Thoughts on oxalic acid

Purslane, good king henry, new zealand spinach, cranberry hibiscus, rhubarb, taro, sorrell, oca..

Lots of plants in a permaculture garden are high in oxalic acid, and the internet has lots of claims that it can cause kidney stones or prevent your body from absorbing minerals. I have a diet high in these foods, (although I blanch them as much as possible) and have no negative health effects and normal iron levels. Just wondering if anyone has thoughts on this topic?

In my opinion, for most people, oxalic acid is not a problem. The issue I have heard of personally was when an individual was consuming greens with oxalic acid as green smoothies, resulting in high concentrations. I suspect if eating the whole leaf, you'll get full before you reach dangerous levels.

I think it's that if you're otherwise predisposed to them, like you have them in your family medical history, that oxalic acid can cause kidney stones. Also, many plants that are high in oxalic acid are also high in vitamin D, calcium, and other nutrients that can contribute to the formation of stones.

But if you're not naturally predisposed, and if you blanch everything, all the time, you aren't in a high-risk category. I find that the taste will also tell you. Unless your sense of taste is impaired, it will try to inform you that way, through impalatability, that eating too much of it won't be good for you, such as in the case of bitter melons, and unripe tomatoes, to name a couple.

-CK

I think blanching is key to eating greens high in oxalic which in bulk. I also think small quantities regularly raw is helpful.

As they say, the difference between poison and medicine is dosage. A small amount of oxalic acid from raw greens intermittently can help the body purge heavy metals.

Joylynn Hardesty wrote:In my opinion, for most people, oxalic acid is not a problem. The issue I have heard of personally was when an individual was consuming greens with oxalic acid as green smoothies, resulting in high concentrations. I suspect if eating the whole leaf, you'll get full before you reach dangerous levels.

Do you mean juices, where you strain the fibre from the juiced materials? That shit is about as healthy for you as drinking store-bought juices, I think. When I was doing green smoothies, I was blending 5oz of mixed baby kale and spinach with frozen blueberries and almond milk. They were invariably black. I loved them, and nobody else could drink them.

But there was no pulp. Everything I put in the smoothie I drank. I consumed those containers of greens whole, essentially, with some blueberries and almond milk for flavouring and liquid. I got all the fibre, soluble and insoluble, so the barriers to digestion were largely still there, with the exception that some of the bioflavonoids were made more bioavailable.

-CK

Chris Kott wrote: Do you mean juices, where you strain the fibre from the juiced materials?

That is correct.

Ben, I come from a line of oxalate kidney stone formers and I noticed the same thing last year (my garden has sorrel, chard, kale, taioba, rhubarb, red hibiscus, etc). I had a "kidney event" last year and found some very interesting stuff out of University of Chicago about reducing risk by upping calcium intake (and reducing sodium). As it turned out, my kidney stones were left over from some years ago and my problem was something else entirely (who knew: stomach ulcers and kidney stones can feel remarkably similar), but the idea that adding calcium can reduce kidney risk was new to me (and reducing sodium is just good in general). You may find this interesting (fair warning: it's a rabbit hole) https://kidneystones.uchicago.edu/how-to-eat-a-low-oxalate-diet/

Here are links to a couple videos over on the non-profit website nutritionfacts.org looking at the latest science on oxalates in food.

https://nutritionfacts.org/video/Oxalates-in-Spinach-and-Kidney-Stones-Should-We-Be-Concerned/
https://nutritionfacts.org/video/kidney-stones-and-spinach-chard-and-beet-greens-dont-eat-too-much/

The bottom line takeaway I got from them is that eating excessive levels of high oxalate foods on a regular basis should probably be avoided, though even worse for kidney stone formation would be eating a diet high in animal products.

