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Phytic Acid in Rice Reduced 96% with Accelerated Fermentation

Please catch up on all the soaking grains research for the scoop on phytates, phytic acid, phytase and more!

I’ve been looking for another “real scientist” to balance the Great Debate between Sally Fallon and my Australian PhD contact. Imagine my joy when I stumbled across Stephan Guyenet, Ph.D. a Senior fellow at the University of Washington, Seattle, in the Department of Medicine’s Division of Metabolism, Endocrinology and Nutrition. He blogs about his studies of “time-tested strategies for achieving and maintaining health and well-being” at Whole Health Source.

Be still my beating heart! germinated brown rice Not only does Stephan know what phytates, phytic acid and phytase are, but he was willing to share his research with me so I could dig through the journal articles myself. In his post A New Way to Soak Brown Rice, he details the 96% effective method that I’ll share with you today.

New research from China in 2008 explored various methods of reducing phytic acid in brown rice. The trouble with brown rice is that although it is lower in phytic acid than other grains, it has a dismally low level of phytase, so soaking, even in an acidic medium, isn’t going to do much to impact the phytic acid. The authors of the study were able to reproduce some of the effects of sourdough fermentation on phytic acid in wheat by using a unique method for soaking their brown rice.

Termed accelerated fermentation, the process increases both natural phytase activity in the grain, and a sort of lactic acid fermentation, which also creates further phytase activity. I now have a little jar of soaked rice water in my refrigerator as a “starter” for my rice.brown rice results

SWN is soaking in water, and SWA is a soak in an acidic medium like Nourishing Traditions often recommends. Both are for a whole day. You can see in the chart above that phytic acid is reduced by less than half with both soaking methods, but almost down to nothing with the accelarated fermentation.

Here’s how it works:

  • Soak brown rice in dechlorinated water for 24 hours at room temperature without changing the water. Reserve 10% of the soaking liquid (should keep for a long time in the fridge). Discard the rest of the soaking liquid; cook the rice in fresh water. UPDATE: I reduce the amount of water added at this point. For example, if I have 1 cup rice and 2 cups water to soak, I pour off the water (reserving some) and add about 1 1/2 or 1 3/4 cup fresh water. You could be really precise and measure what you pour off, then add the same amount fresh to make up for what the rice has already absorbed. This makes a big difference in cooking nice rice! Don’t forget the rule of rice cooking – no peeking under the lid once you reduce to a simmer!
  • The next time you make brown rice, use the same procedure as above, but add the soaking liquid you reserved from the last batch to the rest of the soaking water.
  • Repeat the cycle. After three times, 96% or more of the phytic acid should be degraded at 24 hours.

Neutralizing and reducing that percentage of phytic acid is unheard of with other methods and grains. Even sourdough only decreases phytates by 64%. The modified fermentation acidifies the water and continues to keep the pH stable and even lowers it, whereas soaking in slightly acidic water ends up moving closer to a neutral (7) pH as time passes.

RELATED: Rice in the Instant Pot

The Point?

The goal of all this soaking and fermenting is supposed to be to reduce the levels of phytic acid in your grains so that minerals are more bioavailable and easy to assimilate into your system. After taking care to soak brown rice the third time with a bit of old starter water, the phytic acid is almost gone completely.

The sad news is that at the end of this research journal entry, the researchers found that zinc, the mineral in question for their study, was almost no more well-absorbed after the accelerated fermentation than it was before. They concluded that more study is needed; I concur and am left wondering if the work involved in soaking is worth it. There are other positive impacts beyond just phytic acid reduction, luckily.

Another way to reduce phytic acid in rice: germinated brown rice.

Source: Effects of soaking, germination and fermentation on phytic acid, total
and in vitro soluble zinc in brown rice by Jianfen Liang, Bei-Zhong Han, M.J. Robert Nout, Robert J. Hamer. a College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China

Posted at:

Unless otherwise credited, photos are owned by the author or used with a license from Canva or Deposit Photos.

