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The Dangers of Green Smoothies (Can contain toxic levels of certain compounds)

By: Cat Ebeling, co-author of the best-sellers:  The Fat Burning KitchenThe Top 101 Foods that Fight Aging & The Diabetes Fix

Green smoothies and green juicing have taken the world by storm. Everywhere you look, there are green smoothie detoxes, and green juice powders, and green drink “cleanses”.

These green smoothies or green juices often contain a large amount of spinach, kale, chard, collards, arugula, or other greens.  Yes, we have heard our whole lives that we should be eating more greens, but the green juice/smoothie cleanse may have taken it a step too far. While a little may be good, too much is NOT GOOD.

As you have probably heard me say over and over again, “Eat REAL food”.  I have never been a huge fan of smoothies, shakes and juices. Real food is where it’s at.  I certainly don’t think our primal ancestors lugged a blender or juicer around during the day to blend up all those berries and greens they gathered. Nope, chewing is important, and it is necessary part of good digestion and good health.

Smoothies sound great, but since they are liquefied food, you generally end up consuming WAY more than you normally would if you were eating those things as solid food. What would fill a massive bowl as whole food, gets blended down into the size of a large drinking glass. There is often too much fruit, too much sugar, too many greens, too many carbohydrates, etc. All downed with a just a couple of gulps.  And as we’ll show you in a minute, there can also be TOO much of some problematic compounds in these green smoothies or green juices that you need to know.

So–how can a green smoothie be bad for me? It’s got everything good in it, right?

Yes, dark green leafy greens and cruciferous veggies can be powerfully healthy, and they contain a boatload of antioxidants like beta-carotene, lutein, and zeaxanthin and other fantastically healthy phytochemicals as well. They can help fight cancer, heart disease, diabetes, and obesity. These veggies also boost immunity by lowering inflammatory responses, reduce cell damage, and aid in digestive health too.

And yes, I know it sounds crazy for me to be cautioning anyone to watch out for overdosing on green vegetables, but the fact is, you CAN overdose on them, and many people are doing that without realizing it.

Spinach and other green leafy vegetables including chard, dandelion greens, kale, collards, beets, arugula and broccoli, all contain substances called oxalates. Oxalates bind to calcium and iron in the body and actually prevent the body from absorbing these important minerals. See more foods and oxalate content here.

What’s more, when oxalates bind with calcium they can create kidney stones, exacerbate painful gout, and cause other arthritic joint problems. Calcium oxalate is actually responsible for almost 80% of kidney stones. Oxalates can accumulate in the body and build up in the kidneys, causing serious problems, as was the case with this woman who ended up in the ER as a result of a green smoothie cleanse. Research shows that green juices and smoothies contain high levels of soluble oxalates and that drinking these green drinks too often can not only cause oxalate kidney stone formation, but even lead to renal failure.

People with certain inflammatory diseases including gout, arthritis, and even vulvodynia should avoid foods containing oxalates, because they can make those conditions much worse. Oxalates have been considered as playing a role in these diseases:

  • Thyroid disease
  • Vulvodynia
  • Calcium-oxalate Kidney Stones
  • Cystic Fibrosis
  • Sarcoidosis
  • Asthma
  • COPD
  • Autism

Excess oxalate can also lead to oxidative damage and the depletion of glutathione. Glutathione is one of the most powerful antioxidants in the body, and works to optimize liver function, helping to metabolize environmental toxins that enter the body.

Generally, most people can break down and process reasonable quantities of oxalate in the digestive system and it passes out of the body through the stool. However, those who have Crohn’s disease, IBD, intestinal permeability, poor fat digestion, celiac disease, inflammation, prolonged diarrhea and other digestive disorders may not be able to process oxalates out of the body as efficiently. Antibiotic use also eliminates the necessary bacteria that break down oxalates in the intestines, so they can harmlessly pass out of the body.

Many diet and health ‘specialists’ promote green smoothies or green juicing as a detox. And unfortunately, as is the case with smoothies and juices, you can over consume green leafy veggies, because you’re ingesting WAY more than you could if you had to chew them up and eat them as a whole food. And over consumption of even healthy foods like greens can actually bring on kidney failure, as in this case of a green detox gone bad.

According to this handy reference guide, a high oxalate intake is defined as consuming 250 mg oxalate per day. But a mere cup of raw spinach contains around 656 mg oxalate, and some people are using several cups of spinach and kale in these smoothies and juices, which is a massive quantity of oxalates. So, you can see how easy it is to consume too many oxalates in one glass of green smoothie or green juice!  Especially if you were doing a detox and having two or more green smoothies or juices a day.