David Huang wrote:Here are links to a couple videos over on the non-profit website nutritionfacts.org looking at the latest science on oxalates in food.

https://nutritionfacts.org/video/Oxalates-in-Spinach-and-Kidney-Stones-Should-We-Be-Concerned/
https://nutritionfacts.org/video/kidney-stones-and-spinach-chard-and-beet-greens-dont-eat-too-much/

The bottom line takeaway I got from them is that eating excessive levels of high oxalate foods on a regular basis should probably be avoided, though even worse for kidney stone formation would be eating a diet high in animal products.

Could you elaborate on the animal product part? That's the sort of generalisation that makes some thinkers switch off. The excessive levels of oxalate being bad for you isn't really surprising, as too much of anything can be harmful, especially to the wrong person and/or in the wrong situation.

-CK

i think it's just a general extrapolation that protein load causes work for kidneys (which have to work to remove its byproduct, urea), the more protein the harder the kidneys work. Generally a low-protein diet is only recommended when kidney function is really critical, potassium and sodium are the first things to be limited. Meat has lots of protein, and when it's combined with potassium and sodium it's extra disastrous.
https://www.kidney.org/atoz/content/lowprotrecipes (the most neutral source I could think of).

In the event some readers are switching off thinking that I'm just a militant vegan let me say that while I do eat predominantly a whole food plant based diet (which is a subset of vegan) I am in no way a vegan.  I do eat meat and animal products from time to time and don't expect that to stop.  My dietary choices are being based more on the science than morality.  I'm not at all for CAFOs but think it's obvious animals belong in healthy permaculture systems.

My comment that a diet high in animal products would be worse for kidney stone formation was simply my takeaway from the videos I previously linked to which are presenting the data from scientific papers.  That is the goal of the nutritionfacts.org website, to just provide the data from the best scientific papers on nutrition, trying to weed out conflicts of interest, pointing out weak or flawed studies, and keeping the site itself free from any influences of advertising.

To dig into the question a bit more I found this other video Dr. Greger has produced about how to prevent kidney stones with diet.  https://nutritionfacts.org/video/how-to-prevent-kidney-stones-with-diet/  This one seems to focus specifically on animal protein and kidney stones so it might be more of what you are asking about Chris.  It's about 4 minutes long.  (note, the videos on the site are almost always short)  Like all his videos he shows the actual studies and there are links provided to the actual papers if you click on the "sources cited" button.

In this video he first presents data known since the 70's but based on population studies.  However, that type study can't really show cause and effect.  He then goes into later interventional studies showing that indeed increased animal protein intake to a level that is normal for the standard American diet causes a 250% increase in markers for kidney stone formation.  Also, it is specifically noted that it is animal protein that does this, not plant protein.  Here is the part he highlights straight from a study.  "Preliminary investigations have shown that the only dietary factor which is correlated consistently at all demographic levels with expenditure on food and the occurrence of stones is the intake of animal protein.  Conversely, in populations with a relatively high intake of vegetable protein compared with animal protein there is apparently a low incidence of upper urinary tract stones"

In this particular video he is referencing the data from 7 different studies.

This other 5.35 minute video on how to treat kidney stones with diet may also be of interest to anyone wanting to know more about all this.  https://nutritionfacts.org/video/how-to-treat-kidney-stones-with-diet/  In this one he gets more into the mechanisms involved in various stone type formations and how different diets relate.  Again, all the sources are cited under the same sources cited tab.  Some takeaway, though certainly not all.  A vegetarian diet can reduce uric acid crystallization by 93%.  Stone formation in diets high in animal protein are likely due to the high acid and purine loads these foods create.  Most stones are calcium oxalate which led most to assume a low calcium diet would be of most benefit until a study compared low calcium diets to that of one low in animal protein and salt.  It turns out the low animal protein and salt diet cut the risk in half compared to the low calcium diet.  Some types of stones can actually be dissolved (ie. cured) simply through changing the diet to one plant based likely as a result of the changes this makes in the PH load of the kidneys shifting it from acidic to alkaline.

I do recommend watching the videos to get all the info.  They are designed to give the relevant info quickly, again with sources available for anyone who wants to dig deeper.

