Soaking can cause some soluble compounds to move into the water, but saying that 'soaking removes nutrients' is misleading. At the same time, soaking hydrates the seed, shortens cooking and reduces some oligosaccharides and antinutritional factors.
In other words, there is a trade-off: some soluble compounds are lost, while cooking time can fall and substances that affect digestion or mineral availability can also be reduced.
What happens during soaking?
When a dry pulse is placed in water, water crosses the seed coat and gradually hydrates the interior. This changes tissue permeability and allows some water-soluble compounds to move from the seed into the soaking liquid.
That is why soaking water can change colour and contain sugars, minerals and phenolic compounds from the pulse.
Are minerals lost?
A fraction of minerals can be lost through leaching, but the size of the loss varies greatly. Potassium and other soluble minerals can move more readily into water. Time, temperature, water-to-food ratio, variety and whether water is discarded all matter.
Soaking should not be pictured as 'emptying' a pulse of minerals. Soaked and cooked pulses remain nutritionally valuable.
What happens to vitamins?
Water-soluble vitamins can migrate into soaking water to some extent. Final losses depend on both soaking and cooking. An unnecessarily long soak followed by prolonged cooking in a large volume of water can cause more loss than a process adapted to the pulse.
Protein and fibre
Most protein remains in the seed. Small quantities of free amino acids and soluble nitrogen compounds can enter the water, but soaking does not remove the structural protein of the pulse.
For fibre, studies describe changes in the balance of soluble and insoluble fractions rather than a simple disappearance. Seed structure changes as hydration prepares it for cooking.
What we often want to reduce: phytates and oligosaccharides
Soaking can reduce phytates, tannins, enzyme inhibitors and oligosaccharides to different degrees. A 2026 scientific review of pulse processing notes that the magnitude depends strongly on species and conditions and that leaching into water is one mechanism.
Raffinose-family oligosaccharides are particularly relevant because gut bacteria can ferment them and contribute to gas in some people. Soaking can lower part of this load, although it does not eliminate fermentation associated with pulse fibre.
Can soaking improve mineral availability?
Even if a small amount of mineral is lost, reducing phytate can improve availability. This shows why total content and potential absorption are not identical concepts.
For iron specifically, see our guide on improving iron absorption from pulses.
Should soaking water be reused?
There is no universal answer. For chickpeas and many beans it is common to discard the water and cook in fresh water, removing compounds that have migrated out. Reusing it may recover soluble compounds but can also reintroduce oligosaccharides and other substances you were trying to reduce.
The decision depends on the pulse, recipe and individual tolerance. Soaking water never replaces adequate cooking.
How long should pulses be soaked?
The ideal time depends on the pulse. Chickpeas and many beans often benefit from an overnight soak, while small lentils can often be cooked without soaking. Extending soaking far beyond what is needed does not automatically add benefits and, in warm conditions, can encourage unwanted fermentation.
For long soaking periods or warm weather, refrigeration is a sensible precaution.
What about bicarbonate?
An alkaline soaking medium can speed softening and enhance the reduction of some antinutritional factors, but it can also alter texture more strongly and increase losses of certain compounds. Bicarbonate is not necessary for every pulse or recipe.
Bottom line
Yes, soaking can carry away small amounts of minerals, water-soluble vitamins and bioactive compounds. It also shortens cooking and reduces some phytates, tannins and oligosaccharides. For chickpeas and beans, sensible soaking remains a useful culinary technique; there is no reason to avoid it for fear of 'losing all the nutrients'.
Explore more in our legume guides and our article on what happens to nutrients during cooking.
Frequently asked questions
Does soaking water contain nutrients?
Yes. It can contain minerals, sugars, phenolic compounds and other soluble substances that have moved out of the pulse.
Must soaking water always be discarded?
For chickpeas and many beans it is common and useful to discard it, but the choice also depends on the recipe and digestive tolerance.
Does soaking remove protein?
No. Most protein remains in the seed; only small amounts of soluble nitrogen compounds may move into the water.
Is a longer soak always better?
No. Once the pulse is hydrated, unnecessarily long soaking can increase soluble losses and, in warm conditions, encourage fermentation.
Sources and editorial approach
This guide prioritises scientific reviews on pulse processing and institutional nutrition sources. Key references include a recent review of how soaking, cooking and other processes change legumes, a review of antinutrients and traditional preparation methods, and, for iron, the NIH Office of Dietary Supplements. Exact nutrient values vary with variety, origin, storage, hydration and cooking method, so we avoid treating a single number as universal.
