Backing it Up with Science – Can Green Smoothies Really Destroy Health?

I read (and commented on) a post over on Healthy Home Economist yesterday about oxalates (find it here). As of this writing, it is now the most-commented post on her site. While I was surprised and saddened by the outrage that was pouring out in the comments section, I was grateful to see that the post was making an impression on many. You see, if a post makes an impression, then people will remember it. Then, when they run into issues years down the line, hopefully some small niggling memory will remind them of what they read, and trigger an Aha! moment for them.

But I digress…What I wanted to do for that post was back it up with some science and numbers. Because the only valid criticism I saw among all the venom that was being spewed, was that Sarah had only cited one source on the WAPF (Weston A. Price Foundation) website for her information (and that source, when I checked it, did not cite any research to back up its claims). So I set out to do some corroborating for them. Please note that I am neither a medical professional nor a Registered Dietitian. I’m just someone who has had to learn a LOT about oxalates over the past couple of years.

Before I Jump Into the Science

First, though, I wanted to address some of the worries that cropped up. I think some people were skimming her article (or worse yet, just reading the headline), and not paying attention to the truly important information given in it. When she specified that 20% of people can have gut integrity issues which cause them to be susceptible to oxalate problems, the implication is that a whopping 80% of people DON’T have such problems. The trick is knowing in which group you fall. If you don’t know which group you’re in, for goodness’ sake, at least please pay attention to your body’s signals! While oxalates can easily sneak up on you, as they did on me, knowing that what you eat has an enormous impact on your health makes all the difference. It’s something that hadn’t yet sunk in for me (up until then I had always been able to eat almost anything with relative impunity), but I promise you it’s true.

Likewise, if you already know that your gut health is suspect (and for many folks who frequent Sarah’s site, I believe this is the case), then limiting your oxalate intake is a wise move, at least until you feel with some certainty that your gut is healed.

And a Bit of Refutation

Here’s the thing, I’m not totally agreeing with Sarah. She got a lot of things right, but she also got a few wrong. I can’t say why for certain, but it’s a fair bet that she may not have the latest testing numbers on oxalates available to her. For example, she warns against using most all leafy greens in your smoothies, including kale, which is particularly low oxalate (especially when compared to spinach). This is throwing the baby out with the bathwater, as you’ll see below.

Another thing I saw a lot of folks take issue with was her use of words like “large amount,” rather than specifying weights or measures. So let’s go with common sense: a serving is generally measured as a half cup. Since most green smoothies contain multiple half-cup servings of greens, her assertion of “large amount” makes perfect sense.

For reference, here are the oxalate values of a half cup of a few leafy greens (rounded to the nearest whole number), as per the latest available testing. A more complete list (with sources) is available via the TLO group, if you are desirous of such edification.

Leafy Green mg Oxalate per 1/2 cup serving
Raw Baby Spinach: 159
Boiled Dino Kale (raw values not available): 2
Boiled Mustard Greens (raw values not available): 3
Raw Swiss Chard: 175
Raw Arugula: 1
Raw Red Rib Dandelion Greens: 10
Raw Collard Greens: 4
Raw Romaine Lettuce: 1

As you can see, not all greens are created equal in terms of oxalate content! So it really pays to know which greens you can add to your smoothies on a regular basis without fearing their oxalate content. Of course, rotating and eating in season is also an excellent idea, and I have other issues with smoothies as well (I don’t think pre-chewing food is good, except in cases of medical necessity), but I do believe that the average American can use an extra serving of greens, so I’m not going to go to great pains to dissuade folks from getting it in this fashion.

Now for the Science

First up: “a high oxalate diet can contribute to some very serious health problems particularly if you are one of the 20% of people (1 in 5) that have a genetic tendency to produce oxalates or if you suffer from candida or other fungal challenge.” Who are these 20% of people? To be honest, I’m not sure where the WAPF got that specific number and their claim that it is a genetic variance, but I can find some studies that at least make it plausible when you add in fungal infections, as Sarah did.