62 thoughts on “Phytic Acid in Rice Reduced 96% with Accelerated Fermentation”

  1. Hi another question, Also wanted to confirm…

    so for each soak that we are reserving at least 10% liquid in a jar for continued use, when we pour that amount back into the new soaking rice each week, are we pouring 100% of the rice water back in OR still holding onto the original 10% from the first soak, that gets compounded with fresh rice soak water each week. So in other words, are we holding onto a compounded rice water that activates new rice water as it gets added and stored, or are we pouring rice water in and out of new soak batches, since each new batch has just a pinch more of “the original 10% batch” of fermented water


    1. Carolyn @ Kitchen Stewardship

      Add the entirety of the reserved liquid. So after each batch, you’re reserving a new 10%, which you then dump entirely into the next batch of rice you make. It’s not like a sourdough starter where you hold some back and use a little bit to activate. Does that make sense? I don’t completely follow the two options you’re describing, but I think that answers the point you’re getting at. Let me know if you still need further clarification. 🙂

  2. Hi, Question…. Should you freeze the fermented rice water after each new add or just keep covered in the refrigerator indefinitely?

    1. Carolyn @ Kitchen Stewardship

      Just keep it in the fridge. It should last a while and if it gets nasty because you don’t make rice for a few months, just start over again.

  3. Hi,

    Do you think it would still work/be fine to freeze some of the soaking liquid after the third batch if I don’t plan on making brown rice for a while?


  4. It says to soak in dechlorinated water, so why is that? Our city water has a tiny amount of chlorine added to it, and I haven’t been able to find an efficient filter to remove it. Can you recommend one? Or if I buy distilled water from the store, does distilled water have no chlorine? Thanks for the help!

    1. Carolyn @ Kitchen Stewardship

      Distilled water does still contain chlorine. I’ve read that you can add a small amount of vitamin C to neutralize the chlorine so maybe look into that. Here’s more about a water filter that does eliminate chlorine: Hope that helps!

  5. Hi,

    Do you have any thoughts on phytic acid in Lundberg’s organic sprouted brown rice?

    Also, since it is already sprouted, can I still soak it via the process you detail above?

    Thank you!

    1. Hi Katherine,
      Sprouting is supposed to reduce some of the phytates, but not all. See here for more info:

      I have not worked with commercially sprouted rice, but I would imagine the soaking process wouldn’t cause a problem. Try one cup your first time so the risk is low! 🙂 Katie

  6. It’s been studied that more phytate increases bone density which is what I need. So I’m very confused about this soaking business. For instance

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  8. Katie, have you come across any research about accelerated fermentation of rice and the absorption of contaminants such as arsenic? Your post predates the Consumer Report of Nov 2012, about high inorganic and organic arsenic levels found in rice. Logically, if phytic acid chelates zinc and other minerals it should also chelate arsenic and other toxic heavy metals. If we remove 96% of the phytic acid are we then absorbing more toxins too? This is an important issue to explore!

    1. Geri,
      I researched the arsenic issue enough to feel comfortable with eating rice in general, especially certain brands of organic rice that (I think?) tested their products for arsenic and were not as high as the report showed others to be. BUT this process likely won’t touch arsenic based on common sense, because it’s not chelating minerals, it’s releasing them from being bound up in phytate bonds, so a totally different thing. Soaking should increase the mineral absorption when eating whole grains and also neutralize the phytic acid’s potential effect on other minerals you’re consuming in the same meal. Thanks for the good questions, Katie

  9. I don’t see my message on this forum. Is it getting through? Want to know what’s wrong with using the same rice for all 3-4 soaks, instead of cooking/tossing a different rice batch each time.

  10. Still a little confused. After the first soak, why do I have to cook the rice? Can’t I just do the 3-4 soaks using the same rice I started with?


  11. hi, thanks for this. Following some research they recommend that you rinse rice at least 6 times before cooking and boil in lots of water to help eliminate any arsenic. I guess I could rinse first, then soak and cook? I’m even considering just giving white rice to infant as first grain, as may be easier to digest and lower levels of arsenic. Any thoughts?

    1. Alana,
      tough call on the first grain for infants…personally with our last baby and with the one due in October we withheld all grains of any kind until one whole year, and all gluten until 18-24 mos. So at that point I think it was rice or oatmeal, but I didn’t worry too much about preparing it any differently than I do for the rest of the family. Good luck! 🙂 Katie

  12. I have started soaking brown rice. But how do . Also consider arsenic factor. Do I rinse before I soak, and also cook in lots of water. I’m going to give rice to my infant as first grain. Any thought on soaking and eliminating arsenic

    1. Alana,
      Soaking, as far as I know, won’t do anything for arsenic. You have to buy rice that’s not contaminated. I think Lundberg might publish some testing results on their website? You don’t have to rinse but you may. I would definitely soak rice for an infant. 🙂 Katie

  13. Don’t want to get into the whole (pun intended) argument whether humans need to doctor their seeds. All I know is when I do take steps to reduce phytic acid, the rice seems more digestible, as the body has no gas reaction, compared to consuming rice prepared in the normal way.