Joseph hackett wrote:Purslane, good king henry, new zealand spinach, cranberry hibiscus, rhubarb, taro, sorrell, oca..

Lots of plants in a permaculture garden are high in oxalic acid, and the internet has lots of claims that it can cause kidney stones or prevent your body from absorbing minerals. I have a diet high in these foods, (although I blanch them as much as possible) and have no negative health effects and normal iron levels. Just wondering if anyone has thoughts on this topic?

Yes you should be concerned, because oxalates are far from causing only kidney stones!

You will not feel any negative effects until you reach the maximum capacity of your body to store oxalate. The best way to know if we have an overload is to go carnivore, because when our diet is oxalate-free, the body starts to dump the stores... Maybe not all at once, we are all different. But it happened to me! I had cloudy urine and neededs to pee more often, itching eyes and a brittle white plaque inside my lower teeth. After many months, I still have episodes of dumping...

Oxalate bind to minerals in our guts, calcium, magneisum and iron, lead and mercury too, impeding the normal excretion of these toxic metals! The bigger storage we have is 80% on our bones. Oxalate also damage our mitochondria and causes fatigue.

- If you eat dairy with your oxalate rich foods, it helps to not absorb.
(if you eat a lot of fat and don't digest it very well, it will bind to calcium and thus you will absob more oxalate)
- If you have good guts, no leaky gut and the right bacterias, it helps too.
- If you have had a mold issue or candida, you are more likely to have an oxalate issue too, because fungi make oxalate.
- Boiling and throwing the water helps, but minimally...

As we are very likely to have some issues making oxalate not safe for us nowadays, I find it wise to lower our consuming of oxalate rich foods, and increase our low oxalate foods. Then balance your sources.... If you really have to eat a local high oxalate food because you produce it, then lower other oxalate rich foods consumption!

If foraging, avoid the oxalis familly but also the amaranth and chenopodium familly.

So to your high oxalate foods, list you can add :

- amaranth greens and seeds
- lambquarters.
- Pokeweed
- Malabar spinach
- Spinach
- Chards
- Beets
- Quinoa and buckwheat are also of the same familly!
- Bamboo shoots
- grape leaves
- yams
- sweet potatos and most white potatoes
- Chocolate and all nuts are also high.
- Most beans too.

Now the low oxalate foods.

- All animal products.
- Fats and oils, but not their seeds.
- All coconut products (it is rich in sulfur)

Sulfur rich food = alliums and brassicas :
- garlic, onion, shallot, chives...
- cabbage, brocoli, cauliflower, swede, Brussel sprouts, chinese mustard greens, radish, daikon, roquette....
(the dino kale and the red russian kale are the highest)
- Watercress, garden cress, nasturtium.
- Coffee, which is also rich in sulfur.
- mustard
-

- The cucurbitaceae familly except bitter melon.
So melons and courgette and cucumber and squash and pumpkins...
- Chayota
- also their seeds! They are the only low-ox "nuts".

- cilantro and chives.
- Lettuce
- Endive and scarole
- Alfalfa sprouts, mungo sprouts.

- Celeriac
- Asparagus
- Sweet red pepper
- tomato
- chinese wild yam (cinnamon scented)


- Mushrooms

- Wakame
- Kombu

- Many fruits: apple, pear, nectarine, plums, grapes, cherry, lemon, mango.

- White rice.
Brown rice is quite correct too.
- Young RED peeled potatoes, if peeled and cooked and the water thrown away.
- Barley is medium.

- Bananas and cassava root are reasonable.

Reasonable if boiled and sliced for the roots, and the water thrown away:
- carrots and parsnip roots
- fennel
- artichoke

Higher but still correct for non sensitive persons:
- green beans
- sunchoke
- tomatillo
- celery, fennel and carrots, even raw.
- okra
- tomato paste
- green peas
- dendelion greens

https://s3.amazonaws.com/bioindividualnutritioninstitute/Handouts/16_Oxalate_Myths_Julie_Matthews.pdf

Interesting. I just came across a recent video looking into available research on this topic. https://youtu.be/Ppkwby3mehU
I'm going to continue eating a little bit of whatever I find to eat.