As regards the genetic component, this study found that roughly .000015% of the population of the Netherlands has Primary Hyperoxaluria Type 1 (PH1). Granted, they aren’t representative of the world, but it does help me realize that we’re not going to get anywhere close to 20% of the general population with PH1. This study notes that there are only 24 patients noted in the literature as having Primary Hyperoxaluria type 2, so again, we’re not going to get our 20% from that disease either.

That leaves “candida and other fungal challenge.” Since this study managed to culture various candida species from oral swabs of 63% of middle-aged and elderly participants, I’d guess that finding a fungal challenge in 20% of the general population would be a fairly simple matter. And can fungi produce oxalates and release them into a host? Can they ever! This paper is one of many which demonstrates that rampant damage that aspergillus niger can do via oxalate crystal deposition.

Next up, let’s take a look at this sentence: “Oxalates can be deposited almost anywhere in the body and wherever they land, pain or worse is the result.” and the later “Oxalate stones can show up in any body tissue including the brain and even the heart.” with which more than one commenter took issue. It’s not the first time I’ve cited this study, but here’s the most striking evidence from it: “At post-mortem examination severe nephrocalcinosis, with widespread calculus formation and
deposition of oxalate in the myocardium, testes, muscles and bone, was demonstrated.” In case you’re not familiar, “myocardium” means heart muscle. I’ll admit I can’t find any peer-reviewed papers which cite hard evidence of oxalate deposition in the brain. However, it has been speculated that oxalate can cross the blood-brain barrier and cause issues. It’s also been demonstrated in vitro that rat brain cells have transporters for oxalate. If this is true, presumably tissue deposition in the brain would not be too great a leap, but I admit we need more science done on this. Problem being, most people with known oxalate issues aren’t going to be too keen on having tissue samples taken from their brains! So we sort of have to wait for people to die, AND just happen to have it be noted that oxalate deposition has occurred in other places AND have the examiner also check the brain for oxalates. A bit of a long shot, but I hold out hope.

How could these microscopic throwing stars NOT cause pain? - photo credit to NASA.

And pain? While I can personally vouch for the fact that oxalate deposition can cause pain, I imagine some will insist that I’m just a big baby, or better yet, “it’s all in my head.” (Yeah, I was told that by more than one doctor.) But can you deny the pain caused to so many kidney stone sufferers who have passed calcium oxalate kidney stones? For that matter, have you ever seen the shape of a calcium oxalate crystal? How could those tiny throwing-star-shaped things NOT be painful when lodged in your tissues? While the science isn’t yet there to support the anecdotal evidence (something which I hope to see remedied in my lifetime) let me guarantee you that oxalate, and especially calcium oxalate, is painful no matter where it lands – in skin, muscle tissue, joints…it all hurts. I even have x-ray evidence of a bone spur that developed on my spine during one especially prolonged oxalate detox (“dumping”) session. That one kept me awake many a night!

Here’s another bit I take a little issue with: “Given that the majority of people today suffer from gut imbalance/fungal issues caused by antibiotic and prescription drug use along with consumption of processed foods, a high oxalate diet which includes green smoothies is an unwise practice for virtually everyone.”

There is only a small body of evidence about this one, with this study among them. While this doesn’t provide support for her claim that “a majority” of us suffer from fungal issues, it at least acknowledges that such issues are rapidly increasing. Still, it has been my personal experience that many doctors don’t know about, much less look for, the fungal overgrowth which can be caused by antibiotics. Since antibiotic overuse is a known problem, though, I am hopeful that this will eventually become much more common knowledge. I only fear that if doctors DO become aware of it, they will see antifungal medication as the sole option, rather than allowing for natural, food-based healing as preached by Sarah and others.

What about the claim that “oxalates are extremely stable”? Well, we see they are heat-stable, and once bound to a mineral, do not readily dissolve in water. For all intents and purposes, this means that the oxalate which is in the food when it is harvested, will still be in it when it goes in your mouth.

In addition, as I mention in my article on soluble vs. insoluble oxalates, boiling can sometimes lower the oxalate content of a food, but not always. And you must also take into consideration that a boiled half-cup is generally much more dense than a raw half-cup, at least when it comes to leafy greens. So there’s no “getting away with” more spinach just because it’s boiled.

So Should You Really “Skip the Green Smoothies?”