  14. I have had trouble with my rice going bad. I live in Monroe, LA, and it is pretty warm in the house.

    I soaked a batch for 24 hours this week, and mold had started to grow on top. I was so aggravated! I used only water, no vinegar.

    Any suggestions would be appreciated. I’ve had plenty of times when the kids didn’t like the rice because the fermenting made it stinky, too. That was more when I was up north and was just starting.

    I’m wondering if there is a way to clean up my kitchen to kill of the spores!

  15. Hi, Could you clarify the instructions?

    Soak brown rice
    remove 10% of soaked water and keep in fridge

    Add that soaked water (why remove it then?) back to your next batch of soaking rice (why not the first batch you used to generate the rice water?)


    I am also not clear what you mean by repeat process three times..


    1. Hi Maria,
      You can’t add the previous water the first time because you don’t have any yet. So you soak rice in water, drain (save some) and cook it. Whenever you make rice next, you add the water from last time to this batch, soak, drain, save some, and cook the rice (with new water). Then you keep doing that – the “three times” just means that by your third batch of rice, you’re getting rid of most phytates, and that will continue from there on out. 🙂 Katie

  16. Sorry but I got confused with the three times.. could you clarify? You have to soak each batch three times? Three days? Or by the third batch?

    1. Katie @ Kitchen Stewardship

      Hello Rivkah!!
      The three times just means that by the third batch, you’re kicking 96% of the phytates. So like I just forgot to save the soak water from rice this week and had to “start over.” So I saved the water from the first batch, used some already this week in another batch. That rice is still “soaked” and healthier than unsoaked brown rice, and then next week if I make more rice with a bit of the water from batch 2, then I’ll be back up to 96% phytic acid reduction. 🙂 Katie

  17. Katie

    Still unclear on the accelerated fermentation process. So you reserve 10 percent of the rice soaking water. The next time you soak rice, you add this 10 percent to the new soak water.
    Now do you reserve 20 percent of the soak water, after discarding what’s left? After a third time, you reserve 30%?

    Thanks for your time.

    1. Dave,
      I truly eye it up – you save whatever you want, you just try to make about 10% of the NEXT batch’s soak water the leftover from the batch before. So I save about a cup every time and often my soak water is probably 30% old stuff, but eh, I’m not measuring! 😉 Hope that helps! Katie

  18. Hi. I soaked my brown rice for 48 hours instead of 24. The water was bubbly and even a bit smelly. I thought this was normal to have a slight smell. (Fermentation.) Somewhere in the thread someone said, “as long as your water doesn’t get smelly. ”
    I’m confused. Help! 🙂

    1. Gwen,
      True, some fermentation is “smelly” and this will have a bit of that going on…so you have to know/learn the difference between the fermented smelly and “yikes! this is a problem!” smelly. 😉 If there wasn’t mold on top, you’re likely ok. 🙂 Katie

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    1. N,
      Currently I use a Berkey filter which gets it all out, but most say that as long as your city water is chlorinated with chlorine, not chloramine, you can just leave some uncovered for 24 hours and it evaporates. That’s simple!

      (Sorry I missed your comment for so long; a few got totally buried and I’m just digging out!)
      🙂 Katie

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  24. Thanks for the article! I’ve been cooking with sourdough for several months now and am constantly amazed at how many health benefits there are to fermentation! It’s truly the way God intended us to eat bread! (Was brought to this conclusion after suffering when I made and ate homemade bread with bakers yeast – wow what a difference proper fermentation makes) I am interesting in making a rice culture and I’m wondering if I can use this culture when I want to soak oats, beans, nuts etc? Oats apparently have little or no phytase. Do you know if this is possible and how I would do it? I’m thinking that I would just want to save a little extra culture in the fridge after soaking my rice and then add some of that to my oats, beans or other grains while they soak- but not save the cultured water after using it for other grains… Any thoughts?