I remember reading that jack in the pulpit has alot of oxalic acid
and the best way to get rid of it is to dry it for a long time.
Around 6 months.

OK found it,.. Peterson field guide to edible wild plants.
Says it has calcium oxalate,..
Like skunk cabbage.
might not have the same properties as oxalic acid.

Finally some discussion concerning this issue. Been aware of my oxalate overload since a couple of years now, but many people reject or do not take this problem seriously.
Basically, after many years on a plant based diet, I accumulated unhealthy amount of oxalates. Being a vegan did it to me, but not overnight.
As a vegan I ate a lot of dark greens, chocolate (and trust me, many vegans are hooked on chocolate), and nuts, seeds,
I never eat spinach since at least 3 years, so funny that this leave is seen as super healthy food, whereas for me it is toxic. I really do not like it anymore. I also feel a distinctive aversion against beetroot, and I am not a fan of seeds, I really try to avoid them. And this since many years. It takes a long time to rid the body of it's oxalate, and it will take quite some time before you notice anything, it took me many many years of veganism before it realised about this toxic built-up.
Maybe it all depends on our pasts, some people having eaten only very little veggies in their life, will think that spinach should be eaten.
On my list, spinach is on top of the list of the worst foods for me.
I do still do eat veggies and a lot of fruits, I just choose wisely. And I definitely include more animal based foods.

Plants use oxalate (among other things) to protect their seeds, and lace their seeds with natural pesticides to avoid pests and predators. The sharp oxalate crystals can prick a predator’s mouth, and thereby playing a role in plant defence.

Plants also load the seeds with oxalate, as a way to store calcium for the offspring. When seeds start to germinate they split off the oxalic acid which frees the calcium for the small, growing plant.
So oxalate is useful as a calcium storage for plants, but it’s toxic to humans.

Oxalic acid grabs minerals, especially calcium and forms calcium oxalate – the main ingredient in kidney stones.

These oxalate crystals build up into bigger and bigger crystals, and as they accumulate the body deposits these sharp crystals in the body and the deposit are stored, and grow.

Spinach is a not a good source of calcium. It’s all tied up in oxalate. And this is true for all high-oxalate foods.

High-Oxalate Foods include seeds like, sesame and poppy seeds, soy, potatoes, okra, and sorrel.

Oxalate damage is from toxicity, it’s not caused by food sensitivity or an allergen.

as someone who is planning on getting most of their calories from yukon gold potatoes, should i be worried about oxalates? ill be eating lots of fish, duck, rabbit, pork and brassicas, and keeping oxalate containing salads to once a week tops. ill also be eating no dairy to counteract oxalates. no family history of kidney stones, should i be worried? also plan to eat lots of nuts and feed lots of raw chesnuts to my pigs.

C. West wrote:as someone who is planning on getting most of their calories from yukon gold potatoes, should i be worried about oxalates? ill be eating lots of fish, duck, rabbit, pork and brassicas, and keeping oxalate containing salads to once a week tops. ill also be eating no dairy to counteract oxalates. no family history of kidney stones, should i be worried? also plan to eat lots of nuts and feed lots of raw chesnuts to my pigs.

- Having good guts is the best prevention.
- Kidney stones are not at all the only possible issue with oxalates.

- Chestnuts are not high in oxalate.
- All animal products and all fats are low in oxalate.
- For sure eating some dairy with the highest in oxalate food was a traditional way to bind oxalates and not absorb them.
- Lactobacillus and some other probiotics "eat" oxalate. Oxalobacter too, if we have it... and it can be gone since doing antibiotics...

- Red skinned potatoes are known to be the lowest in oxalate.
- Peeling and boiling the cut potatoes + throwing the water removes a fair part.