In all honesty, I think the biggest problem with Sarah’s article was semantic – it did sound a bit sensational, but that is what makes it a good, attention-grabbing blog post. In fact, given how dry my own tone tends to be, I applaud you if you’ve managed to make it this far in my own article. :)

What I’ve posted above hopefully demonstrates to even the most hardened critic that yes, oxalates can be devastating to health. That doesn’t mean that they are devastating to everyone, in all cases. Knowing your own level of health and gut integrity is indispensable when determining how much of a given toxin your body can handle (and yes, oxalates ARE a toxin).

If you’re one of the lucky few with tip-top gut health (as well as your overall health), then an occasional oxalate-ridden treat is unlikely to cause any long-term damage. The real question, then, is how certain are you of your gut health? Does your gut have adequate stores of oxalobacter formigenes, or have you ever taken antibiotics (which kill this important microbe)? Do you have sufficient populations of other microbes shown to degrade oxalate? I encourage you to do your own research, and make your own conclusions.

Of course, it would probably be much simpler to stick with low-oxalate green leafies in your smoothies, and be happy with the health benefits you can reap from them. :)

Did I miss any points you’d like to see the science on? Feel free to leave me a comment and I’ll do my best to find it for you!

26 Responses to Backing it Up with Science – Can Green Smoothies Really Destroy Health?

  1. Thank you for the information and citations — I especially appreciate the list of leafy greens and their corresponding oxalate levels.

    Yesterday, a friend posted the HHE article and the alarmist headline caught my eye, caused me concern, and I read her article. Thankfully, I made it through to the comment section and found more information to help me balance her headline.

    We make green smoothies 2-3 times a week, and appreciate the reminder to rotate greens, use in-season veggies and avoid overdoing the spinach and chard.

    Thanks for your blog!

    • admin says:

      Hi Maria!

      Thanks for the comment, and for the encouragement! I am always happy to see other bloggers post about oxalates, as I truly believe that they affect more people than science currently acknowledges (especially considering the TONS of oxalate in the grain-heavy SAD). But I also hate to see folks getting poor or incomplete info on oxalates, as that could conceivably do more harm than good.

      I would think 2-3 times per week, as long as you’re using *servings* of greens (and not handfuls of spinach, like I did back in the day LOL), you should be fine and dandy.

      Thanks for stopping by!
      -Michelle

  2. Thank you for clarifying the issue, and for your thoughtful and kind response on my blog! I appreciate it, Michelle.

  3. Jodi says:

    Most *excellent* follow up. Great info, thanks!

  4. beth says:

    I also appreciated the information. Boy were people ready to string her up. Sometimes I think people just don’t want to hear any information that doen’t coincide with their own beliefs.

    • admin says:

      Hi Beth!

      I think you’re right; we’ve all been so indoctrinated into the idea that everything green and leafy is ideal for everyone, that it’s hard to fathom when someone comes along and tells us otherwise. The reality is that it’s an individual thing. I’m sure there are still a few folks walking around who could eat a pound of spinach every day their entire life, and never have any ill effects. If they have a perfect gut lining and perfect intestinal flora, and at least a dozen other factors going for them that I don’t, then they’d be just fine. But the reality is that even the most hardcore traditionalists among us have likely encountered pharmaceuticals and chemicals that our ancestors before us never had to cope with. And unless we’re hermits living in the woods, our bodies deal with this stuff on a daily basis. Why so many would castigate Sarah for bringing this information to the forefront is beyond me. As my mother used to say, forewarned is forearmed!

      -Michelle

  5. Mark says:

    red flags go up for me when ever someone sites extreme claims like Sarah did , “Stop green smoothies immediately” and yet offer no alternatives like leafy greens that are low in oxalates.. She makes it seem that all green smoothies are made up of nothing but foods high in oxalates. Alot of the green smoothies we make are made with the low oxalates and many recipes we have are of the lower variety. . A look into the the background of the material sited there is from the Weston A Price group. They spend very little time in helping to solve the the problem with the disease management system we are up against. Instead they continue to offer the biased solution as if their way is the only way to be considered. This only causes confusion and set back to the problem we are up against.

