What You Need to Know About Boiling, Soaking, and Preparing High-Oxalate Foods

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If you’ve recently been diagnosed with hyperoxaluria or have been told to follow a low-oxalate diet, you may be wondering if you need to give up some of your favorite foods.

The good news is…not necessarily.

For many foods, how you prepare them can make a meaningful difference. Simple cooking techniques, such as boiling and draining vegetables, can reduce the amount of dietary oxalate they contain. While these methods don’t remove oxalate completely, they may help lower the amount your body absorbs.

Whether these strategies are appropriate for you depends on your individual condition and the recommendations of your healthcare team.

What Is Oxalate?

Oxalate is a naturally occurring substance found in many plant foods, including leafy greens, nuts, beans, potatoes, and chocolate.

For many people, oxalate isn’t a problem. But for people with enteric hyperoxaluria (EH) or those who develop calcium oxalate kidney stones, reducing dietary oxalate may be part of an overall treatment plan.

If you have Primary Hyperoxaluria (PH), your body produces excess oxalate regardless of what you eat. While your healthcare team may still recommend dietary changes, medications, hydration, and ongoing medical care remain the foundation of treatment.

The Short Answer

Yes.

Boiling certain high-oxalate foods—and discarding the cooking water—can significantly reduce the amount of soluble oxalate they contain.

Why?

Because oxalate is water-soluble. During cooking, some of it moves from the food into the boiling water. When you pour that water away, you’re also removing some of the oxalate.

The amount removed varies depending on the food and how it’s prepared, but research has shown that boiling can substantially reduce soluble oxalate in many vegetables.

Six Simple Ways to Reduce Dietary Oxalate

You don’t need special equipment or complicated recipes. Small changes in how you prepare food can make a difference.

1. Follow Your Healthcare Team’s Advice

Not everyone needs the same level of oxalate restriction. Your treatment plan should always come first.

2. Boil High-Oxalate Vegetables

Boiling is generally more effective than roasting, baking, or frying for reducing soluble oxalate.

3. Always Discard the Cooking Water

This is one of the most important steps. Much of the oxalate that leaves the food ends up in the water.

4. Soak Foods Before Cooking

For some vegetables and dried beans, soaking before cooking may help reduce oxalate even further.

5. Peel Root Vegetables When Appropriate

Some oxalate is concentrated near or in the skin of certain vegetables.

6. Include Calcium-Rich Foods with Meals

If recommended by your healthcare team, calcium-rich foods eaten with meals can help bind some dietary oxalate in the digestive tract before it is absorbed.

Foods That Benefit Most from Boiling

Some vegetables respond particularly well to boiling and draining.

Remember that cooking reduces oxalate—it doesn’t eliminate it completely.

What About Smoothies?

Raw spinach smoothies have become popular because they’re easy and nutritious.

However, spinach is naturally one of the highest-oxalate vegetables.

If you’re following a low-oxalate eating plan, consider asking your healthcare team whether lower-oxalate greens may be a better choice or whether cooked spinach in moderate portions is appropriate for you.

Pair Cooking with Calcium

Cooking is only one part of the picture.

Research suggests that eating calcium-containing foods with meals can help bind dietary oxalate in the digestive tract, reducing the amount available for absorption.

Examples include:

• Yogurt with oatmeal
• Cheese on a baked potato
• Milk with meals
• Other calcium-rich foods recommended by your healthcare team

What Cooking Can’t Do

Cooking is helpful—but it’s not a 100% fix.

Keep these points in mind:

• Some foods remain relatively high in oxalate even after boiling.
• Freezing does not reduce oxalate.
• Roasting and frying remove very little oxalate.
• People with Primary Hyperoxaluria still produce oxalate within their bodies regardless of diet.

Frequently Asked Questions

Can I still eat spinach?

Possibly. Boiling and draining spinach reduces its soluble oxalate content, but it remains higher in oxalate than many other vegetables. Ask your healthcare team what amount is appropriate for you.

Can I use the cooking water in soup?

It’s generally best to avoid using cooking water from high-oxalate vegetables because some of the oxalate has moved into the liquid.

Does steaming work?

Steaming may reduce some oxalate, but boiling and draining is generally more effective.

Does freezing vegetables reduce oxalate?

No. Freezing does not significantly change oxalate content.

Key Takeaways

Learn More

Looking for more information? Explore additional OHF resources on:

• Understanding Hyperoxaluria
• Primary Hyperoxaluria (PH)
• Enteric Hyperoxaluria (EH)
• Low-Oxalate Diet
• Calcium & Oxalate
• Hydration and Kidney Health
• Finding Expert Hyperoxaluria Care

Medical Disclaimer