Oatmeal is very popular as a breakfast food. However, few people know that oats contain many antinutrients, such as phytic acid. This article teaches you step-by-step how to soak oats overnight to reduce phytic acid effectively.
In addition, I use studies to show you simple but effective ways to reduce many antinutrients in oats.
Should You Soak Oats Overnight?
It would be best if you soaked oats overnight.
Oats are a grain, and cereal grains are seeds that contain antinutrients.
Oats contain phytic acid, lectins, oxalates, saponins, protease inhibitors, oligosaccharides, cyanogenic glycosides, and tannins (Alemayehu et al. 20211; de Punder et al. 20132; Önning et al. 19933; Kroslak et al. 20164; Korczak et al. 20135; Du Fall et al. 20116)
These plant chemicals block the absorption of minerals, vitamins, and proteins, damage the gut, cause digestive problems, bloating, kidney stones, and are toxic.
Plant toxins protect the seed and ensure the survival of the plant species.
Oats are exceptionally high in phytic acid, which prevents the absorption of iron, calcium, magnesium, zinc, and proteins (Sarkhel et al. 20227).
Moreover, oats are rich in lectins and saponins. These natural pesticides damage the intestinal wall, contributing to leaky gut syndrome and autoimmune diseases (Ferroli et al. 20128; Johnson et a. 19869).
Saponins can bind iron, zinc, and proteins, limiting nutrient absorption (Schoenlechner et al. 200810).
Oats’ protease inhibitors inhibit gastrointestinal enzymes that break down proteins into amino acids (Adeyemo et al. 201311).
The result is even poorer protein bioavailability and digestive problems.
Anyone wishing to absorb nutrients from a meal containing oats should soak them overnight.
In addition to increasing the bioavailability of minerals, soaking reduces toxins that can lead to inflammation in the intestines and blemished skin.
Does Soaking Oats Remove Phytic Acid?
Soaking can help reduce phytic acid in oats and oatmeal.
In nature, this antinutrient occurs as a salt (phytate) in all edible seeds, grains, legumes, and nuts (Gibson et al. 201012).
At 0.42-1.16 g per 100 g dry weight, oats are among the cereals with significant levels of phytic acid.
Too much phytic acid from the diet can cause digestive and concentration problems and bone loss.
However, the main disadvantage of phytic acid is that it drastically reduces the bioavailability of nutrients (Sarkhel et al. 202213).
For example, in a German study of vegan women, 42% of the participants were found to be iron deficient. The deficiency occurred even though they consumed more than the recommended daily iron requirement from fruits, vegetables, and grain products (Waldmann et al. 200414).
The most significant factor in this nutrient deficiency is the effect of phytic acid (Hunt et al. 200315).
The reduction of phytic acid is a primary reason why traditional cultures always soak their nuts, seeds, and grains and sprout or ferment them.
In the case of grains, soaking reduces phytic acid, thereby increasing the bioavailability of minerals.
Soaking in water at a temperature between 113 and 149 °F and a pH between 5 and 6 can reduce a significant percentage of phytic acid.
The main disadvantage of soaking oats is that minerals and water-extractable proteins are lost (Gupta et al. 201316).
Studies show that soaking oats may yield limited results.
How to Reduce Phytic Acid and Other Antinutrients
Soaking oatmeal cannot wholly neutralize antinutrients.
This method can be particularly effective when combined with another, such as cooking, fermenting, or sprouting (Shi et al. 201817).
For example, grains’ oxalic acid, phytic acid, and lectins can be effectively reduced (Noonan et al. 199918).
During germination, the plant hatches from the seed. This natural process takes a few days.
It can reduce antinutrients and increase the bioavailability of nutrients in seeds, grains, and legumes (Singh et al. 201519).
Malting is a controlled germination process applied to grains such as oats. Studies show that soaking and malting oatmeal reduces phytic acid and increases the bioavailability of iron and zinc.
However, the results are minimal. Compared with a conventional porridge, iron absorption from the soaked and malted oatmeal was increased from 4.4% to 6.0% (Larsson et al. 199620).
Thus, the combination of soaking and sprouting oatmeal is not ideal. So what is the best method to remove antinutrients from oats?
How to Soak Oats Overnight
Combining soaking, fermenting, and boiling is best to remove phytic acid from oats.
Brand new studies show that the fermentation of oats can reduce phytic acid to one-quarter (Mustafa et al. 202221).
For this reason, traditional cultures worldwide soak grains such as oats and allow them to ferment. This way, the grain gets predigested. Then, they cook the grain.
Even by conventional soaking in water, oats swell, and microbes set fermentation in motion.
It does not matter whether oats are soaked whole or in the form of oat flakes. However, soaking oats for at least 12 to 24 hours overnight is essential.
Only after eight hours does the grain start to swell correctly. If you soak oats not only overnight but over several days, the fermentation and reduction of antinutrients will be more effective.
Soaking oatmeal for 30 minutes does little, even though online sources recommend it. That’s too short a time to enjoy the benefits of fermentation.
Adding acid to jump-start the process can speed it up. Fermentation is initiated more quickly, making the oats easier to predicate.
Lemon juice, whey, sauerkraut juice, or active bacterial cultures, among others, are suitable for this purpose.
In addition to water or milk, milk kefir, water kefir, or even kombucha can be used to soak the oatmeal.
Like sourdough, lactic acid bacteria help break down starches and sugars in grains.
Organic acids neutralize phytic acid. Thus, prolonged fermentation with lactic acid bacteria can reduce phytic acid by up to 90% (Lopez et al. 200122).
Similarly, this increases the bioavailability of magnesium, iron, and zinc (Lopez et al. 200323).
Soaking and fermenting in kefir, followed by cooking, is the best method to reduce phytic acid in oats.
From a health perspective, it is still safer not to eat foods like oats that contain a variety of plant toxins.
Frequently Asked Questions (FAQ)
How long to soak oats to remove phytic acid?
Soak oats overnight for at least 12 to 24 hours to reduce phytic acid.
How much phytic acid is in oats?
Oats contain 0.42-1.16 g of phytic acid per 100 g dry weight.
Is it better to soak or cook oats?
It is best to soak oats for at least 12-24 hours and cook them afterward.
Is it better to soak oats in water or milk?
It is better to soak oats in milk kefir, water kefir, or kombucha than in water or milk.
Mag. Stephan Lederer, MSc. is an author and blogger from Austria who writes in-depth content about health and nutrition. His book series on Interval Fasting landed #1 on the bestseller list in the German Amazon marketplace in 15 categories.
Stephan is a true man of science, having earned multiple diplomas and master's degrees in various fields. He has made it his mission to bridge the gap between conventional wisdom and scientific knowledge. He precisely reviews the content and sources of this blog for currency and accuracy.
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Great article. I have a question, does one have to drain/rinse the soaked oat ? Considering people tend to advocate the “overnight oats” method in which you soak oats in milk or water and the eat the oat basically with the soaking liquid, I a have read that phytates tend to actually dissolve in the soaking water/liquid. Is this correct ?
Thanks for the appreciation, Louis!
Antinutrients do not fully dissolve in the soaking water. If you drain the oats, the result will be slightly better. However, as recommended above, adding acid like lemon juice to the water or using kefir instead of water will give you the best result.
I hope that helped 🙂
Br,
Stephan