Can you cook oxalates out of food?

December 25, 2025 •

4 min read

Research indicates that boiling high-oxalate vegetables like spinach can significantly reduce their soluble oxalate content, with reductions often exceeding 60%. This confirms that you can, to some extent, cook oxalates out of food, but the success depends on the technique used and the type of oxalate.

Quick Summary

Boiling and soaking effectively reduce water-soluble oxalates by leaching them into water, but other methods like roasting are largely ineffective at lowering levels.

Key Points

Boiling is Most Effective: Boiling high-oxalate foods like spinach and chard can significantly reduce their soluble oxalate content by leaching it into the water.
Discard the Water: To successfully remove oxalates, the cooking or soaking water must be discarded, as the oxalates will have leached into it.
Steaming is Less Effective: Steaming can reduce some soluble oxalates, but it is less efficient than boiling because there is less direct water contact.
Roasting Does Not Reduce Oxalates: Cooking methods that do not involve water, such as roasting or sautéing, are ineffective at removing oxalates.
Calcium Pairing is Crucial: Consuming calcium-rich foods alongside high-oxalate foods helps bind oxalates in the digestive tract, preventing their absorption.
Not All Oxalates are Created Equal: Cooking primarily reduces soluble oxalates; insoluble oxalates, like calcium oxalate, are far less affected.
High-Oxalate Foods Exist in Many Categories: Be mindful of oxalates in certain vegetables, nuts, grains, and even cocoa powder.

Understanding Oxalates: Soluble vs. Insoluble

Oxalates, or oxalic acid, are naturally occurring compounds found in many plant foods. They are considered "antinutrients" because they can bind with minerals like calcium, magnesium, and iron, inhibiting their absorption. The oxalates in food exist in two forms: water-soluble and water-insoluble. The distinction between these two forms is critical for understanding how cooking affects their content.

Soluble oxalates can dissolve in water, making them susceptible to removal through boiling or soaking. Insoluble oxalates, primarily calcium oxalate crystals, are much less affected by water-based cooking methods. While the total oxalate content of a food is important, it's the soluble fraction that is most influenced by proper cooking techniques. This is particularly relevant for individuals prone to kidney stones, as calcium oxalate is the most common type of kidney stone.

The Most Effective Cooking Methods for Oxalate Reduction

To achieve the greatest reduction in oxalates, water-based cooking methods are essential. The key principle is leaching, where soluble oxalates move out of the food and into the cooking water.

Boiling and Blanching: This is the most effective method for reducing soluble oxalate levels. Studies have shown that boiling can remove a substantial portion of oxalates, with some studies reporting reductions of 30-87% depending on the vegetable. For high-oxalate foods like spinach or chard, a quick blanch (boiling for a few minutes) followed by rinsing with cold water is highly effective. Crucially, the cooking water, which now contains the leached oxalates, must be discarded. Cooking these vegetables in soup, for example, would only redistribute the oxalates into the broth, which would then be consumed.
Steaming: Steaming is a moderately effective method for reducing oxalates. While not as potent as boiling due to less direct contact with the water, some soluble oxalates can still be leached out. This method is a good compromise for those who want to reduce oxalates while preserving more of the food's other nutrients.
Soaking: Soaking is particularly useful for reducing oxalates in legumes and grains. Soaking beans or lentils overnight and then discarding the water can help leach out some of the soluble oxalates before cooking begins. For nuts and seeds, soaking and rinsing can also be beneficial.

Ineffective Cooking Methods for Oxalate Removal

Not all cooking methods are created equal when it comes to oxalates. Heat alone does not destroy oxalates, and without a water medium for leaching, they remain in the food.

Roasting and Sautéing: These dry-heat methods do not remove oxalates. Since there is no water for the soluble oxalates to leach into, the levels within the food remain largely unchanged. For foods like sweet potatoes, which are high in oxalates, roasting will not provide any reduction.
Baking: Similar to roasting, baking in a dry oven will not reduce oxalate content. For a food like baked taro, some moisture loss may even concentrate the remaining oxalates.

Practical Tips for a Lower-Oxalate Diet

For individuals advised to follow a low-oxalate diet, integrating these cooking techniques can be highly beneficial. Here is a list of high-oxalate foods that benefit most from proper preparation:

Spinach
Rhubarb
Beet greens and beets
Swiss chard
Almonds and other nuts
Legumes and soy products
Cocoa powder and dark chocolate
Wheat bran

The Role of Calcium in Oxalate Absorption Another powerful strategy for managing oxalate intake is pairing high-oxalate foods with calcium-rich foods. When consumed together, the calcium binds with the oxalate in the digestive tract. This forms calcium oxalate, which is then excreted in the stool, preventing it from being absorbed into the body. Excellent calcium sources include dairy products, calcium-set tofu, and fortified plant milks. This approach may be more effective for some individuals than strictly limiting high-oxalate foods.

Comparison of Cooking Methods for Oxalate Reduction


Cooking Method	Mechanism	Soluble Oxalate Reduction	Insoluble Oxalate Reduction	Key Practice
Boiling / Blanching	Leaching into water	High (30-87%)	Low / Variable	Discard cooking water
Steaming	Limited leaching into water	Moderate (5-53%)	Variable	Use less water / limit contact
Soaking	Leaching into water	Good (for grains/legumes)	Variable	Discard soaking water
Roasting / Sautéing	No water for leaching	None	None	Ineffective for reduction
Baking	No water for leaching	None	None	Ineffective for reduction

Conclusion: Making Informed Dietary Choices

Yes, you can cook oxalates out of food, but the effectiveness is highly dependent on the cooking method used. Boiling and blanching, where the soluble oxalates are leached into water and then discarded, are the most reliable methods for significant reduction. For those at risk of kidney stones, incorporating these cooking strategies, in combination with drinking sufficient fluids and consuming calcium-rich foods alongside high-oxalate items, offers the most comprehensive approach to managing oxalate levels. However, as oxalates are a complex topic and individual needs vary, it is always best to consult a healthcare professional for personalized dietary advice.

For more detailed information on managing oxalate intake, consider consulting resources from the National Kidney Foundation.

Frequently Asked Questions

High-oxalate foods include spinach, rhubarb, beets, Swiss chard, almonds, and cocoa powder. Some legumes and grains like wheat bran also contain significant amounts.

No, a low-oxalate diet is not necessary for most people. It is primarily recommended for individuals prone to forming calcium oxalate kidney stones or those with certain medical conditions.

Calcium binds to oxalates in the intestines before they can be absorbed by the body. This helps excrete them through the digestive system, reducing the amount that reaches the kidneys.

Using a pressure cooker or slow cooker with plenty of water can help reduce oxalates through leaching, similar to boiling. However, the cooking liquid must still be discarded to remove the leached oxalates.

Juicing does not effectively remove oxalates. In many cases, it may even concentrate them, especially in juices made from high-oxalate vegetables like spinach. It is better to boil or blanch these vegetables and discard the water.

The best way to cook spinach to reduce oxalates is to blanch it. Boil the spinach for 1-3 minutes in plenty of water, then drain and rinse it thoroughly. Discard the boiling water.

While generally safe, an extremely low-oxalate diet can restrict many nutrient-dense foods. Rapidly reducing oxalate intake can also cause 'oxalate dumping' symptoms in some individuals. It is best to consult a professional before making drastic dietary changes.

Most oxalate is excreted through stool, especially when paired with calcium. The kidneys filter excess oxalate from the bloodstream, which is then excreted in urine. High levels in the kidneys can lead to crystal and stone formation.