    • admin says:

      Hi Mark,

      I’m glad to see you delving further into this issue. One-sided presentations are rarely helpful, and can sometimes do more harm than good. Still, even in the internet age, I’ve found you must often visit more than one site (and sometimes many) to see all sides of an issue. It is such with oxalates; probably because mainstream medicine has for so long believed that the only problem oxalates can cause is kidney stones. Those of us who have come to the low ox diet (many in desperation) and found a piece of our puzzle know otherwise, but I am hopeful that the research will someday catch up with reality. For now we must content ourselves with baby steps, and drawing information from as many sources as possible.

      -Michelle

  6. Heidi says:

    Great response to Sarah’s post, Michelle! I agree that oxalate problems are more widespread and more severe than the medical and scientific community would have us believe. So many people spend years in pain, grief and misery before they figure out oxalate may be a cause of their problems (and some never figure it out). I also agree that erring on the side of caution and using low or medium oxalate greens is probably the best idea for most people. There are plenty of low and medium oxalate greens to choose from! At the very least, I’d urge people to become aware of the many oxalate-related symptoms and diseases, so if they already have a problem or begin to have a problem in the future they will have an idea of what may be causing it.
    Thanks again.
    Heidi

    • admin says:

      Hi Heidi, thanks so much for taking the time to stop by my blog, and thank you for the kind words!

      I sometimes feel like I’m preaching to the choir on this site, so I was happy to be able to reach a few new people with this post. I think the biggest problem is that there’s so much “propaganda” out there about how certain foods are healthy for everyone, when in fact every individual is different, and has different needs. While I realize oxalates are only one part of that puzzle, I’m convinced that they are a bigger part than modern medicine will ever admit. So I’ll keep preaching to whoever will listen, and hopefully word will continue to get out. Each day we reach a few more people – keep on fighting the good fight!

  7. Mario says:

    Thank you for your less frightening article on oxalates.
    Maybe you can add in the future, that in a healthy gut, the intestinal flora has some bacteria that digests and neutralizes the oxalates. So if people are aware of that they’ll find another reason to take care of their guts.
    The other thing is that less than 15% of the oxalates in kidneys come from the dietary oxalates.
    Protein intake, calcium intake and water intake are the most impoirnat concerns when we want to avoid oxalate kidney stones.
    The consumption of watermelon, organic cucumbers among other foods and herbs will help also to avid or get rid of the stones.
    Chanca piedra and hydrangea can help also to break the stones or prevent their formation.
    In terms of your comments concerning the “harsh comments” about Sarah’s article, I believe that judging is a violence that we do to ourselves first.
    Eeverybody visiting those websites has the good intention of learning or teaching, evn though some of them use the language in a way that provokes resistance. Let’s not add judgements to fuel their reactivity.
    Have a beautiful day.

    • admin says:

      Hi Mario, thank you for stopping by my blog!

      You are right, I should definitely plan a post (or perhaps even a series) about the ways we can fortify our guts against oxalates. Of course, a healthy gut is effective against far more than oxalates! But my mention above of oxalobacter formigenes, and its easy destruction by antibiotics, is probably less than an adequate discussion.

      I am very curious where this 15% number that I keep seeing quoted is coming from, though I see that George Mateljan mentions it in an article with a number of citations, so I’ll have to start digging there. My guess is that the study used some sort of marker to track ingested oxalate, but as anyone who has experienced the phenomenon of oxalate dumping will tell you, the diet is definitely not the only source for urinary oxalate – and that isn’t a good thing!

      I am fortunate to have not yet had any kidney stones, and part of my mission with this site is to raise awareness that kidney stones are not the sole indicator of an issue with oxalates. There are many, many other symptoms which are either caused or aggravated by oxalates. So I appreciate your mention of chanca piedra and other natural remedies for kidney stones, but I did want to remind my readers that not having kidney stones in no way indicates that you do not have an oxalate problem.

      Agreed on the judgements passed on Sarah’s blog. Alas, that seems to be a hallmark of the online world – when one can hide behind an alias, it is all too easy for them to behave badly. Let’s hope that in real life they are less harsh to their friends and family!