Another issue with eating—or drinking—too many cruciferous vegetables like kale, collards, arugula, broccoli, cabbage and bok choy is that these vegetables can pick up a heavy metal mineral called thallium from the soil they are grown in. Thallium, for some reason, tends to concentrate in cruciferous vegetables, even if there is not much in the soil. This means if you happened to be eating an overabundance of cruciferous vegetables, you could be overloading your body with this toxic metal as well. Overdosing on thallium can cause strange symptoms like patchy skin issues, hair loss, arrhythmias, nausea, diarrhea, peripheral neuropathy, foggy thinking, digestive issues and more.

A molecular biologist, Ernie Hubbard, found similar symptoms amongst many of his health-conscious clients who were experiencing bizarre reactions that did not seem to fit any type of disease pattern. After a thorough investigation, he was able to trace their problems back to thallium toxicity from an over consumption of cruciferous vegetables.

There is one more issue with cruciferous vegetables. Cruciferous vegetables, which include the ever-popular ingredient, kale, contain compounds called glucosinolates, which inhibit iodine uptake by the thyroid. Iodine is a very necessary nutrient for thyroid health.

These goitrogens, as they are called, have been scientifically studied and are known to interfere with proper thyroid function. An overabundance of cruciferous vegetables (especially raw) in the diet can actually decrease thyroid hormone output, resulting in a hypothyroid situation. Hypothyroid symptoms include weight gain, hair loss, lack of energy, sleepiness, depression, anemia, and decreased immune function.

What Does this Mean — Avoid Greens Altogether?

Use organic veggies if you are making green smoothies—and don’t overdo it! As mentioned above, too many green smoothies can defeat the ‘detox’ part of a cleanse. Cut back or rotate the green leafy vegetables with high oxalate content to limit the oxalate levels you are taking in.

Opting to eat your greens and cruciferous veggies in their whole-food form is probably the best and healthiest option. You get the nutrient qualities of the greens without overdoing it and causing an overload of any other unwelcome ingredients. Chewing whole foods, as in a salad or side dish, is the best way to eat any food, not blended and masticated as juice or a smoothie.

Final Thoughts

Overdoing ANYTHING—even a good thing, can be bad, whether they are green smoothies, detox cleanses, juicing, etc. Green smoothies and green juices can contain too much thallium, oxalates, and goitrogens.

Smoothies of any type are a concentrated way to gulp down way too many calories, too much sugar, and too many other undesirable ingredients as well. A ‘detox’ diet of green smoothies or green juices may actually overload your body with toxic substances. Smoothies in any form are a concentrated way to drink down a massive amount of calories, and as you can see, a whole lot of other stuff too.

Veggies can be an awesome thing to have in your diet, and I still recommend you include a good portion of multicolored vegetables in your diet—as whole foods.

While you cannot avoid oxalates in green leafy vegetables, be sure to choose organic vegetables to reduce the amount of toxic metals such as thallium, and toxic residues. Conventionally grown spinach and kale both contain high amounts of toxic pesticide residues.

Certain types of beneficial bacteria in the gut actually help to break down and process oxalates in food. Supplementing with probiotics and fermented foods that contain Lactobacillus rhamnosus, Bifidobacterium animalis will help to break down and prevent oxalate buildup in the body.

Just remember, too much of any kind of good thing can go bad.

[Mike’s note:  Although some people seem to do fine eating leafy greens, I personally discovered about 3 years ago that leafy greens did NOT agree with my body, and was harming my digestion.  I probably ate a leafy green salad every night for 15 years and never questioned it, because everybody tells you to “eat more veggies”, especially leafy greens.  

However, whenever I tested eliminating the salad and focusing my meals more on meat, starch, avocado, and cooked veggies, my digestion would dramatically improve, I would have no bloating, and would feel better overall.  My bowel movement the next morning would be much better too when avoiding leafy greens.  Then, I would test adding leafy green salads back into my daily meals, and my digestion would suffer again…including bloating as well as a bowel movement the next morning that was excessively loose.  So I FULLY removed all leafy greens from my diet 3 years ago, and it was the best thing I’ve ever done for my digestion.  The more I talked to other people, friends, Naturopathic Doctors, etc, I kept finding time and time again that there are a lot of people that don’t digest leafy greens well at all, and do better with cooked veggies and roots like carrots, beets, and sweet potatoes.  As a nutritionist, I can say with 100% certainty that there is NOTHING “essential” about eating leafy greens… we can get every single nutrient we need from other foods like non-leafy veggies, fruits, nuts, meats, eggs, etc]


