Soaking walnuts does not remove significant amounts of their core nutrients, but it doesn’t meaningfully boost nutrient absorption either. A study published in the journal Nutrients found that soaking nuts resulted in slightly lower mineral concentrations overall and did not improve the ratio of phytate (an antinutrient) to minerals. The differences in phytate levels between soaked and unsoaked nuts were small, ranging from a 12% decrease to a 10% increase. In short, the nutritional profile stays largely the same, with minor losses rather than gains.
What Soaking Actually Does to Walnut Nutrition
The idea behind soaking walnuts is that water breaks down phytic acid, a compound in nuts that can bind to minerals like zinc, iron, and calcium and reduce how well your body absorbs them. In grains and legumes, soaking does reduce phytic acid meaningfully. But walnuts and other tree nuts behave differently. Their phytate levels barely budge with soaking, and because some minerals leach into the soaking water, you can actually end up with slightly fewer minerals than you started with. This is especially true if the walnuts are chopped before soaking, which increases the surface area exposed to water.
The bottom line from the most rigorous research available: the popular concept of “activating” nuts through soaking does not result in greater nutrient bioavailability. You’re not unlocking hidden nutrition, and you’re not losing much either. The walnut you eat after soaking is nutritionally very similar to the one you’d eat straight from the bag.
Where Soaking Does Make a Difference
While the mineral and vitamin content stays roughly the same, soaking does change walnuts in ways that matter for some people. The most notable effect is on digestibility. Research from a study on walnut proteins found that soaking, and especially peeling the skin afterward, significantly improved the in vitro digestibility of walnut proteins. The soaking process activates natural enzymes (proteases) already present in the walnut that help break down proteins, making them easier for your gut to handle.
If you’ve ever felt bloated or heavy after eating a handful of raw walnuts, this is relevant. The improved digestibility doesn’t mean more nutrients are created. It means your body may have an easier time accessing the protein that’s already there.
Tannins, Bitterness, and Flavor
The most noticeable change from soaking walnuts isn’t nutritional at all. It’s about taste. Walnuts contain tannins, the same astringent compounds found in red wine and tea, concentrated mostly in the papery brown skin. Soaking draws tannins out into the water, which is why the soaking liquid turns dark brown. Changing the water a few times during soaking pulls out even more tannins, and each batch of water comes out progressively lighter.
The result is a walnut that tastes noticeably less bitter and more buttery. The color lightens too, shifting from deep brown to a paler tan. For people who find raw walnuts unpleasantly astringent, soaking transforms the eating experience. Tannins are not harmful, but they can interfere slightly with iron absorption and they contribute that dry, puckering mouthfeel some people dislike. Removing them is a flavor preference, not a nutritional necessity.
Food Safety During Soaking
One risk that often goes unmentioned in soaking guides is bacterial growth. Research from Purdue University found that soaking tree nuts, including walnuts, at room temperature creates conditions where harmful bacteria can multiply if pathogens are present on the nut surface. This is particularly concerning when soaked nuts are used to make homemade nut milks or fermented products like cashew cheese, where the bacteria have even more time to grow.
The fix is simple: soak your walnuts in the refrigerator instead of on the counter. Use clean utensils, wash your hands before handling, and don’t let nuts sit in water at room temperature for extended periods. Most soaking guides recommend 7 to 8 hours (overnight works well), and refrigeration keeps things safe without affecting the soaking process.
How to Soak Walnuts If You Choose To
Place about 4 cups of raw walnuts in a bowl and cover them with filtered water. Adding a teaspoon of salt to the water is a common practice that may help draw out tannins more effectively. Let them soak in the refrigerator for at least 7 hours or overnight. If you want to reduce bitterness further, drain and replace the water once or twice during the soak.
After soaking, walnuts will be soft and waterlogged. You can eat them this way, but most people prefer to dry them. A dehydrator set to 150°F or below preserves the nut’s natural enzymes. An oven on its lowest setting with the door slightly cracked works too, though it takes several hours. Once fully dried, soaked walnuts will have a lighter crunch than raw ones and a milder, sweeter flavor. Store them in the refrigerator or freezer, since the reduced tannin content means they have slightly less natural protection against going rancid.
Who Benefits Most From Soaking
If your main concern is nutrition, soaking walnuts is unnecessary. The mineral content stays about the same or drops slightly, and phytic acid levels don’t change enough to matter. You’re better off simply eating walnuts regularly, soaked or not, to get their well-documented benefits for heart health and brain function.
Soaking makes the most sense if you find raw walnuts too bitter, if you experience digestive discomfort after eating them, or if you’re using them in recipes like smoothies or nut milks where a milder flavor and softer texture are desirable. It’s a culinary technique more than a nutritional one. The nutrients stay put either way.