Friday, April 29, 2011

Good news! Eating raw spinach might be OK after all

I'll say this now. I find it difficult getting to the bottom of what food is good to eat and how it's best to prepare it. 

I hear so much contradictory advice that often I don't know what to believe. Part of the problem is that food studies are not as straight forward as we might think; There are so many genetic, environmental and lifestyle factors that effect how people react to food. 

Sometimes I want to bury my head in the sand and just feed my family the status quo diet based on the "healthy" food pyramid. But I push on because I'd like to think my family is better off for my efforts to feed them well

You may recall that recently I posted a link to The Healthy Home Economist's article where she states that eating raw spinach, silverbeet and kale is bad for you because of its oxalic acid content. Her suggestion is to lightly boil or steam spinach and then discard the water to reduce the oxalic acid content. I've posted my technique for doing that here.

However, my friend Jessica Eccles saw my article and as she has access to medical journals through her university, was able to investigate this topic a little further.

What she discovered is cause for celebration. Here's what she says:

"I was just catching up on your blog when I read that you had stopped eating raw spinach because of what the Healthy Home Economist (HHE) said about oxalic acid. I looked at her blog to read more about it and look at her references. She references Dr. William Shaw and the book Nourishing Traditions. Shaw's assertion that, "Virtually everybody who eats a large spinach salad every day is going to succumb to kidney stones"[1] seems to be based solely on anecdotal evidence; a search of the pubmed database did not come up with any research articles by him on the topic. Unfortunately, I don't have access to Nourishing Traditions, so I wasn't able to see how well-researched that book is.

"Therefore, I decided to have a look at the current research myself.

"The research articles I found support some of the HHE's claims but do not support others and overall it looks like we can continue eating spinach (raw or cooked) without much danger that we will develop kidney stones or reduce our iron or calcium stores.

"The HHE says "[oxalic acid] also blocks iron and calcium absorption". Contrary to this, Bonsmann et al. found that oxalic acid did not influence iron absorption in humans[2]. Weaver et al. found that oxalic acid decreases calcium absorption in rats[3] but they also mention that "most of the human balance studies have indicated that spinach does not adversely affect calcium balances". Also, while oxalic acid inhibits calcium absorbtion it appears that calcium inhibits oxalic acid absorption[4].

"The HHE says "[oxalic acid] may contribute to the formation of kidney stones." However, a large prospective study by Taylor and Curhan[4] found "Oxalate intake and spinach were not associated with [kidney stone] risk in younger women. These data do not implicate dietary oxalate as a major risk factor for nephrolithiasis [kidney stones]."

"I also found a study about the effect of probiotics on oxalic acid absorption[5]. In this study it was found that probiotics reduced oxalic acid absorption markedly in people who naturally absorbed high amounts of this acid, and slightly reduced absorption in other people.

"From my reading, this all means that spinach won't affect your iron or calcium levels by much, and eating raw spinach probably won't increase your risk of developing kidney stones. 

"Even if you happen to be a high oxalic acid absorber, and therefore perhaps at a higher risk for developing kidney stones, it's still probably OK because the probiotics that you eat anyway from kefir, yoghurt, etc. will markedly reduce the absorption."

[this reference is here so that you can see for yourself that his research is not well referenced]

I've linked this post up to Healthy 2day Wednesdays.


  1. I love you for posting this follow up to the article lol! I'm one of those people who temporarily got paranoid after reading it! But thanks to a little bit of research also found misinformation in it, and can breath easy that I have a baby spinach salad almost daily:p Plus green juice once in awhile. Currently being on a raw food diet I was thinking, aww man I just can't get it right lol. But I'm healthier than I ever have been and happier, so life not affected ^_^

  2. Hi Anita, Thanks for your feedback. I'm so glad you've found the diet that makes you feel great!

  3. I really appreciate your posting this. I eat a spinach salad nearly every day and have never felt better, but got curious about whether I could be overdoing it. A Google search turned up that green smoothie post you mention, but after looking at it and the studies it references, I was a bit skeptical. Happy that someone with more science know-how than I have has taken this on -- it seems like it's always easier to be alarmist and reference popular, cult-ish sources like Weston Price's than to actually consult the scientific literature. So I just wanted to say thanks!

  4. Yay, I'm glad this article helped!

  5. Thank you for posting this! I will be forwarding it to someone dear to me who is not only misinformed, but has a big mouth. At least now I can fill it with some yummy raw spinach!

  6. Hi, I'm very interested by all that's been said, but also confused now! I'm 65 and suffer with gout, been trying different natural foods to ease myself off medication. This last week I've been eating a lot of raw spinach and now I'm getting a lot of pain from both sides of my kidneys? Coincidence?!? Any advice greatly appreciated. Novice in this field. JR. Leeds

  7. Any feedback on this appreciated...In the last week I have added greens to my morning smoothie (now a habit about 1mo old) which typically contains this: 2 oranges, or an orange and a grapefruit, 1cup greek nonfat plain, 1 pear or apple,sometimes a small greenish bannana, 1/4 cup of uncooked oatmeal, and 2 cups of raw spinach, a little lemon water.

    This all goes down real nice and I am good til lunch, where sometimes I will have another similar smoothie or a salad and some lean protein. Dinners are veg and lean protein. Weight is coming off pretty well. A long time drinker I have been off alcohol for 30 days and am likely going to up that another 30. Whole goal is to make friends with my liver again.

    Now I am reading this weirdness about oxcolates and spinach toxicty, etc. I just want to add some greens in my diet. Can I or can't I add a couple handfuls of spinach every day to my smoothies?


  8. Awesome, thanks for the great info!

  9. Still trying to figure this out. Also, there seems to be a lot of concern about drinking the water from boiled kale and a variety of other vegetables as well. I usually drink the water after boiling green leaf vegetables, but not sure if that is a good idea or not still.
    I really like my spinach, it makes me feel a lot better, kale also - just not sure about how best to prepare it in terms of all the concerns that I have been reading.


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