Greens and Oxalates

I get quite a few emails from people, expressing concern about the oxalate content of greens in green smoothies, in particular the action of oxalates in blocking calcium uptake in the body.

Oxalic acid/oxalates is certainly present in high amounts in greens – in fact it is present to some degree in almost all plant foods. Plants such as spinach, chard, silverbeet, beet greens, parsley, purslane, chives, cassava, amaranth, and rhubarb have significant oxalic acid content. Does this mean that eating greens is bad for your bone health?
Not at all.

While the oxalic acid present in plant foods will in fact inhibit absorption of some calcium, it does not block ALL of the calcium present in that food. Oxalates do bind to calcium and prevent the absorption, but this amount is very small, and the other abundant nutritional benefits of eating your leafy greens considerably outweigh the small decrease in calcium.

Basically, if you are drinking daily green smoothies then you are almost certainly getting far more than the RDA of calcium, and even with the oxalates causing a drop in levels, you will still come out on top! It is incredibly easy to meet the recommended daily amount of calcium (450mg) through your diet, and if you eat plenty of fresh fruit, vegetables, nuts, and seeds then you should be getting close to double that amount, since people who eat wholefoods diets tend to get closer to 700-900mg daily calcium from their food.

Anyone who is truly concerned about their calcium intake should consider adding sesame seeds and tahini (sesame paste) to their diet, since sesame seeds have an incredibly high calcium content – nearly ten times that found in full fat milk! These tiny seeds also contain a host of other crucial minerals and nutrients for bone health, plus the calcium in sesame is readily bioavailable.

Dietary choices that inhibit calcium absorption even more than the oxalates in leafy greens include meat, salt, alcohol, and processed foods – these should be excluded from your plate long before leafy greens get the boot, if you want to ensure that you are getting the full spectrum of vitamins and minerals.


3 thoughts on “Greens and Oxalates

  1. i eat a raw spinach salad almost daily. is cooking spinach to get rid of the oxalates better for my health? i have read elsewhere that steaming it lightly will reduce oxalates by 40%, and eating raw will cause kidney stones, irritate my mouth/throat/gut, depress my thyroid function….coincidentally, ever since i have started eating a raw salad daily, i have developed a phlegmy cough that just won’t go away even after a month. i began to wonder if this was truly due to the irritation from oxalates on my throat.


    • In traditional Chinese Medecine the phlegm you mention is categorised as damp and is a typical reaction to eating raw foods, particularly in cold weather!
      Save the raw salads for Summer or risk weakening your system.

  2. Hi Adelynn – Apologies, I missed your comment earlier! You can indeed lightly steam your greens if you are particularly concerned about oxalate content. I suggest that you mix your greens up a little rather than sticking to spinach alone – kale, chard, beet greens, wild greens, cavolo nero etc. are all great choices. I would be highly surprised if you developed a phlegmy cough as a response to eating a salad a day, rather it could be your body seizing the opportunity to heal itself and eliminate toxins from the body as a result of making healthier and cleaner dietary choices.

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