Saturday, 11 April 2009

Spinach And The Oxalic Acid Thing

Oh, don't we raw fooders love our spinach! It's usually up near the top of any poll of raw fooders' favourite foods, and, raw and cooked alike, everyone knows spinach is 'good for us'.

And it is. But there's one little 'spanner in the works' that pops up with some regularity on the raw food forums, and that's....the oxalic acid thing.

Oxalic acid is contained in many foods eaten by raw fooders, and 'significant' amounts have been found in spinach, kale, Swiss Chard, 'fat hen' (lambsquarters), watercress, purslane, parsley, beets, bell peppers, tomatoes, sweet potatoes, cabbage, cacao, nuts (eg almonds, cashews), seeds (particularly whole sesame seeds), buckwheat, some fruits (eg plum, starfruit, mango, most berries), some pulses, ginger. Wow - all those! So do we need to rule all those foods out of our diet? In most cases, no.
Oxalic acid has been shown to bind with calcium (and magnesium, iron, sodium and potassium) in the intestine, thus interfering with the absorption of these. And it's also been linked with the formation of kidney stones. Aargh!

So - do we need to worry...about spinach?!

OK. My throat always 'burns' when I eat Swiss Chard, which is my body telling me the oxalic acid in Swiss Chard is too high for me. It sometimes burns after beets. It's burned after spinach very occasionally (when mature/seeded), but for some reason only when blended or juiced (and not always). It's burned (lots) after black sesame tahini, but not after white sesame tahini (although made with whole seeds).

Now, to anyone reading whose throat doesn't 'burn' after these foods (the majority, I'm guessing!), I'm not going to claim that my body is 'cleaner' or more sensitive in any way than yours. It could simple be that, being an older woman, I'm being given a clear message to stay away from certain foods at certain times as I need all the calcium I can get! Those who have been following an all-raw diet for a while, who can be said to be reasonably in tune with their bodies' actual rather than perverted desires, who haven't experienced any such sensation from these foods, are most likely going to suffer no adverse consequences from continuing to eat them.

And, although my body does appear to protest against the oxalic acid in certain raw foods at certain times, many raw food experts feel that it's cooked, rather than raw oxalic acid, that causes problems:

David Wolfe ('Sunfood Diet Success System') says that the oxalic acid only binds with calcium in the body when it is cooked, and that this can lead to kidney stones. Although, he does go on to contradict himself slightly by warning readers to avoid even raw oxalic-acid-containing foods if they experience kidney pains hours after eating.

Tonya Zavaste also believes that it's cooked oxalic acid that's the issue. 'When cooked, it is not actually a nutrient in the body, so the body naturally processes it into the most convenient form to be excreted, usually through the urine. Oxalic acid will combine with other substances during this process and forms a salt known as an oxalate. Oxalates combine with calcium to form calcium oxalate. Kidney stones are 70-90% calcium oxalate.'

Indeed, Dr Gabriel Cousens ('Conscious Eating') says 'organic oxalic acid, defined as that which occurs in nature in its raw form (my italics), can actually be beneficial to the system.'

Natural Hygienist Nora Lenz says that oxalic acid is at a low level only in young or baby spinach but higher in mature spinach and other chewy leaves (which is what I've found).
And Dr Norman W Walker (the famous advocate of raw foods and juicing who lived to 99) explains why oxalic acid can in fact be a very good thing! He says that it is encourages peristalsis (the wave-like motions that push food through our digestive systems). Slightly contradicting others quoted above, he says that the oxalic acid in raw veg does combine with calcium, but that if both elements are in raw state 'the result is a beneficial constructive combination.' But he also warns that '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, again, thumbs up for raw, thumbs down for cooked.

I believe that 'instinctive eating' can come to our rescue here.

We should avoid foods that result in uncomfortable sensations in our mouth and throat. This may seem like common-sense, but, for example, have you ever felt a 'gritty', 'chalky' feeling in your teeth when eating certain foods, or shortly after them? Well, rather than saying to ourselves 'oh, it's making my teeth feel gritty', and continuing to eat, we should...stop eating. It's been suggested that this sensation is due to oxalate crystals leaking out of food as we chew. And if we do experience the 'burning' sensation in our throats, however mild, we should stop eating immediately, rather than ignoring it. When I last experienced it, in a spinach and banana smoothie, I ignored my body's messages and, being a greedy pig, drank the whole lot. That was daft.

However, if we do experience these sensations, my feeling is that we shouldn't over-react and 'ban' these foods wholesale from our diets. As I suggested earlier, it could be that our bodies are fine with them sometimes, but not at others.

Some advise 'rotating' greens just in case. To me, that all seems a bit complicated.

As well as simply stopping eating when we experience adverse sensations, I believe a more workable policy is simply to eat freely of foods when they taste good to us, and stop eating at the point at which they start to taste 'so-so', that is, when the 'instinctive eating' 'alliesthetic taste change' occurs that tells us we have had enough.

So, with foods such as spinach, we should eat as much as we like - the words 'we like' being key. Packing in tons of spinach when we really don't feel like it - because we've been persuaded by someone else we should - because it's 'good for us', because we're trying to meet a stipulated poundage/percentage of greens or whatever, is, in my opinion (following the principles of instinctive eating), not a good idea, as we'll likely be ingesting far more of it than our bodies actually want.

