Oxalates in Greens? Bad?

by Leisa on November 13, 2012

One question that I often get asked, is about the potential dangers of oxalates in greens. Oxalates are a plant chemical which has the potential to combine with calcium to form a calcium-oxalate stone. These are commonly known as kidney stones, and many people ask whether they should avoid leafy green vegetables, and other natural foods which are high in oxalates. Especially as I actively promote green smoothies as a wonderful addition to a healthful diet.

When I was reading what others have written about oxalates, I came across an article titled “How Green Smoothies Can Devastate Your Health” and I had to have a read! The article talks about the dangers of oxalates as if they are a given, and ignores the fact that there is debate among experts as to whether the oxalates in leafy greens contribute to calcium-oxalate stone formation or not.

I was preparing to write a blog post to refute the arguments raised in this article, and then I found one written by Kimberly Snyder that did just that, and she wrote it beautifully.

The post “Response to Article: How Green Smoothies Can Devastate Your Health” starts with this awesome opening paragraph: “Yes you read the title right. Though 2/3 of our population is currently considered obese, as people load up on high fructose corn syrup-filled sodas, deep fried doughnuts and fried chicken, pizza and fast food supersized meals…green smoothies can be the thing that can “devastate” your health?! Yes, green smoothies, that are made of raw green vegetables and fruit. As preposterous as this claim will surely seem to you, read on…”

Love this girl! Kimberly continues:

She then went onto describe the devastating effects this could have on health – ranging from fibromyalgia and kidney stones to oxalate stone formation in the brain. This type of fear-based, sensationalist nutritional information concerns me greatly, because it can keep people from eating the healthy foods their bodies need.

I totally agree. Aren’t there plenty of other foods to write negative articles about, other than leafy green vegetables? With our nutrient deficient processed diets leading to horrendous levels of chronic disease, how misguided is it to be writing articles about the dangers of the small amount of oxalates found in leafy greens (and other natural foods), when the risk of oxalate related illness is very low? There are many other factors involved in calcium-oxalate stone formation, such as high animal protein diets and inorganic calcium consumption. Surely the focus needs to be on these factors, not scaring people away from a food group such as leafy greens which provide thousands of healthy nutrients – vitamins, minerals, phytochemicals, antixoidants and chlorophyll – as well as good levels of fibre.

I wholeheartedly agree with the conclusion that Kimberly comes to and highly recommend you read her full article if you have concerns about oxalates in your leafy greens.

Have you heard the negative stories about oxalates? Has it affected your consumption of leafy green vegetables? Do you agree with the first author, that green smoothies can “devastate your health” or find the response article by Kimberly Snyder to be more balanced?



Please feel welcome to leave your comment, feedback or question about this blog post below! If you would prefer not to use your own email address, just type in the box below to post your comment. We'd love to hear from you!

4 commentsAdd comment

Eileen collins November 21, 2012 at 9:50 pm

Thanks for that as I have been aware of the oxalates in greens particularly in silver beet but not in spinach and was advised to blanch the silver beet but not the spinach.Cheers and bestwishes from Eileen and hope to catch a another course next year.

Sue January 7, 2013 at 2:32 am


I did a course of the green smoothies and unfortunately, co-incidence or not I did get a kidney stone. The pain was extraordinary and I didn’t know what the problem was at first as I was throwing up constantly. Then I got incredible back pain and not unlike labour cramps and I was in agony and I went to hospital.

There is no history of kidney stone ailments in our family and I rarely get sick. The only thing that I had done for over 2 months was regularly have spinach smoothies with spirulina, fruit etc.

When I recovered, I was trying to work out how i came to get kidney stones. I read information about spinach and oxalic acid and that this could cause kidney stones. It may be a coincidence but I will not be going anywhere near a ‘green smoothie.

That hasn’t put me off a raw diet, but I will be careful with the smoothies.

I didn’t want to put my full name in the Comment field.

Happy to discuss

kind regards

Sue Petherbridge

Leisa January 13, 2013 at 10:42 pm

Dear Sue,
Thank you for your comment and for sharing your very unpleasant experience of having a kidney stone. It is likely to be a co-incidence that you developed a kidney stone at the same time as doing a two-month stint of daily green smoothies – kidney stones can develop reasonably quickly (three months) when there are factors such as chronic dehydration involved, but normally stones take years to develop. There are four different types of stones, so if you had yours analysed they would be able to tell you if it was a calcium oxalate stone or one of the other types such as uric acid , cysteine or struvite stone. The main dietary risk factors for stones are dehydration, increased sodium intake and increased protein or meat intake. There are genetic risk factors, although you said that no-one in your family has had a stone, so that may not be part of the reason why, but certainly if you are healthy overall, and eat well, then it is definitely worth investigating the cause further, as I’m sure you don’t want to go through that extremely painful experience again! However I would not be too quick to make the green smoothie association with the kidney stone without a lot more information about the type of stone it was, as forming an oxalate stone within two months is not considered a usual time frame – although that certainly can’t be ruled out…

It is also now coming out in the research that oxalates can be neutralised by good bacteria in the bowel, and that dysbiosis, or low levels of gut flora, may have an impact on the chances of creating a kidney stone.

If you find out any further information about your stone, then that would be of interest and definitely worth sharing with everyone.

Thanks again for your story.
Warmest regards,

eve May 7, 2013 at 5:16 am

Hi Leisa,

Thank you for the article above they’re most informative.

I am a little confused with the Iron and Calcium thing: Have I got this correct or please explain how it is –

Is it correct that eating an iron food you must avoid calcium intake at the same time because of zinc have to do with this too now im really confused.

I have for breakfast a smoothie shake made of:should I not mix these together:

Also I’ve suddenly got a lot of grey hair (early 40’s) and read that it means im low in COPPER. Now should I get a homeopathic Copper 30c to re-establish the loss – why would I be lacking copper??

Leave Your Comment


(Spamcheck Enabled)


Previous post:

Next post: