How Much Does Soaking Almonds Reduce Oxalates?

Almonds are a nutritious food, but also high in oxalates, natural compounds that can contribute to kidney stone formation in susceptible individuals. Soaking almonds is a common practice believed to reduce these antinutrients, but the actual percentage of reduction is often debated.

Quick Summary

Soaking almonds can moderately reduce their soluble oxalate content by leaching the compounds into the water, with the effectiveness varying based on time and other factors. The process also improves digestion and softens the texture, but does not eliminate all oxalates.

Key Points

• Moderate Reduction: Soaking almonds can lead to a moderate reduction in soluble oxalates, which are the most easily absorbed by the body.

• Soluble vs. Insoluble Oxalates: Soaking primarily affects the soluble oxalates, but a portion of insoluble oxalates remains.

• Skin Removal is Key: Since almond skin contains a high concentration of oxalates, blanching and removing the skin can significantly reduce overall oxalate content.

• Soaking Benefits Beyond Oxalates: The soaking process also improves digestibility, softens the texture, and can reduce other antinutrients like tannins.

• Complementary Strategies: For a low-oxalate diet, pairing soaked almonds with calcium-rich foods is a key strategy to further reduce oxalate absorption.

• Varying Effectiveness: The exact percentage of oxalate reduction is not a fixed number and depends on the duration of soaking and whether the skin is removed.

Understanding Oxalates in Almonds

Oxalates, or oxalic acid, are naturally occurring compounds found in many plant foods, including nuts, grains, and vegetables. For most healthy individuals, consuming oxalates is not an issue. The body can process and excrete them without any adverse effects. However, for people prone to kidney stones, particularly calcium oxalate stones, controlling dietary oxalate intake is often recommended. Almonds are notably high in oxalates, with a significant concentration in their brown outer skin. This has led to the popularity of preparation methods like soaking to minimize potential negative effects.

Why Soaking is Believed to Reduce Oxalates

Soaking works on the principle of water-solubility. Soluble oxalates, which constitute a significant portion of the total oxalates in almonds, can leach out into the soaking water over time. By discarding this water, you can effectively remove a portion of these compounds. This is a culinary technique long used to reduce antinutrients in legumes, grains, and some nuts, though its specific effectiveness on almonds varies. The process also helps to soften the almond and make it more palatable and easier to digest.

The Data on Soaking and Oxalate Reduction

Research on the exact percentage of oxalate reduction from soaking almonds is surprisingly limited and often focuses on phytic acid instead. However, studies on legumes and general nut-soaking practices provide some valuable insights. One study on various pulses (including some beans and chickpeas, but not specifically almonds) indicated that soaking can reduce total oxalates by a notable percentage, from roughly 17% to 52% depending on the legume type. While not a direct measure for almonds, it supports the principle that the process can be effective. Other sources, drawing on similar logic, suggest that soaking can lead to a significant reduction in soluble oxalates in almonds as well. It is crucial to remember that soaking reduces soluble oxalates, which are the most bioavailable, but does not eliminate all oxalates, as some are insoluble.

Factors Influencing Oxalate Reduction

The extent of oxalate reduction depends on several key variables:

• Soaking Time: A longer soak generally yields a greater reduction. Overnight soaking (8-12 hours) is a common recommendation, though some sources suggest up to 24 hours.
• Water Temperature: Using warm water might accelerate the leaching process, but room-temperature or cold water is standard for overnight soaking to prevent spoilage.
• Adding an Acidic Medium: Some advocates recommend adding a splash of lemon juice or another acidic component to the soaking water. The theory is that this further aids in breaking down antinutrients, though concrete evidence specifically for almond oxalates is mixed.
• Discarding the Soaking Water: This step is critical. The leached oxalates are in the water, so it must be thrown out and the almonds thoroughly rinsed afterward.
• Skin Removal: Since a significant portion of oxalates resides in the almond's skin, blanching and removing the skin is an effective way to lower the total oxalate content. Some believe soaking makes the skin easier to peel, combining both strategies.

Soaking vs. Other Preparation Methods

To put soaking into context, it helps to compare it with other methods of preparing almonds, as different approaches affect nutrient and antinutrient levels differently.

Preparation Method	Effect on Oxalates	Other Notable Effects	Best For...
Soaking (Overnight)	Moderately reduces soluble oxalates.	Improves digestibility, softens texture, removes some tannins.	Improving digestion and reducing oxalate load without significant heat processing.
Blanching	Does not directly reduce oxalates within the kernel, but removes the high-oxalate skin.	Makes almonds easier to peel, removes some tannins.	Individuals who want to remove the bulk of the oxalates concentrated in the skin.
Roasting	Minimal effect on oxalates, though can reduce other antinutrients like phytates.	Changes flavor profile, increases crunchiness.	Flavor preference rather than oxalate reduction.
Sprouting	Can reduce both oxalates and phytic acid, similar to soaking but with more activation of enzymes.	Increases nutrient availability, changes texture.	Maximum antinutrient reduction, though less common for almonds.
Adding Calcium (during meal)	Oxalates bind to calcium in the gut, reducing absorption.	Minimal effect on the almonds themselves.	Reducing oxalate absorption from any high-oxalate food, including almonds, during a meal.

A Step-by-Step Guide to Soaking Almonds

For those interested in reducing almond oxalates, here is a simple process:

1. Place your desired amount of raw almonds in a bowl.
2. Cover the almonds with filtered water. The water level should be about an inch above the almonds.
3. Optionally, add a pinch of salt or a small amount of lemon juice to the water. Some believe this enhances the effect, though research is mixed on the benefit for almonds.
4. Cover the bowl and let the almonds soak overnight, or for at least 8-12 hours.
5. The next morning, the almonds will appear plump and the soaking water will be murky. This indicates that some compounds have leached into the water.
6. Drain the soaking water completely. Be sure to discard it.
7. Rinse the almonds thoroughly under running water.
8. The almonds are now ready to be eaten. For a crunchier texture, they can be dehydrated in a food dehydrator or low-temperature oven.

Conclusion: The Final Verdict

While definitive, universal figures on exactly how much does soaking almonds reduce oxalates are elusive, based on the principles of water-solubility and extrapolation from similar studies, it is clear that soaking is an effective method for reducing soluble oxalate content. The exact percentage of reduction will vary based on several factors, but it can be a significant step for those on a low-oxalate diet. Pairing soaking with other strategies like peeling the skin and consuming calcium-rich foods alongside almonds can further minimize oxalate absorption. For the majority of people, however, soaking is simply a way to improve digestibility and texture, making almonds a more pleasant and beneficial snack. The process is a simple, low-effort technique that can contribute positively to overall health and dietary management.

Here is an authoritative outbound link to a National Institutes of Health article on diet-induced oxalate issues.

Frequently Asked Questions

Does soaking almonds overnight really reduce oxalates?

Yes, soaking almonds overnight can moderately reduce their soluble oxalate content. This is because oxalates are water-soluble and can leach out into the soaking water. Discarding the murky soaking water and rinsing the almonds removes these leached compounds.

How long should I soak almonds to reduce oxalates?

For effective oxalate reduction, it is best to soak almonds for at least 8 to 12 hours, typically overnight. Some people extend this to 24 hours, but for most purposes, overnight is sufficient.

Is blanching or soaking better for reducing oxalates in almonds?

Combining both methods is most effective. Blanching removes the high-oxalate skin, which is a major source of the compound. Soaking then reduces the remaining soluble oxalates within the kernel itself. For maximum reduction, remove the skin after soaking.

Does roasting almonds reduce their oxalate content?

Roasting has a minimal effect on the oxalate content of almonds. While it does reduce other antinutrients like phytates, soaking is a more effective method for targeted oxalate reduction.

What is the best method to reduce oxalates from almonds for someone with kidney stones?

For individuals with kidney stones, the most effective strategy is a combination approach. Soak the almonds overnight, blanch and peel off the skin, and consume them with calcium-rich foods to help bind any remaining oxalates in the gut.

Can I use almond flour from soaked almonds?

Yes, you can make almond flour from soaked and then dehydrated almonds. After soaking and peeling, the almonds need to be thoroughly dried, either in a low-temperature oven or a food dehydrator, before being ground into flour. This creates a lower-oxalate flour option.

Does adding lemon juice to the soaking water help reduce oxalates?

While anecdotal evidence suggests that adding an acidic medium like lemon juice might aid in breaking down antinutrients, research on its specific effect on almond oxalate reduction is limited. It does not hurt and may provide a marginal benefit.