Mineral Absorption Question from a Reader

Should we, as vegans, be concerned about the oxalic and phytic acid content of foods? I personally avoid eating rhubarb, buckwheat and starfruit, and only occasionally eat spinach, but it would be nice to know if my worries about mineral loss were accurate.

I would not worry much about oxalic acid as long as you are getting plenty of calcium and you are not prone to oxalate kidney stones. I think it’s fine to eat spinach every day.

Phytic acid is a more difficult problem for me to answer. My guess is that it doesn’t present that much of a problem for vegans, but I also heard that in the Vegan Health Study, Dr. Michael Klaper found that many vegans were low in trace minerals (I was not able to find anything on it in a quick Internet search just now). It might, therefore, be prudent to take a multivitamin which would most likely overcome any problems caused by phytic acid.

10 Responses to “Mineral Absorption Question from a Reader”

  1. Jeff de Vries Says:

    I’ve been concerned about the high levels of oxalates in typical vegan food items (dark leafy greens, beans, soy, etc), and the relationship to kidney stones. Is the key to maintain adequate calcium levels to counteract the oxalates? Thanks!

  2. Jack Norris RD Says:


    I’m not sure I know of any vegans getting kidney stones. There must be some, but since people do not regularly email me telling me they’ve gotten kidney stones, it is probably not prevalent in the vegan community. That tells me, there’s nothing to worry about unless you are genetically predisposed. The foods you mention tend to have calcium, so perhaps that’s why it isn’t much of a problem for vegans. In general, drinking lots of liquids is the best way to avoid kidney stones and I would focus more on getting enough calcium for good bone health rather than worrying about how much calcium you get for kidney stones.

  3. Lynne Says:

    Dear Jack

    Serious health problems for vegans (and others) eating “healthy” high oxalate foods over a long period of time often have no impact on the kidney at all.

    I am 55 years old and have always been a “healthy” eater eating lots of seeds, spinach,etc.. I became vegan about 10 years ago introducing foods i.e. soy, nuts. I recently developed an autoimmune disease (lichen sclerosis).

    My research into “LS” led me to discover the issues relating to oxalates being stored in the body. I do not have a medical background so would direct you to a couple of sites that are doing research into this because of oxalates links to autism, vulvar pain, etc.


    I would be encouraged if you supported this research as it is very difficult for vegans to reduce oxalates without the kind of knowledge you have.

    Kind regards

  4. Jack Norris RD Says:

    Hi Lynne,

    That’s very interesting and I don’t know much about it. It’s going to be awhile before I can look into it in depth and my sense is that there probably won’t be a lot of research in humans to look at. But I’ll put it in the queue!

  5. Bill Says:

    Yeah, it seems to me like everything I eat has high oxalate levels! and I am terrified of kidney stones. Here is a list of oxalate foods that I found…


    I eat tonnes of all that stuff! I hope that maybe you could comment further on this topic in new posts soon.

  6. Jack Norris RD Says:

    Hi Bill,

    I really don’t have more to say about it than what I’ve said above. In all the research on vegans I’ve seen (which is pretty much all of it), I have never seen kidney stones to be mentioned as a known problem, nor do I know of any vegans who, to my knowledge, have developed a kidney stone. I know some meat-eaters who have….

  7. TaVe Says:

    I’ve read that you can also take phytase to help reduce the amount of phytic acid.

  8. MichaelG Says:

    I know this is an old thread but I just commented on a more recent thread regarding phytate. First of all, it’s the phytate that protects you from kidney stones in the first place! Many references listed in the footnotes at http://www.uib.es/secc6/laboratori_litiasi/3inform/fitato/2Ang/fitatTa.html

    Second of all the jury is still out on whether vegans are any more likely to be mineral deficient than other populations. Those other populations aren’t having stellar results combatting osteoporosis either.

  9. Jack Norris RD Says:

    Just reread this thread and wanted to pipe in that, for the record, I now know of one vegan who has had a kidney stone.

  10. Jack Norris RD Says:


    This is a start:

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