    1. Brandy,
      So sorry, somehow your comment was lost in the shuffle! I have never tried that – I’m not sure what it is about saving the water that makes it work. To add phytase to oats, just use freshly ground whole wheat or buckwheat (GF) flour – b/c rice doesn’t have much phytase either. Hmmmm….interesting theory! 🙂 Katie

  25. Hi,
    I have read so much about fermenting Brown Rice. Please anyone tell me why we have to throw away water after Fermenting Rice(Keeping 10% aside). Why cant we use the same water to cook that rice.

    1. Abhijit,
      I’m not positive, but a lot of traditional instructions recommend rinsing rice, which is somewhat like this. I would ask Stephan over at – he is the scientist who can answer questions like that! 🙂 Katie

  26. Is there any reason to follow these exact instructions but also add in yogurt/whey? I actually misunderstood and that is what I did. I’m assuming it doesn’t matter and since the water alone reduced the phytic acid so much on the third go around that is all we need? I am making rice for my 18 month old son for the first time and I want to make sure it’s easily digestible.

    1. Heidi,
      Yikes, so sorry I misplaced your comment for so long – I got way behind in August and never quite caught up. 🙁

      As for the whey, I don’t think it would hurt, but I don’t know that I understand the exact science behind the accelerated fermentation enough to comment on whether it would help or not…did your son do okay with rice? 🙂 Katie

  27. My experience with this method of ‘accelerated fermentation’ is not good. I tried it with brown rice, and with oats. It gave me digestive problems and made me unwell.

    If you want to reduce phytic acid in grains by soaking I recommend using rye/buckwheat instead with thea cid/salt/kefir method – I’ve been having rye porridge and it’s good; and if you want to reduce the phytic acid in oats, either just use the same method for the 20% or so reduction and then cook for a bit more, or go with baking for a 50% or so reduction(e.g. flapjacks, which can be made savoury as well). Or, just use the combination method, e.g. half rye/buckwheat, half oats.

    I can’t comment on rice, as I hardly ever have it anyway…

  28. Hi there. Thanks for this great post! I am not sure what you mean when you say “Repeat the cycle. After three times, 96% or more of the phytic acid should be degraded at 24 hours”. Are you saying we need to soak, cook, soak, cook, then soak and cook again, to degrade 96% of the phytic acid?

    1. Katie Kimball @ Kitchen Stewardship

      A good clarification! It means that you drain your rice and save the water. Cook that rice. The next time you have rice, whenever that is – could be a week or two later – you use the bit of water you saved as 10% of the soak water. Soak. Drain. Save a bit. Cook that rice. By the third time you make rice, you have a good “starter” worked up and it reduces 96% of the phytic acid. But you don’t do it multiple times on the same rice, no. 🙂 Katie

  29. Kate Sanford If your family doesn’t seem to have any heavy gut issues with unsoaked brown rice, perhaps it’s not something you need to worry about. There are other minerals beyond zinc that are bound up with phytic acid though. For those who choose to soak grains, this is the way to do it for rice. 🙂 Katie

  30. Kate via Facebook

    You say that ‘the researchers found that zinc… was almost no more well-absorbed after the accelerated fermentation than it was before…. I am left wondering if the work involved in soaking is worth it’. I love cooking real food for my family but you don’t really convince me that I really need to do this?!

  31. Marie Rogers Not necessary for white rice, because there’s no bran or germ and therefore zero phytic acid to contend with. 🙂

  32. Marie via Facebook

    I eat white rice, b/c it’s easier on our stomachs. I still soak. Would this be over kill for white rice?

  33. Marcee via Facebook

    I soak my brown rice for 2 days on the counter, using some of the starter liquid from the last batch.

  34. Jill Riley Powell You soak in broth at room temp? I do cook rice in broth sometimes, but I’ll still use this soak method, drain the water, and add broth, about 1/4 c. less per cup rice than I normally would because the rice has soaked up some water.

  35. Tiffany Guge It’s definitely “one more thing” to do the night before, but most of the time, it speeds things up the day of because half your stuff is already measured, so I appreciate that since my kids are always underfoot when I’m trying to get dinner started. I’ve also started cooking at least 3-4 cups of rice at a time and freezing it for easier meals later.

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