How do you remove oxalates from chard?

November 29, 2025 •

4 min read

Oxalates are naturally occurring compounds found in many plant-based foods, including chard. For those concerned about kidney stones or mineral absorption, understanding how to reduce these compounds is important. So, how do you remove oxalates from chard effectively?

Quick Summary

Several cooking methods can significantly lower oxalate levels in chard. Boiling and blanching are the most effective techniques, while steaming offers a moderate reduction. Pairing with calcium-rich foods can further limit absorption and help your body manage oxalates.

Key Points

Boiling is Key: As oxalates are water-soluble, boiling chard in a large volume of water and discarding the liquid is the most effective method for removal.
Pair with Calcium: Eating calcium-rich foods with chard helps bind oxalates in the digestive tract, preventing their absorption into the body.
Steaming is a Compromise: Steaming reduces oxalate content to a lesser degree than boiling but better preserves other water-soluble nutrients.
Combine Methods: For maximum oxalate reduction, blanch chard before adding it to other dishes or recipes.
Avoid Raw for High Sensitivity: Individuals with a high risk of kidney stones should avoid consuming large quantities of raw chard, as oxalates are highly concentrated when uncooked.
Stems First: Since chard stems are denser and take longer to cook, they should be added to boiling water a few minutes before the leaves.

What Are Oxalates and Why Should You Consider Removing Them?

Oxalates, or oxalic acid, are natural compounds found in many plants, acting as a defense mechanism against insects. While harmless for most people in moderation, high concentrations can pose health risks for sensitive individuals, particularly those prone to kidney stones. Oxalates bind with minerals like calcium in the body, which can interfere with nutrient absorption and form calcium oxalate crystals. These crystals are the primary component of most kidney stones. Reducing oxalate content in high-oxalate foods like chard can be a key part of a kidney-stone-prevention diet.

The Most Effective Method: Boiling

Boiling is widely considered the most effective cooking method for reducing oxalates in vegetables like chard. Because oxalates are water-soluble, they leach out into the cooking water during boiling. A study published in the Journal of Agricultural and Food Chemistry showed that boiling significantly reduced soluble oxalate content in vegetables like Swiss chard. It is crucial to discard the boiling water and not use it in soups or sauces, as this would reintroduce the leached oxalates back into your meal.

How to Boil Chard for Maximum Oxalate Removal:

Wash the chard thoroughly under cold water.
Chop the chard leaves and stems into smaller, manageable pieces to increase surface area.
Bring a large pot of water to a rolling boil.
Add the chopped chard and boil for at least 5 to 10 minutes. The stems may require slightly more cooking time than the leaves.
Drain the chard using a colander and discard the cooking water completely.
Rinse the chard with fresh water after boiling to remove any residual oxalates.

A Moderate Alternative: Steaming

Steaming is another viable method for reducing oxalates, though it is less effective than boiling. Steaming exposes the chard to hot vapor, which draws some of the soluble oxalates out. It is a good compromise if you are also concerned with preserving water-soluble vitamins, as it results in less nutrient loss compared to boiling.

How to Steam Chard to Reduce Oxalates:

Wash and chop the chard leaves and stems.
Fill a pot with a small amount of water (1-2 inches) and place a steamer basket inside, ensuring the water does not touch the basket.
Bring the water to a boil, then add the chard stems first, followed by the leaves after a few minutes.
Steam for about 5 to 7 minutes, or until tender.
Discard the water in the pot. The steamed chard can then be used in your recipe.

Mitigating Oxalate Absorption with Calcium

One of the most effective strategies is to pair cooked chard with a calcium-rich food source. When calcium is consumed alongside high-oxalate foods, it binds with the oxalates in the stomach and intestines before they can be absorbed by the body. The resulting calcium oxalate compound is then safely excreted from the body.

Foods to pair with chard:

Dairy: Top your cooked chard with grated parmesan cheese or crumble feta cheese into the dish. Yogurt and milk are also good options. For example, a side of yogurt can be served with a chard dish.
Other sources: Nutritional yeast, calcium-fortified plant-based milks, or calcium-set tofu can be excellent plant-based pairings.

Comparison of Oxalate-Reducing Cooking Methods


Method	Effectiveness	Nutrient Retention	Effort	Best For
Boiling	Highest Reduction	Lowest	Medium	Maximum oxalate removal
Blanching	Very High Reduction	Moderate	High	A quick pre-cooking step
Steaming	Moderate Reduction	High	Medium	Balancing oxalate removal and nutrient retention
Sautéing/Roasting	Minimal to None	High	Low	When oxalates are not a concern

Best Practices for Cooking Chard with Reduced Oxalates

For those with high oxalate sensitivity, the best approach is to combine preparation techniques. Start by blanching the chard in a large pot of boiling water for a couple of minutes, then plunge it into ice water to stop the cooking process. Discard the blanching water. You can then proceed to use this blanched chard in your recipe, whether sautéing or baking, and remember to pair it with a calcium-rich ingredient to further reduce bioavailability. This multi-step process offers the greatest reduction in oxalate content. However, for most people, a simple boiling or steaming and discarding the water is sufficient to enjoy chard's nutritional benefits without worry.

Conclusion

While Swiss chard is a nutritious leafy green, its high oxalate content can be a concern for some. The most effective way to reduce oxalates from chard is through wet-cooking methods like boiling or blanching, followed by discarding the cooking water. Combining these techniques with pairing chard with a calcium-rich food source provides a comprehensive strategy for minimizing oxalate absorption. By adopting these cooking techniques, you can safely enjoy the vitamins, minerals, and phytonutrients that chard has to offer while mitigating potential health risks associated with oxalates.

For more research-backed information on oxalates and kidney stone prevention, consult trusted health resources such as the National Kidney Foundation.

Frequently Asked Questions

Boiling is the most effective cooking method for reducing oxalates, significantly lowering the soluble oxalate content. However, it does not remove all oxalates, and some insoluble oxalates will remain.

Boiling is more effective at removing oxalates from chard than steaming, as the oxalates leach into the larger volume of water. Steaming retains more water-soluble vitamins, but boiling is superior for oxalate reduction.

If you are sensitive to oxalates or have a history of kidney stones, it is not recommended to eat large quantities of raw chard. Cooking significantly reduces the oxalate content, making it safer for consumption.

Pair chard with calcium-rich foods like cheese, yogurt, milk, or calcium-set tofu. The calcium binds to the oxalates during digestion, preventing their absorption.

While soaking is recommended for some legumes, boiling is the primary and most effective method for removing oxalates from chard. You can also blanch chard, which is a rapid, short-term boiling process.

You should always discard the water used for boiling or blanching chard. This water contains the oxalates that have leached out of the vegetable, and consuming it would defeat the purpose of the cooking process.

Yes, it is best to separate and cook the stems and leaves separately. The stems are thicker and will need more time to cook until tender compared to the more delicate leaves.