Digestibility of Soaked, Sprouted and Fermented Grains & Legumes

Other posts in this series: Introduction to Fermented Cereal Week,, Phytic Acid in Grains and Legumes , Is Fermenting Grains Traditional? Phytic Acid in Nuts, Seeds, Cocoa and Coconut, Reducing Phytic Acid in Grains and Legumes

We all know that digestion is very important as most agree that our digestion needs to be good for good health. I noticed that many of the studies discussing reducing phytic acid through soaking, fermenting or sprouting also noted that it made the protein and other components of grains or legumes more digestible. So not only would you get more benefit from your food (such as more protein), but it could be a bit easier on your digestion as well.

The question is why it makes it more digestible.  As already mentioned, phytic acid inhibits enzymes needed for our digestion. If we reduce or eliminate phytic acid, those enzymes will be more available to us. That could be one important  factor why soaking increases digestibility. But I think that there is more to it.

Two Rat Studies…..

I found two studies highly interesting as they were done on rats. Rats produce much more phytase than humans (the enzyme that breaks down phytic acid), so they shouldn’t be as affected by eating raw grains and legumes. After all, none of us expect a rat to soak and cook it’s dinner before eating! However, when rats were given a soaked diet, the rats had enhanced digestion of their feed as well as improved absorption and retention of minerals and trace elements!  [i]

So even rats who have so much more natural phytase in their little ratty bodies benefited from eating a phytic acid free feed. I find that very remarkable. And I think points to the fact, once again, that reducing our phytic acid content could be quite helpful for us humans too.

In a separate case, they studied both by rats and amino acid analysis the effect of fermenting soybeans and wheat. They found that while the fermentation did not significantly change the amino acid composition of the wheat and soybeans,  rats fed the fermented wheat “improved” significantly and that the protein efficiency ratio was increased by fermentation. This may have been because fermented wheat is a better source of lysine. The mixture of fermented soybeans and wheat together supported growth with the fermentation process raising the protein efficiency ratio so that it was comparable to casein.[ii] So once again, rats fared better when fed fermented feed!

Another in vitro study found fermenting cereal gruels with a natural starter culture, had significantly improved protein digestibility. This was only not true for a grain developed to not contain tannins. So fermenting had a big impact on the digestibility of protein (it almost doubled the digestibility of the protein for some grains). [iii]

Sourdough Could Break Down Gluten

One interesting fact to keep in mind is that gluten (a component of some grains that many have trouble with) is a type of protein. Fermenting your grains will actually help break down this often irritating protein and make it more digestible. While I wouldn’t recommend that a true celiac eat any gluten grains, those of us mildly bothered by it or those of us who want to prevent building an intolerance may want to ferment grains for a better (lesser) gluten content. One study found that when a sourdough bread was made with wheat (and other non gluten flours) that it broke down the responsible reactors in wheat so that of the 17 celiac testers, none had reactions (though they did react to yeasted bread).  They concluded that fermentation was a “novel” tool (though I think it’s really an old fashioned tool!) for decreasing gluten intolerance. [iv]

Personal Experience

But beyond the many studies, personal experience is to be valued. While many handle whole wheat fine, many of those with more delicate digestion systems find that soaked whole grains helps their digestion significantly.
I remember making some seeded whole wheat rolls for my grandpa one time. He kept complaining about how “heavy” they hit the stomach. I realized that it was true, whole grain baked goods did often feel like a heavy stone in the stomach. Later when I started soaking my grains, I realized that soaking not only made the texture a lot lighter and more pleasing, it also took away that heavy feeling. Now that I am pregnant, my digestion seems a lot more sensitive. I find that unsoaked grain gives me bad heartburn, but that my homemade sourdough bread doesn’t.

Maybe it’s just me, but when I develop a recipe that works really well for soaking, I find that it’s texture and flavor so much more acceptable than regular whole wheat products. For example, both my biscuit and pancake recipes get comments about the finished product being light and not so heavy. Some even mention that husbands who don’t generally like whole wheat baked goods like this version. I just know it tastes better.

And why is soaked oatmeal so much more digestible?

Rolled oats is one grain item that is especially hard to reduce the phytic acid content as the phytase levels are generally destroyed. Yet despite the fact that many are probably not even touching the phytic acid content through soaking, many have discovered that they digest it so much better. I believe that this is because soaking helps “predigest” the grains so that your body doesn’t have to work as hard at digesting the grains. At least, that’s the only thing that I can think of! Once again, I notice right now that oatmeal gives me the worst heartburn right now unless I soak it. We have also found that soaked brown rice (which you will remember from my last post is very low in phytase) has a much more pleasing texture and hits the stomach much easier. I don’t know all of the reasons why that’s true, it’s just what we found.

Personal reactions to foods are hard to compile and put into a nice neat study, but I’ve heard and talked to many who feel that soaking grains have been a significant help for their digestive health. Many of you have recently left your own comments and experience with soaking grains in the comment section and I have found it very interesting and intriguing. Thank you!

Two Examples:

Katie @ Modern Alternative Mama shared:

Thanks for all the research and info! I have been working on this issue for awhile. However, my research has been primarily in how my own family is tolerating it.

We cannot eat unsprouted (or unsoaked) wheat or spelt. We note behavioral and digestive issues. Family members were labeled “gluten intolerant” and we did the gluten-free thing awhile. But I personally believe that a lot of those gluten-free things are not particularly healthy because they involve heavy starches and unsoaked gluten-free grains like corn and rice. Not so good.