Even though we just talked about the dangers of TOO much juicing, and the ill effects a toxic overload can have, and how important it is to CHEW your food, it’s still obviously a wonderful idea to get your vitamins, minerals, and other nutrients from varied sources, but let’s be honest… that can be difficult. It’s even tough for me at times to get all of the nutrients I need from diet alone, so, I’ve partnered up with my friends at the Patriot Health Institute to give you 7 FREE packs of their delicious drink, Patriot Power Greens, which is NOT high in oxalates.  These make great “excuse busters” because you can literally take them anywhere, and make great additions for travel (which is where I typically use mine). All you have to do is click the link below…




About The Watchdog

Mike Geary has been a Certified Nutrition Specialist and Certified Personal Trainer for over 15 years now. He has been studying nutrition and exercise for almost 25 years, ever since being a young teenager. Mike is originally from Pennsylvania, but has fallen in love with mountain life and now resides in the picturesque mountains of Utah. Mike is an avid adventurist and when he’s not spending his time skiing, mountain biking, hiking, or paddleboarding on the lake, he has enjoyed skydiving, whitewater rafting, piloting an Italian fighter plane (seriously), scuba diving, heli-skiing, and traveling all around the world, enjoying learning about different cultures. At the age of 40, Mike now feels healthier, stronger, and more energetic than when he was 20... All because of a healthy lifestyle and great nutrition!

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  1. Love the article! When i started juicing , a couple of blood vessels in my hand popped and i felt awful and weak. My doctor told me i had juiced too many varieties and started with way too much way too fast. I stopped juicing and started making smoothies instead. I have a very sensitive body so i’m still learning what works and what doesnt. I must say, your article really helped me to understand why juicing just doesnt work for me. Thank you! I was close to ending up in the hospital and all because of juicing.

    • Romaine Lettuce is very low in oxalates and a good source of vitamin A, and sort of for folate and vitamin C. It has several amino acids too. Can’t go wrong with salads with Romaine lettuce everyday.

  2. I am not sure if I agree entirely with this article as I do know many people who blend kale and sea salt, like a type of Sauerkraut but ‘drunk’ whilst the enzymes are still very much alive. They have ‘cured’ themselves of Crohn’s disease by doing this and many others have reported favourable health conditions. The problem is that the antibiotics taken do indeed destroy the good and bad bacteria in the digestive system, once this is achieved the nutrients that one is consuming are not fully realised by the body.
    We need to go back to our roots and realise the gut/immune pathway, as with everything in our body as is with the universe, they are all interlinked and should not be treated as separate systems. It is important that even with juicing to ‘chew’ the food in your mouth for awhile, get the saliva fully mixed in. Take time to enjoy your food.

  3. My husband actually passed a kidney stone at a concert after having had a daily green smoothy with kale and spinach….
    The Dr. told him to go light on/ eliminate the greens! Too many almonds can do the same thing…..

  4. never understood the smoothie craze, we were not designed to ingest only/mostly liquid food, but our fast paced society of course welcomes “eating” your veggies in liquid form, no need to chew (though you should chew your liquids). Juicing and liquid food should not be the norm but used for times of illness, fasting, detoxing, in short not for a lengthy meal replacement strategy. We tend to overdo every thing…. either or, not finding a balanced middle ground. BUT that is just MHO.

  5. The article lumps kale with spinach as harmful because of too much oxalates, yet the linked table of oxalate content shows spinach to be hundreds of times as high as kale! Kale ranks quite low.

    As for chewing, the machine chews it up far better than I can, making more nutrients available, which is important since modern farming has depleted out soil so badly, and on the average, food grown today only has half the nutrition of what we had 50-75 years ago.

    As for iodine uptake, you ought to be supplementing iodine anyway. The tiny bit that’s in iodized salt is woefully inadequate, according to Dr. Brownstein and other experts in that field.

  6. Part of my decades long success consuming smoothies is that I quickly realized that putting fruit in a smoothie twice a day amounted to a lot of sugar. I now add only locally available fruit when it’s in season, the same sugar consumption level of our ancestors – except for those rare seasonal honey finds. By the time I learned to cut back on fruit I also learned about the pitfalls of oxalates, phytates and lectins. Since I went green about a decade ago I never put raw spinach or chard, the two culprits with the highest levels of oxalates, in my smoothies. Lacinato kale is actually quite low in antinutrients, so I add it raw occasionally, especialy the younger leaves. If I do eat other cruciferous vegetables I steam them lightly to remove the most of the antinutrients before adding them to my smoothie.
    True enough, our ancestors didn’t have blenders, nor do I. I use an immersible wand, it doesn’t blend as fine so my smoothies remain chewy. For those of us with digestive issues, predigesting food in smoothies is a boon.
    Our ancestors did, however, grind many things together and cook them. I can walk a short distance from my farm and find holes in rock formations where ancient tribes used hardwood poles to grind all sorts of food products together to prepare as soup. Soup, which has been eaten for countless millennia, is just a hot smoothie.

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