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Are Oxalate Foods Bad for You?

spinach is high in oxalate

Some of the healthiest foods have oxalate. Eating oxalate foods in moderation is not bad for you. Oxalate can be 'bad' for people who are sensitive to them. For most people who eat a well-balanced diet and drink enough water, oxalate is not something to be overly concerned about.

Bioavailability of Oxalates

Bioavailability is how much of something you eat gets absorbed by your body and used for its needs. Not all foods with oxalates affect our bodies the same way. It depends on the food. Our bodies absorb some oxalates more than others. For example, spinach is more likely to absorb oxalates than nuts.

Bioavailability matters because the more oxalates our bodies absorb. Oxalate absorption raises the risk of issues for some. But don't worry too much! You can eat smarter to lower the risk. Mixing foods high in oxalates with calcium-rich foods can help. Calcium can capture oxalates and prevent their absorption.

Why Are People Concerned About Oxalate?

Oxalate can form crystals in the body when they bind with calcium. These crystals can contribute to the formation of kidney stones or be associated with other health issues.

Here are some key points to consider about oxalate:

Kidney Stones: Oxalate can contribute to the formation of kidney stones, particularly in individuals prone to stone formation. Kidney stones can be painful and may require medical treatment.

Individual Sensitivity: Some people are more sensitive to oxalates than others. If you have a history of kidney stones or other oxalate-related health issues, your healthcare provider may recommend limiting high-oxalate foods.

Balanced Diet: Many foods that contain oxalates are also rich in essential nutrients and antioxidants. For example, leafy greens like spinach and Swiss chard are high in oxalates but provide vitamins, minerals, and fibre necessary for overall health.

Cooking and Preparation: Cooking, boiling, or blanching certain high-oxalate foods can help reduce their oxalate content, making them less likely to contribute to crystal formation in the body.

Hydration: Staying well-hydrated can help dilute the concentration of oxalates in the urine, potentially reducing the risk of stone formation.

Personalised Approach: It's essential to consult with a healthcare provider or registered dietitian if you have concerns about oxalates in your diet. They can provide personalised guidance based on your health history and dietary preferences.

For more on oxalate read the oxalate section in Lifestyle Resources and click the article: Is There Such a Thing as “Anti-Nutrients”? A Narrative Review of Perceived Problematic Plant Compounds by Weston Petroski and Deanna M. Minich, 2020.

Understanding Oxalate Levels in Leafy Greens

Leafy greens like spinach and kale are known for their high oxalate levels. While they provide many essential nutrients, their oxalate content can pose a risk for certain individuals. Those who are prone to calcium oxalate kidney stones may need to monitor their oxalate intake. This can help to prevent the formation of these common types of kidney stones.

The Role of Calcium-Rich Foods in an Oxalate Diet

The absorption of oxalates can be influenced by the amount of dietary calcium consumed. Calcium binds to oxalates in the intestines, reducing their absorption. Lowering the risk of calcium oxalate kidney stones. Incorporating Calcium-rich foods into your diet can help reduce the risk of calcium oxalate stones.

This is particularly important for those with a history of kidney stones or inflammatory bowel disease. Ensuring adequate plant-based calcium intake can be a crucial part of a low-oxalate diet. Adequate calcium absorption from foods can help maintain healthy calcium levels. It can also support digestive health.

Hydration and Kidney Stone Prevention

Drinking plenty of water is essential for reducing the risk of kidney stones. High fluid intake dilutes the urine. This decreases the concentration of oxalates and other substances that can lead to stone formation. For those at risk, maintaining a high urine volume is an effective way to prevent the buildup of oxalates and other compounds in the urinary tract.

Managing Oxalate Intake with Dietary Choices

People looking to manage their oxalate consumption should focus on low-oxalate foods. They should watch their portions of oxalate-rich foods. Substituting high-oxalate foods with low-oxalate alternatives can help reduce oxalate levels.

Health Benefits and Risks of Oxalate-Containing Foods

Oxalate-containing foods like dark chocolate and green smoothies offer various health benefits. But they also create risks for people with certain health conditions. Consuming these foods in moderation is important. Balancing them with low-oxalate nutrient-dense foods can reduce the adverse effects of high oxalate intake. It’s essential to maintain a healthy diet that supports digestive health and bone health.

How Oxalate Levels Are Classified

  • Very Low: Less than 1 mg per 100g

  • Low: 1 - 5 mg per 100g

  • Moderate: 5 - 10 mg per 100g

  • High: More than 10 mg per 100g

Very High Oxalate Vegetables Table

Here's a table of some of the highest common oxalate vegetables and their approximate oxalate content per 100 grams base on the OHF database:


Average Ox (mg) per 100 g

Serving Size

Serving Size (g)

Calc Oxalate per serving

Swiss Chard, Red, raw


1 cup



Mangold, Silverbeet or Spinach beet


1/2 cup



Sorrel, raw


1 cup, chopped



Swiss Chard, Red or green, boiled and steamed


1/2 cup, chopped



Swiss Chard, Green, raw


1 cup



Spinach, fresh or frozen, boiled or steamed


1/2 cup



Low Oxalate Swaps

Here are some lower swaps:

High Oxalate Foods

Lower Oxalate Swap


Romaine lettuce or iceberg lettuce


​Apples or pears

Swiss Chard (cooked)

Kale 3

Beets (cooked)


​Sweet Potatoes

​White potatoes

In Summary, Are Oxalate Foods Bad for You?

Are oxalate foods bad for you? Oxalate foods are not bad for everyone but can be problematic for some people. Oxalate itself is naturally occurring in some foods and is not inherently bad.

Read Kidney Stones: Foods That Cause Them for more on kidney stones.


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