What are Oxalates and Why Reduce Them?
Oxalates, or oxalic acid, are naturally occurring compounds found in many plant-based foods, including fruits, vegetables, and nuts. For most people, consuming oxalates in moderation poses no significant health risk. However, for individuals sensitive to oxalates, those prone to kidney stones, or those with certain gut issues, excess oxalate intake can lead to problems. Oxalates bind to minerals like calcium and magnesium in the digestive tract, potentially reducing their absorption. In the kidneys, a high concentration of oxalates combined with low fluid intake can lead to the formation of painful calcium oxalate kidney stones. For these individuals, preparing nuts to reduce their oxalate load is a sensible dietary practice.
Practical Methods to Remove Oxalates from Nuts
There are several culinary techniques that can effectively reduce the oxalate content of nuts, primarily by leaching the water-soluble oxalates into a liquid that is then discarded.
The Soaking Process
Soaking is a traditional method that helps reduce anti-nutrients, including oxalates, and can also improve digestibility. It involves submerging raw nuts in water for a period of time, which allows the soluble oxalates to leach out.
Steps for soaking nuts:
- Place the desired quantity of raw nuts in a bowl.
- Cover the nuts with warm water, ensuring they are completely submerged. For every one cup of nuts, use at least two to three cups of water. Some sources suggest adding a pinch of salt to the water.
- Soak for several hours, typically overnight, or for a minimum of 4-6 hours.
- Strain the nuts and thoroughly discard the soaking water. It is crucial not to use this water, as it now contains the leached oxalates.
- Rinse the nuts well under running water.
- Dry the nuts. You can dehydrate them in an oven at a low temperature (around 150°F / 65°C) for a few hours, or use a food dehydrator until they are completely dry and crunchy.
Boiling and Rinsing
Boiling is one of the most effective methods for removing oxalates from high-oxalate foods like leafy greens, and it can also be applied to nuts. Studies have shown that boiling can significantly reduce soluble oxalates.
Steps for boiling nuts:
- Bring a pot of water to a boil.
- Add the nuts and boil for several minutes (10-15 minutes is often recommended, but shorter times may still help).
- Drain the nuts completely and discard the boiling water immediately. The water will contain a significant portion of the leached oxalates.
- Rinse the nuts with fresh water.
- Dry the nuts by patting them with a paper towel or by dehydrating them at a low temperature to restore their crunchy texture.
Pairing with Calcium-Rich Foods
While this method does not remove oxalates from the nuts themselves, it is a highly effective strategy to prevent oxalate absorption in the body. When consumed with calcium-rich foods, the oxalates bind to the calcium in the gut before they can be absorbed into the bloodstream. This creates an insoluble compound that is simply excreted as waste.
Examples of calcium-rich pairings include:
- Adding almonds to a meal with dairy products like yogurt or cheese.
- Having a small portion of cashews with leafy greens or fortified foods.
- Using a calcium citrate supplement with an oxalate-rich meal, as citrate can also bind to oxalates.
Making Smarter Nut Choices
For those on a strict low-oxalate diet, opting for nuts that are naturally lower in these compounds can simplify meal preparation. Different nut types have varying oxalate concentrations, with some being significantly higher than others.
Comparison of Oxalate Levels in Nuts
| Nut Type | Oxalate Level (per 100g) | Notes |
|---|---|---|
| Almonds | ~369 mg | Very high oxalate content. Preparation is recommended for sensitive individuals. |
| Cashews | ~249 mg | High oxalate content. |
| Pine Nuts | ~185 mg | Moderate-high oxalate content. |
| Walnuts | ~62 mg | Low oxalate content compared to almonds. A better choice for low-oxalate diets. |
| Macadamia Nuts | ~42 mg | Extremely low oxalate content, making them one of the best choices. |
By choosing lower-oxalate nuts like macadamias, walnuts, and pecans, individuals can still enjoy the nutritional benefits of nuts without significantly increasing their oxalate load.
Other Factors and Considerations
Fermentation: The fermentation process, often used to produce nut-based yogurts or cheeses, can also reduce oxalate content through microbial and enzymatic activity. While less common for home nut preparation, it's another method for reducing anti-nutrients.
Hydration: Staying well-hydrated is crucial for anyone managing oxalate levels, especially those with a history of kidney stones. Drinking plenty of water helps to dilute oxalate concentrations in the urine, reducing the risk of crystal formation.
Roasting vs. Boiling: While dry heat from roasting or baking may slightly reduce oxalates, it is much less effective than wet cooking methods like boiling or soaking. Since oxalates are water-soluble, they require water to leach out of the food.
Individual Sensitivity: The importance of reducing oxalates in nuts depends on individual health needs. Most people do not need to take these steps, but for those with a known sensitivity or medical condition like hyperoxaluria, it can be an important dietary modification. Consulting a healthcare professional or registered dietitian is always recommended for personalized advice.
Conclusion
For those seeking to reduce their oxalate intake, preparing nuts through soaking or boiling is a highly effective strategy. Soaking helps leach soluble oxalates into the water, while boiling provides a more intense leaching effect. Pairing high-oxalate nuts with calcium-rich foods is another clever way to mitigate absorption in the gut. By understanding how do you remove oxalates from nuts and implementing these simple culinary techniques, you can enjoy the nutritional benefits of nuts while minimizing potential health risks associated with high oxalate levels. For maximum convenience, selecting naturally low-oxalate nuts like macadamias and walnuts is the simplest solution. As with any significant dietary change, moderation and professional guidance are key to ensuring a healthy and balanced diet.
Outbound Link
For more detailed information on managing kidney stones through diet, consult the National Kidney Foundation's resource page on kidney stone diet and prevention.
