Is Kale Low Oxalate?

by Heidi on May 25, 2012

Is kale low oxalate?

Curly Kale - the most common variety of kale. Notice the curly, crinkly edges.

Kale causes more confusion for low oxalate dieters than any other vegetable.  So let’s clear the air and answer some basic questions about kale.

Q:  Is kale low oxalate?

A:  It depends.  Like a lot of vegetables, the oxalate content of kale varies greatly depending on the variety of kale and the cooking method.   A few decades ago, oxalate scientists tested some unknown variety of kale, using old, inaccurate testing methods, and determined it was high oxalate.  So, most low oxalate food lists on the internet (or handed out in doctors’ offices)  are out-of-date and list kale as high oxalate and off-limits (see Why Are the Low Oxalate Food Lists so Inconsistent for more information).  Fortunately, the VP Foundation added kale to their oxalate testing program in 2007, and using the new, more accurate testing techniques, found that a half cup of steamed kale is medium oxalate, and a half cup of boiled and drained kale is low oxalate.  The bad news is we don’t know which variety was tested!

Low oxalate dino kale

Dino Kale - notice the dark green, oblong leaves and the bumpy-textured "dinosaur skin."

In 2011, the Autism Oxalate Project tested curly kale and dino kale (lacinato kale).  A half cup of curly kale, raw, is medium oxalate (9.3 mg. oxalate), while a half cup of boiled and drained dino kale is low oxalate (3.5 mg.!).  We don’t know the oxalate content of curly kale when cooked, but presumably boiling curly kale will reduce the oxalate content just as it did for the unknown variety (boiling reduced the oxalate content for the unknown variety a lot!!!).  We also don’t know the oxalate content of dino kale when raw or steamed, but presumably it is higher than 3.5 mg. per half cup, possibly a lot higher.

So, is kale low oxalate?  Yes, if you use dino kale and if you boil it first.

Q:  Where do I get dino kale?

A:  You can buy dino kale at many natural food markets, farmers’ markets or mainstream supermarkets, especially when it’s in season (dino kale is a cool season green, which means it is grown in the fall or spring in higher latitudes and in winter in the lower latitudes).  You can also grow it in your own garden or in containers on your balcony or porch (buy dino kale seeds here).  I find it very easy to grow and harvest.  Plus, boiled greens like kale freeze well for use in winter soups.

Q:  The kale at my grocery store is just labeled “kale.”  How can I tell what variety it is?

Red Russian Kale

Red Russian Kale - notice the oak leaf shape and red veins (click on picture to see a close-up).

A:  Most of the kale in grocery stores will be one of three varieties.  The most common is curly kale.  It has a broad leaf with crinkly or curly edges  and a color that ranges from light green to dark purple (see the top picture).  You might also find red Russian kale (also called red winter kale) whose leaf is sage-colored with red veins and has a shape similar to an oak leaf (see picture to your right.) Red Russian Kale has not been tested for oxalate content.  Third, is our friend, low oxalate dino kale, which also may be called black kale, lacinato kale, Tuscan kale, nero kale, dinosaur kale or black palm kale (whew!).  It has a deep green, oblong leaf with a bumpy or “bubbly” texture that resembles dinosaur skin (see the middle picture).   Once you learn to identify the three commercially grown varieties of kale, you won’t have to worry about what they call it at the grocery store!  You’ll be able to pick up your reptilian-skinned greens and make a pot of yummy southern style low oxalate greens or chicken sausage soup with confidence.

Photo credits go to woodlywonderworks for Kids Harvesting Kale, tuscanycious for Kale and Nick Saltmarsh for Green Curly Kale.

{ 13 comments… read them below or add one }

Ruth Ann May 25, 2012 at 1:53 am

Thanks, Heidi. I’m so glad I found your website! I’ve been avoiding kale, but now I think I’ll try to find dino kale at my farmer’s market.

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Michelle Jones September 17, 2012 at 6:49 am

I have found websites listing kale as high in oxalate as well ad most greens. Please clarify the list of high oxalate foods.

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Heidi September 17, 2012 at 8:04 am

Hi, Michelle.
Thanks for your question.
Most low oxalate food lists published on the internet are incorrect. Please see my post “Why are the Low Oxalate Food Lists so Inconsistent” for more information. All of the oxalate values I publish on my website come from the most accurate and up-to-date testing available and are kept in a master list by Susan Owens (an oxalate researcher) at the Trying Low Oxalates Group. My post “How to get an accurate low oxalate food list” tells you how to become a member of this group and get your free list.

All of the values in this post are up-to-date and accurate as of September 2012.

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Carol January 6, 2013 at 1:18 pm

Boiling anything destroys nutrients and enzymes from what I have read esp in raw vegan sections. Steaming also better than boiling. So I want to understand here how one gains any nutrient value with this method beyond destroying Oxalates.

