How to Remove Oxalates from Seeds Effectively

Over 75% of kidney stones are primarily composed of calcium oxalate. Many seeds, while nutritious, contain high levels of oxalates, which are compounds that can bind with minerals like calcium and potentially interfere with their absorption. Fortunately, several food preparation techniques can effectively help you remove oxalates from seeds and other foods.

Quick Summary

This guide details effective techniques like soaking, sprouting, and fermentation to decrease oxalate content in various seeds. It explains how to implement each method, their effectiveness, and which seeds benefit most from these processes for better mineral absorption.

Key Points

• Soak and Discard: Soaking seeds overnight in water and then discarding the water effectively leaches out soluble oxalates.

• Sprout for Enzymatic Action: Sprouting breaks down antinutrients like oxalates, significantly reducing their levels in seeds.

• Boil After Soaking: For seeds that are cooked, boiling in fresh water after an initial soak can maximize oxalate removal.

• Fermentation Reduces Oxalates: The microbial activity during fermentation effectively degrades oxalates, with studies showing significant reduction.

• Pair with Calcium: Eating high-oxalate seeds with calcium-rich foods can help bind oxalates and prevent their absorption.

Understanding Oxalates in Seeds

Oxalates, or oxalic acid, are naturally occurring compounds in many plants, including a wide variety of nuts and seeds. They serve as a defense mechanism for the plant. For humans, however, oxalates can act as "anti-nutrients" by binding to minerals such as calcium and magnesium in the digestive tract, potentially hindering their absorption. While most people can tolerate oxalates, individuals with a history of kidney stones or certain health conditions may need to reduce their intake.

Seeds High in Oxalates

Different seeds contain varying levels of oxalates. Some of the most notable high-oxalate seeds include:

• Sesame seeds: Often found in tahini, sesame seeds are known to have a higher oxalate content.
• Chia seeds: While celebrated for their health benefits, chia seeds are considered high in oxalates.
• Almonds: Often categorized with seeds for culinary purposes, almonds contain significant oxalate levels, especially when consumed raw and unsoaked.
• Legume seeds: Certain legumes, like soybeans and some bean varieties, contain high oxalate levels.

Methods for Removing Oxalates from Seeds

Various processing methods leverage the water-soluble nature of oxalates to reduce their concentration in seeds. These techniques involve a combination of time, temperature, and microbial activity.

1. Soaking

Soaking is one of the simplest and most accessible ways to reduce antinutrients like oxalates. The soluble oxalates leach out of the seeds and into the soaking water, which should be discarded before consumption or further preparation.

How to soak seeds effectively:

1. Measure your seeds and place them in a bowl.
2. Add a generous amount of fresh water, ensuring the seeds are fully submerged. Use a ratio of at least 1:5 (seeds to water).
3. Soak overnight, or for a minimum of several hours. Some studies suggest soaking for up to 12 hours for greater reduction.
4. Strain the seeds and thoroughly rinse them under running water.
5. Discard the soaking water, as it now contains the leached oxalates.

2. Sprouting (Germination)

Sprouting, or germination, is a process that breaks down antinutrients, including oxalates. It begins with soaking but extends the process to allow the seed to sprout, increasing nutrient bioavailability and digestibility.

How to sprout seeds:

1. Start by soaking the seeds using the method described above.
2. After the initial soak, drain and rinse the seeds thoroughly.
3. Place the seeds in a sprouting jar or a colander covered with a cheesecloth. Keep them out of direct sunlight.
4. Rinse and drain the seeds every 8-12 hours. This provides fresh moisture and prevents mold.
5. After 24 to 48 hours, depending on the seed type, you will see small sprouts. At this stage, the oxalate levels are significantly reduced.
6. Rinse one last time before using.

3. Fermentation

Fermentation uses beneficial microorganisms to break down compounds like oxalates. This method is particularly effective for certain seeds and involves a longer process.

How to ferment seeds:

1. Combine seeds with a brine solution (water and salt) and a culture, if desired.
2. Keep the mixture in a controlled environment for a period of time, as this allows microbial activity to degrade oxalates.
3. Studies have shown that fermentation can lead to significant oxalate reduction, sometimes by over 50%, depending on the duration and microbial activity.