Anyway, I experimented with sprouting. When only part of the grains sprouted, or when I let it sprout only slightly (1/8″ – 1/4″ tails), the effect was as if we were eating unsprouted grains. When I let it sprout “well” (1″ or longer tails!), we had no more issues. Now I’m experimenting with baking with it. Yeasted baking is challenging since the gluten is partially digested. I’m trying another recipe tonight that involves raw milk so we’ll see how it goes…it was LOOKING good!

Katie, I hope you update us on your success!

And Sandy shared:

I have been cooking with grains for about 9 years now but it wasn’t until the last year that i really began to understand and pursue proper grain preparation methods through soaking. Last winter my son and I were constantly suffereing from charlie horses/cramps in the middle of the night. Since it was cold, we started drinking an herbal tea (from Bulk Herb Store) with many wonderful herbs and noticed that our cramps stopped about the same time. As the weather warmed up, we stopped drinking our tea and noticed that within 1 -2 weeks our charlie horses came right back. Then I started getting more and more consistent with soaking grains and only made sourdough bread instead of the yeast bread that we normally ate. After several weeks of eating soaked grains, it occurred to me that my cramps had gone away. The only thing that had changed in our diet since the cramps had ceased was that we were eating a lot of sourdough (and soaking of other grains such as rice, etc). When I was driving in the car with my son I asked him how his cramps were doing and he said, “hmmmmm….you know I haven’t been having them anymore.” I immediately told him I think I know what it is but before I couldn’t finish my sentence, he immediately jumped in and said, “It’s the sourdough!” I was astonished that he came up with that on his own so quickly and asked him how he figured that out. And he said because the only he has had different in his diet since they went away was that we were eating sourdough instead of yeast bread. I don’t have scientific evidence that soaked grains are much bettern than non-soaked but for us that was enough for us to continue on the path of properly preparing our grains through soaking.

Conclusion: Personal experience and scientific studies seem to show that our food is more digestible when soaked. Some of us even notice a difference in our digestion personally when eating soaked grains (even grains where the phytic acid levels were not lowered). Just one more reason to follow traditional practices of fermenting grains!

Photo Credit

[i] Dephytinization of a rat diet: Consequences for mineral and trace element absorption, by torben Larsen, in Animal Physiology and Biochemistry, National Institute of Animal Science, Foulum

[ii] Protein Quality of Wheat and Soybeans after Rhizopus oligosporus Fermentation1 wa L. Wang, Doris I. Ruttle and C. W. Hesseltine esented in part at the Annual Meeting of the Federation of American Societies for Experimental Biology, Chicago, Illinois, 1967.2 This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture. Manuscript received 23 March 1968.

[iii] Lactic-fermented cereal gruels with improved in vitro protein digestibility, 1993, Vol. 44, No. 1 , Pages 29-36, Wilbald Lorri1 and Ulf Svanberg2 (http://informahealthcare.com/doi/abs/10.3109/09637489309017420?journalCode=ijf)

[iv] Sourdough Bread Made from Wheat and Nontoxic Flours and Started with Selected Lactobacilli Is Tolerated in Celiac Sprue Patients Raffaella Di Cagno,1, Maria De Angelis,2, Salvatore Auricchio,3 Luigi Greco,3 Charmaine Clarke,4 Massimo De Vincenzi,5 Claudio Giovannini,5 Massimo D’Archivio,5 Francesca Landolfo,3 Giampaolo Parrilli,3 Fabio Minervini,1 Elke Arendt,4 and Marco Gobbetti1 Applied and Environmental Microbiology, February 2004, p. 1088-1096, Vol. 70, No. 2

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I love beautiful and simple food that is nourishing to the body and the soul. I wrote Fresh: Nourishing Salads for All Seasons and Ladled: Nourishing Soups for All Seasons as another outlet of sharing this love of mine. I also love sharing practical tips on how to make a real food diet work on a real life budget. Find me online elsewhere by clicking on the icons below!

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  1. says

    Thank you! Soaking and sprouting is something I have just barely dabbled in, but want to explore more. I think that you’ve provided me the kick-start I need. I’m also fascinated by the science behind food. Great post!

  2. says

    Anyone have any good recipes for using soaked grains in a bread machine? I’m not very familiar with soaking grains, but I do have digestive issues and would love to pursue this!

  3. elaine says

    I really appreciate all the time and effort you have put into this. The amount of information is overwhelming and the fact that so much of it seems contradictory leaves me wondering what in the world to do! I agree – personal experience plays an very important role in this — we do much better with grains that are soaked or sprouted. I can’t wait to get my sourdough starter up and running and see how that goes! Thanks again!

  4. douglas says

    Does anyone know if fully sprouting a grain converts it’s nutrient profile from being primarily a carbohydrate to that of a vegatable instead. Do sprouts contain less carbohydrates than unsprouted grains?
    Also, can you actually make bread from sprouts when the original grain is so far gone?

  5. Andrew says

    Some great information – exactly what I was looking for. Thank you so much for doing this research. I imagine it has taken you a long time. It certainly saves us readers from the toils of research. I’ve just started to ferment my grains (quinoa, millet, oats), on recommendation from the Coop from which I buy them. I have Chronic Fatigue Syndrome with a whole host of symtpoms, including digestive issues. It’s too early to tell the impact and I don’t expect miracles (I’ve tried so many things). But I suspect it will have some impact, particularly with the absorption of nutrients.

    I ferment my grains by continually reusing the same fermentation water for each new batch. I wash the grain thoroughly, add it to the ferment water, and leave it covered for 24 hours at room temperature. I then cook it as normal. This produces a rather strong fermented taste, which I take as evidence that they have fermented well.

    I’m going to try this process with chickpeas as well.


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