- People with the issue can take Mg citrate or Calcium citrate during meals.
- Lemon juice is useful.
- if you need to eat a high oxalate food, just stay away from the other ones that are not important to you.
- Suppressing the very high ones such as rhubarb and spinach chards or oxalis and chenopodium familly is already great.

thanks xisca

There was a post in a kidney stones topic, worth adding here:

Jonathan Byron wrote:In stones made of calcium oxalate, the real problem is from the oxalate, not from the calcium. Moderate amounts of calcium is protective against oxalate stones, moderate amounts of oxalate in the diet increases the risk of stones.

Calcium with the food is a good way to reduce the amount of oxalate that gets absorbed into the body (and which must then be concentrated and excreted via the kidneys).  In this study, humans were given two types of chocolate with identical amounts of oxalate. The dark chocolate caused an increase in oxalate levels in the urine (higher risk), but the milk chocolate did not.
http://www.ncbi.nlm.nih.gov/pubmed/12563622

Spinach and some other leafy greens (amaranth, zuiki taro, etc) are particularly high in oxalates, and if you can't avoid them, eat them cooked with dairy. Spanakopita (Greek spinach pie) is a traditional food that neutralizes most of the oxalate with cheese. If you are vegan, a small calcium citrate supplement with a meal might be good.

Citrate is protective against stones; citrus juice, tomatoes, and other high citrate foods are good:
http://www.ncbi.nlm.nih.gov/pubmed/19911682

Tomatoes seem to be good:
http://www.ncbi.nlm.nih.gov/pubmed/20113185

Rosehips are another option:
http://www.ncbi.nlm.nih.gov/pubmed/21544885
Recent research on rose hips confirms that it can also help with osteoarthritis.

Also this one:

Susan Bradley Skov wrote:It's quite common, here where I live, to have a bottle of calcium chloride solution (calcium chloride, water and lactic acid) in the cupboard to add to spinach and rhubarb dishes. One uses 2 tsp. per kilo, either while cooking or afterwards, in order to neutralize the oxalic acid. I don't remember something like that being generally available when I lived in the US, but it might be worth checking. It doesn't seem to be used for raw greens, however. I don't know if it would have the same effect without heat.

A diet is considered low in oxalate when not exceeding 50 mg / day

List of the top high foods in oxalate:

Over 1000mg / 100g :
(I roughly put the highest first, but nobody knows why there are big variations, if it comes from the soil, the watering, the season, the stage of growth...)

- Whole sesame seeds
- Poppy seeds
- Seeds of Caraway, fennel, celery, ajwain, cumin, anis
- Lemon Myrtle
- Turmeric
- Clove
- Cinnamon

- Rhubarb
- Swiss chards and beets leaves
- Spinach
- Sorrel

- Indian gooseberry

500mg - 1000mg / 100g :

- Purslane
- Heart of palms
- Chia
- Red kidney bean

200 - 500 mg :
- Lotus root
- Bamboo shoots
- Chinese yam
- Job's tears seeds
- Bran
- Nopal
- Sweet Potato especially purple, next orange.
- Some potatoes, baked or deep fried.

- Almonds
- Cashew
- Sacha inchi
- Pine nuts
- Hazelnuts

- Star fruit (carambola)

- Black pepper
- Sage
- bunium bulbocastanum seeds (a black cumin)

100 - 200 mg :
- Amaranth leaf and seed
- Beet root
- Okra
- Raw fennel
- Burdock root
- Dill
- Basil

- Peanuts
- Brazil nuts

- yard long bean
- Hulled sesame and tahini
- Dried mesquite
- Buckwheat
- Wheat germ
- Oat bran
- Wheat
- Rye
- Teff
- Quinoa

- Mulberry
- Goji
- Boysenberry
- Dry fig

50 - 100 mg :
- Most potatoes
- Sunchokes
- Eggplant
- Plantain
- Parsley

- Walnut
- Hemp
- Pecan
- Pistachio
- Olives

- Mung bean
- white bean
- soy beans
- Pinto

- Fig
- Dried apricot
- Elderberries
- Feijoa
- Guava
- Blackberry  
- Black raspberry