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Heidi January 11, 2013 at 3:08 am

Hi, Carol.
Boiling vegetables does destroy some of the nutrients and enzymes. But even boiled greens still contain lots of nutrients, enzymes, phytonutrients, antioxidants etc. You must decide for yourself if losing some of the green’s nutrition is worth losing some oxalate. Many greens are naturally low oxalate (see Guide to Low Oxalate Greens) and are commonly eaten raw or steamed by low oxalate dieters (some examples are cabbage, bok choy, kohlrabi, broccoli and lettuce). You may want to choose most of your greens from the low oxalate list so you can enjoy the full benefits of their nutrients in a raw or steamed state. I personally eat lots of raw and steamed greens, but I also enjoy boiled greens in soups or slow-cooked with onions and garlic. I feel like I’m still getting lots of nutrients this way and for me the trade-off is worth it.
Hope this helps.

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Diane Huff July 18, 2013 at 12:00 am

Are kale chips high or low oxalates?

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Heidi July 21, 2013 at 8:56 am

Hi, Diane. It depends on how you make them and how much you eat. I wouldn’t hesitate to eat kale chips made with dino kale and salt.

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Steven March 20, 2014 at 9:11 pm

It would be great if the low oxalate list would also list the Na or Sodium content on the oxalate list as kidney stones are often made of oxalate with calcium such as Calcium Oxalate stones. When there is excess sodium it pumps our water from the kidney back into the high sodium in the bloodstream which in terms raised blood pressure in anyone but also concentrates of calcium, oxalate and phosphorus in the kidneys which
in turn increases the creation of kidney stones. So the sodium which is all too present naturally and in foods is important to list along with a foods oxalate content. Also calcium is tricky as calcium can bind oxalate before it reaches the kidneys so the oxalate can’t get into the kidneys then but as intestinal waste and if they is too much calcium it ends up in the kidneys and if not enough then the oxalate increases into the kidneys instead of binding with calcium before reaching the kidney. So not only Oxalate, but also Calcium levels and Sodium levels, are also important to consider! The Low oxalate list is very helpful but it could be even more so if Sodium (and Calcium) could be listed too! (someday)

Sincerely
Steven

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Heidi March 25, 2014 at 12:43 am

Hi, Steven.
I agree it would be nice to have multiple health goals on the same list. The problem is everyone would have a different request for what went on that list! Almost everyone on the low oxalate diet has some other health issue or some other food issue they need to watch, and we are all so different. Amines, salycilates, SCD-legal, micro nutrient levels like calcium and phosphorus, macro nutrient levels like protein and carbs etc. For awhile the Master List Keepers tried to put more than one food issue on the list, but it got too difficult. We unfortunately must make our own lists to address our own health goals and challenges.
Heidi

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Lauren March 24, 2014 at 8:41 am

The kale I’ve been buying doesn’t really look like any of those. It looks like it might be dino kale but it’s definitely not that bumpy. Maybe it’s baby dino kale?

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Heidi March 25, 2014 at 1:00 am

Hi, Lauren. Thanks for your comment. Baby dino kale is less bumpy. Baby curly kale is also less curly. The big thing to look at is the edges of the leaves. If they are starting to curl, it’s probably curly kale. The leaf edges of dino kale can be really bumpy, but they don’t curl during any stage of growth. I grew some that was only moderately bumpy, not nearly as bumpy as the picture (though I often see it in the store that bumpy).

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Jen April 10, 2014 at 12:06 am

Hi. So, stupid question, but does baby kale have less than fully grown kale? I’ve been told I need to eat more leafy greens for one medical condition. However, I’m only 30 and have arthritis. I’ve found that it is worse if I’ve eaten a great deal of spinach. I need to find something that works with both conditions.

Also, if you don’t mind my asking, what is an acceptable amount of oxalates to eat each week? I’m not sure if the body clears these or not, but I’m feeling really overwhelmed with this issue.

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Heidi April 10, 2014 at 12:58 am

Hi, Jen.
No stupid questions here. Some immature forms of fruits (green vs. red peppers, green bananas vs. ripe bananas) have more oxalate than the mature form. This hasn’t been tested for any leafy green, however, so we have to estimate from the mature leaf’s amount.

People who suffer from oxalate toxicity usually need to stay below 60 mg. oxalate per week to flush their systems of the excess oxalate, but not everyone needs to go this low. If your issue is caused only by an over consumption of high oxalate foods, you might start there and just see what happens after a month of eliminating the highest oxalate foods (spinach, swiss chard, almonds, peanuts and rhubarb are some of the highest). If you still are having too much pain, you could cut back a littler further, etc. You should still be able to eat plenty of leafy greens, including kale, turnip greens, cabbage, arugula, mustard greens, collards, lettuce, bok choy and broccoli, just to name a few. I really love the traditional southern mix of collards, turnip greens and mustard greens. No need to ever touch spinach again!

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