      Take care,
      Michelle

      • carol says:

        I am very interested in learning about ways we can fortify our guts against oxalates

        • admin says:

          Hi Carol!

          At this point, we have very little to go on as far as how to fortify the gut against oxalates. Now, if you’re starting with a good set of gut microflora, then probably the best measures would be preventative. That is, don’t take antibiotics! But if you’ve already taken a course (or several courses) of antibiotics during your lifetime, then it is likely that damage has already been done.

          Then there is the issue of leaky gut. From the looks of things, it seems that many people with oxalate issues also have a leaky gut. While this is a bit of a chicken-and-egg issue (which came first, the leaky gut or the oxalate problem?), healing a leaky gut is going to be a huge puzzle piece for folks trying to fortify their guts against oxalate.

          Basically, anything you can do to improve your overall intestinal health, will help you become more resistant to the effects of oxalate. One thing I would REALLY like to see some research done on is how fecal microbiota transplantation (FMT) affects folks with oxalate issues. I’d certainly be willing to volunteer to be a guinea pig in such an investigation!

          -Michelle

  8. Michelle: Thank you for sharing all your knowledge. Although Sarah’s article may have been overstated the good news is it brought this critical issue to the forefront. After battling Candida and other health issues for years – thinking lots of greens was a GOOD thing I am once again learning the “every food has a good and bad side” lesson. Can you point me in the direction of the best resources to get educated on oxalates? (sources, health issues, how to get rid of them)

    Thanks to everyone who had added information that will help a lot of people!

    MaryAnn

    • admin says:

      Hi MaryAnn!

      It’s amazing how hard some lessons can be to learn, isn’t it? It would be so much easier if we could just eat whatever tasted good, and not have to worry about nutrients, toxins and the like!

      While I can’t claim it’s the “best resource” on oxalates, I do have a section on my site for newbies, called “Start Here,” which can be found here: http://oxvox.com/start-here/

      That page is designed to step you through some of the most common questions folks new to the low oxalate diet, and even just the concept of oxalates, have. It will also lead you through the process of getting approved to the Trying Low Oxalates group, which is the best resource I know of, although it can be a little daunting to navigate at first. Essentially, I set up the Start Here section as a help to get folks into and functioning in the TLO group, because it’s such a valuable resource for everything you mentioned – knowing where oxalates come from, the health issues they can cause, and the steps to help you detox from them.

      If there’s anything you would like to see me add to that section or any other part of this site, please let me know; I always welcome feedback!

      Take care,
      Michelle

  9. Dipty says:

    Hi Michelle,
    I followed your article through Sarah’s. I love my green smoothie and was very defensive after reading her article. She did not give enough evidence to convince me to stop drinking my green smoothies. Nevertheless I read through all the comments to understand why someone can have such a radical opinion about green smoothie. That lead me to your site.

    Thanks for an excellent article on oxalate. I really appreciate you writing an article without any sensationalization. I now have a better understanding of the issue that affects so many people and why people are so polarized about this topic. And thanks also for giving a list of greens that are low on oxalate count.

    A question for you… what if you have your green smoothie, with baby spinach as the main ingredient (around 2 cups) and to it add 1/2 cup of whole yogurt? Would that lower the oxalate levels in the smoothie? Thanks a lot.

    • admin says:

      Hi Dipty! I’m glad to hear my article was helpful for you, and I appreciate your kind words.

      As for your question about putting whole yogurt into a smoothie with spinach, no, it would not lower the oxalate levels in the smoothie. I believe what you might actually be trying to find out is whether doing this would lower the bioavailable oxalate in the smoothie; that is, the oxalate available to be absorbed by your gut. While there haven’t been any studies on using yogurt to bind oxalate, it is generally accepted that calcium can bind oxalate in the gut and prevent it from being absorbed.

      According to nutritiondata.com, a half cup of plain, whole milk yogurt contains 137mg of calcium. So certainly, adding this amount of calcium would be better than NOT adding it. The problem I see is that two cups of raw baby spinach contain roughly 638mg of oxalates. So while adding some yogurt to the smoothie would likely help offset some of the oxalate in the spinach, spinach is such an oxalate powerhouse that it would take far more than half a cup of yogurt to try to offset it.