We should eat young leaves rather than old, tough leaves. Again, this seems like common-sense, but unfortunately raw fooders try to circumvent common-sense and dupe their bodies by chucking into the blender things their bodies would never have been naturally attracted to.

When we go raw, there's so much information, so much conflicting advice, so many dire seems that for just about every food there'll be someone saying we shouldn't eat it for this reason or that. This can make us feel unnecessarily anxious.

Provided we eat foods that we are genuinely attracted to, and in amounts only up to the point at which we are still enjoying the taste, only positive effects will result from our raw food diets. I have spinach at least every other day, sometimes consecutive days, and sometimes lots!
As a further comfort, consider this, from Dr Doug Graham: 'Typically, foods that have high oxalic acid also have high calcium. They buffer each other.' So, even if oxalic acid is affecting calcium absorption, that's outweighed by the fact that there's so much more calcium in spinach than the average vegetable in the first place that there'll still be plenty absorbed!

So, if warnings about oxalic acid have in any way put a damper on your spinach-eating, I hope this article has reassured. In general, we should continue to eat and enjoy raw, undamaged, young spinach for all the very good things contained in it!


luba said...

Debbie, thank you for your blog, very interesting and informative. I also was told that oxalic acid affects the thyroid. I've grown eating a lot of cabbage(fresh and fermented) because it was one of the few available vegetables for us in Moscow, USSR. Well, my thyroid is not functioning normally and I am on synthroid for more then 10 years now.
Any thoughts on this? Could the cabbage affect me that much? I am suspecting stress as a more important factor.
BTW, I am 50 also.Were you born in 1959?

Debbie Took said...

Hi Luba

I've been looking in my files for information on thyroid disorders.

Bear in mind that I'm neither a nutritionist nor doctor, but notes I've taken from my internet research on this say that acetic acid from fermentation leaches out the body's phosphorus and stimulates the thyroid gland, leading to hyperthyroidism. However, as you are taking synthroid, I'm guessing you have hypOthyroidism?

Also, one article suggested that cruciferous vegetables in general weren't great for the thyroid generally, although it admitted that studies were inconclusive.

I do have a little more information about diet and the thyroid that might be of interest to you. If you could contact me via the Contact Form at, I could pass this to you, but could you let me know whether the problem is hypothyroidism or hyperthyroidism?

(I was born in 1958 - older than you!)

Best wishes, Debbie

S said...

Synthroid is a synthetic thyroid supplement medicine used in the treatment of hypothyroidism. I have been diagnosed and under treatment for hypothyroidism for more than 30 years, and take natural, not sythetic thyroid supplement medicine.

Certain foods, including cabbage, brussels sprouts, kale, and other foods too numerous to name are recognized to interfere with the absorption of thyroid hormone, naturally or medically introduced to the body. I have been long advised by medical professionals to avoid these foods, else the supplement I take with not have the intended result, that is, the thyroid medical supplement will not be absorbed by my body.
I hope this information helps clarify your question(s).
There is an excellent book written on the subject of hypothyroidism that I recommend highly to anyone with an interest in understanding this disease (NOT a "condition", please).

Debbie Took said...

Many thanks for this info, S.

Purewishing said...

Great article, well thought and researched! I particularly liked the part about listening to your body. I would like to go raw, but struggle with the digestibility of the diet. Due to ruining my stomach with OTC and prescription drugs (naproxsyn sodium and sulfasalazine respectively), I can't tolerate any nightshades (tomatoes, potatoes, eggplant and peppers), cruciferous veggies, or those with high levels of oxalic acid like spinach without obvious joint pain. But also my stomach is so weak even something as simple as apples, oranges or a green smoothie with celery, blueberries, peaches, and oj will upset it. Any suggestions for easing into a raw diet with these restrictions?

Debbie Took said...

Hi purewishing

I like the way you're so realistic about WHY the raw diet is problematic for you, rather than, as some people will say, saying that the raw food diet will cause digestive problems per se. The smoothie you mentioned had a lot of ingredients (if I was understanding you correctly), and I never mix orange juice with other ingredients in a smoothie, as that can give rise to problems. How about starting with a simple banana-date smoothie each morning? This is my raw 'comfort-eating' - sweet and creamy!

xShelbyx said...

Great website!

Can u please post a typical days diet (times, amounts, foods)? Itd help a newbie out!

Also, does oxalic acid aggravate joint pain?

Debbie Took said...


I start the day with a green juice. Later in the morning I have a huge banana-date smoothie, sometimes with almond butter. After that I eat fruit, nuts, seeds, big salads, just as the fancy takes me.

Sorry, I don't know the answer to your query about oxalic acid and joint pain.

Kalinba said...

So very interesting things...I know that your article sort of goes back and forth between GOOD and NOT SO GOOD and I know that most research is like this but:

I eat GREEN veggies ALL THE TIME EVERY TIME for the past 2 years. Massive salads all the time: Kale (lightly steamed), Spinach Raw, Collard Greens (lightly steamed), Cabbage etc etc. BUT I MEAN ALL THE TIME. Plus of course other things in my salad.
So I understand things in the family of Kale and Spinach have Oxalic Acid + Calcium + Iron....but after reading about it I am sort of worried :((( I do not want to stop eating them or lower the amount. I mean what is out there to substitute with...some lettuce blaaaah :(

I want to have awesome Calcium and Iron absorption :)

What do you think?

Debbie Took said...

Eat your leaves raw, Kalinba.