with them for us to take. Antibiotics and poor diet/stress weaken the immune system. This is the killing off bacteria that lives in our gut. The bacteria gets low and there is a hole that forms called leaky gut syndrome. Oxalates are now able to pass through the GI tract and leak into the body. The body is forced to store them and try to pee the excess out but there is too much. So the key is to heal the gut and go on a low oxalate diet. We might never get back the oxalabacter formigenes but by increasing the other bacteria strains we can from fermenting foods and cutting out simple sugars we can very well have a chance to fix the underlying condition 🙂 but it takes a very long time

  58. cheers says:

    And it is not just greens that contain high levels of oxalates. Nuts, seeds, potatoes, and chocolate are a few foods that have high oxalate and are not greens.

  59. Jessica Goodway says:

    Solid article! My fiance and I are vegans for ethical reasons, and I was mildly surprised that dropping the eggs and dairy didn’t really improve my energy, skin etc. as I thought it would (although I no longer get food cravings!). I am hoping that drinking green smoothies will help with that. I came across the article about how devastating vegetables are, and, being a skeptic, I searched further, and you’re article is far more convincing and seems to have some actual, you know, facts. Good job!

  60. Dave says:

    Each of the last 3year around Christmas, I started a 30 day nutribullet greens and fruit smoothly. It is strange that around mid March to April, I get kidney stones.This time, I went to a Encronologist and mentioned that I was doing green smoothies. They did a 48 hour urine test, and they did a test on my stones and it showed that my stones were made up of oxalate.

    1. That is certainly a cause for concern and there is a rare person who has that reaction to foods with oxalates. Thanks for bringing this into consideration.

  61. So glad I found this article, because I was getting nervous as I read other articles about the harmful effects of oxalates in foods since I consume 1-2 green smoothies a day. I also regularly recommend them to my massage clients and friends. The science behind what the doctor says make so much sense. I am sticking with that!

  62. Fabiola Paco says:

    Hi everybody, do you know how much smoothies we need to consume daily. I don’t want to over do it. Thank you

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