      That said, there still is no guarantee that the calcium would reach the oxalates before they are absorbed by your gut. So it’s sort of a nutritional game of chance to consume high oxalate veggies like spinach in any quantity, even if you consume lots of calcium with them.

      Hope this helps!
      -Michelle

  10. Michael Joel says:

    The article by Sarah freaked me out for minute until I came across this one. I’ve always been bad about incorporating fruits and veggies in my diet until recently when I started drinking green smoothies. For about a month now I’ve made a smoothie in the morning and afternoon with a cup of raw kale, a banana or apple, a scoop of vanilla flavored whey protein, and skim milk. I’ve also been eating raw broccoli as a snack during the day. I feel like my energy level has increased and I’ve shed a few pounds and I would like to continue this diet. By drinking 1-2 of these shakes a day am I setting myself up for kidney stones down the road?

    • admin says:

      Hi Michael! Sorry it’s taken me a while to respond – busy moving and all that!

      Will one or two green smoothies per day give you kidney stones? In truth, no one can say. What I would recommend is to not eat any one thing too often (including smoothies), and always pay attention to the signals your body is sending. Many folks (like my husband, for instance) believe that the body’s aches and pains are to be ignored or just lived with. Personally, I’ve found that almost every little pain can be traced back to one or another thing – too much of this, or too little of that, generally speaking. The important thing here (assuming you’re already in relatively good health) is to notice trends. For example, have you been drinking these smoothies for two months, and there has been a creeping pain in your joints that gets a little worse each week? Or perhaps, it’s the other way round – aches you’ve had for years have slowly gotten better. This is how I’d recommend you look for whether or not your smoothies are a good thing for YOU personally. This can be difficult, because we rarely change one single thing in isolation. But paying attention to your body’s signals, even if it is an inexact science, is worth a thousand times more than the random opinion of someone like me. :)
      -Michelle

  11. Ruth says:

    Not to be alarmist but-speaking as a former daily green smoothie drinker (for probably about 7 years), who started bleeding internally about a year ago for no apparent reason, I am feeling pretty anit green smoothies at the moment.:) One year later, after many hospitalizations and transfusions-and no help from the GI dr- I am managing the bleeding by managing my oxalate intake. The smoothies I make these days are not green. I will say the ones I used to make were probably much higher oxalate than most-almonds, turmeric, large quantities of parsley and raspberries, plus usually kale. I have not been able to eat raw kale without a stomach ache since the bleeding started. I had no digestive issues prior to the bleeding – that I was aware of.

    • admin says:

      Ruth,

      Wow, thanks for sharing your story! Have they determined what was bleeding or why? It’s so sad that many doctors are still completely unaware of the effects of oxalate on anything other than kidney stones. Keep fighting the good fight, and make sure to mention to every doctor that you see that you were helped by a low oxalate diet. If we keep educating our doctors, eventually we’ll make some headway!

      -Michelle

  12. Christina says:

    Is there a way to “test” to see if a person should go low oxalate. Or is it only based on symptoms? And, how can I find a resource on symptoms please? Thank you for your help and site!

    • admin says:

      Hi Christina!

      There are a couple of tests available. There is the Oxalic Acid urine test, but its reference ranges (and therefore its interpretation) have been said to vary widely.

      There is also an Organic Acid Test (OAT) available from Great Plains. That, in combination with an adjustment and interpretation by Susan Owens (owner of the Trying Low Oxalates Yahoo Group) may give you valuable information about your oxalate status.

      However, both of these can be costly. The least expensive method is to simply try the diet for a few weeks! As always, I recommend starting by eliminating the very highest foods you were previously eating first, and going from there. If you join the Trying Low oxalates Yahoo Group and download their spreadsheet, start with the foods marked Extremely High. Then move to the ones marked Very High and so on (if necessary) and see if it makes any difference in your symptoms.

      As for what symptoms may be indicative of an oxalate issue, I should probably put that list together, eh? In the meantime, I can tell you that the page which gave me the tools to put oxalate together with my own symptoms is over here in the Conditions and Research section of Susan’s original site.

      I hope you are able to find what’s causing your symptoms!
      -Michelle

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