4. Cooking and Boiling

For seeds that are typically cooked, boiling is a highly effective method for removing soluble oxalates. The key is to boil the seeds in plenty of water and then discard the water afterwards.

How to boil seeds for oxalate reduction:

1. First, pre-soak the seeds to maximize the reduction of soluble oxalates.
2. Rinse the soaked seeds and place them in a pot with fresh water.
3. Bring the water to a boil and cook the seeds until they are tender.
4. Drain the seeds and discard the cooking water, which now contains a portion of the oxalates.

Comparison of Oxalate Reduction Methods

Method	Primary Mechanism	Effectiveness	Suitable For	Key Drawback
Soaking	Leaching of soluble oxalates into water	Moderate to High (17-56% reduction)	All seeds, especially legumes before cooking	Only removes soluble oxalates; requires discarding water
Sprouting	Enzymatic degradation of antinutrients	High (can exceed 60% in some seeds)	Most small seeds, like lentils and legumes	Requires several days and consistent rinsing
Fermentation	Microbial degradation of oxalates	High (up to 69% in sesame seeds)	A wide range of seeds; can change flavor profile	Can be complex and requires a controlled process
Boiling	Leaching of oxalates into cooking water	High (especially after pre-soaking)	Seeds that require cooking, such as beans	Requires careful draining and discarding of water

Practical Application and Combination Techniques

For maximum oxalate reduction, combining methods can be highly effective. A common approach is to first soak the seeds to remove a significant portion of soluble oxalates, then boil them in fresh water to further reduce the content. For seeds intended for raw consumption, combining soaking and sprouting is often the best strategy.

Consider the following examples:

• Legumes: Soak overnight, discard the water, and then boil thoroughly in fresh water.
• Sprouts: Soak seeds for 8-12 hours, then follow the sprouting procedure, rinsing regularly until sprouts appear.
• Tahini: For high-oxalate sesame seeds, fermentation or prolonged soaking can be beneficial.

It is important to remember that not all oxalate is absorbed by the body. Pairing high-oxalate seeds with calcium-rich foods can also help bind oxalates in the digestive tract, preventing their absorption. Always consult a healthcare professional or registered dietitian for personalized dietary advice, especially if you have a medical condition that requires a low-oxalate diet.

Conclusion

While seeds are a valuable part of a healthy diet, their oxalate content can be a concern for some individuals. Fortunately, practical and effective food preparation techniques like soaking, sprouting, fermentation, and boiling can significantly reduce oxalate levels. By understanding these methods and their applications, you can enhance the nutritional quality and bioavailability of seeds while minimizing potential risks associated with high oxalate intake. Combining these techniques offers the most comprehensive approach to reducing antinutrients and enjoying the full benefits of seeds.

Frequently Asked Questions

Does soaking alone completely remove oxalates from seeds?

No, soaking primarily removes soluble oxalates, with studies showing a reduction ranging from 17% to over 50%. Combining soaking with boiling or sprouting provides a more significant reduction.

Which seeds have the highest oxalate content?

Some of the seeds with higher oxalate levels include sesame seeds, chia seeds, and certain nuts often used similarly to seeds, such as almonds and peanuts.

Is boiling or steaming more effective for reducing oxalates?

Boiling is generally more effective for reducing oxalates than steaming because the soluble oxalates are leached into the boiling water, which is then discarded. Steaming provides less opportunity for this leaching to occur.

Can I use the soaking water for other things?

No, you should always discard the soaking water. It contains the oxalates that have been leached out of the seeds, so reusing it would re-introduce those compounds into your food.

Does sprouting affect other nutrients in seeds?

Yes, sprouting not only reduces antinutrients but can also increase the bioavailability of minerals and potentially increase antioxidant content and other beneficial compounds.

What is the best way to reduce oxalates in sesame seeds?

For sesame seeds, fermentation has been shown to be highly effective, with studies reporting significant reductions in oxalate content after a period of several days.

How long should I soak seeds to reduce oxalates?

Soaking times can vary by seed type, but overnight or a minimum of 8-12 hours is often recommended to achieve a significant reduction in oxalates.