Understanding Oxalates and Their Impact
Oxalates, or oxalic acid, are natural compounds found in many plant-based foods, including fruits, vegetables, nuts, and seeds. In most individuals, oxalates are simply processed and excreted by the body without issue. However, for people with a history of kidney stones, particularly the calcium oxalate type, or other related health conditions, high oxalate intake can be problematic.
When consumed, soluble oxalates can bind with calcium in the urine, forming hard mineral deposits known as kidney stones. While almonds are a nutritious source of healthy fats, protein, and minerals, their high oxalate concentration means that moderating intake or employing reduction techniques can be beneficial for at-risk individuals. The effectiveness of these techniques largely depends on the water solubility of oxalates, which allows them to be leached out or removed.
Effective Methods for Reducing Almond Oxalates
For home preparation, the most effective ways to lower the oxalate content in almonds involve either soaking them in water or blanching to remove the skins. Both methods work by utilizing the solubility of oxalates.
Step-by-Step Guide to Soaking Almonds
Soaking is a simple and traditional method that helps reduce soluble oxalates and softens the nuts, potentially improving digestibility.
- Measure and Clean: Start with raw, unroasted almonds. Measure your desired portion and place them in a bowl.
- Add Water: Cover the almonds with warm tap water. Some sources suggest adding a pinch of salt to aid the process.
- Soak Overnight: Let the almonds soak for 8 to 12 hours, or overnight, on the countertop.
- Drain and Rinse: Drain the soaking water thoroughly. This is a critical step, as the water now contains the leached oxalates and should be discarded.
- Enjoy or Dry: Your soaked almonds are now ready to eat, or you can dry them in a dehydrator or a low-temperature oven to restore their crunch.
Step-by-Step Guide to Blanching and Peeling
Blanching is particularly effective because a significant portion of the oxalates in almonds resides in the brown skin or pellicle. Removing this layer substantially reduces the nut's oxalate load.
- Boil Water: Bring a small pot of water to a rolling boil.
- Add Almonds: Carefully add raw almonds to the boiling water and let them simmer for exactly 60 seconds. Boiling longer can make them soft and soggy.
- Shock with Cold Water: Immediately drain the almonds and plunge them into a bowl of ice-cold water. This stops the cooking process and loosens the skins.
- Remove Skins: Gently pinch each almond between your fingers. The skin should slide off easily.
- Dry: Pat the blanched, peeled almonds dry with a clean towel. They can be toasted for flavor or used immediately in recipes.
Nutritional Considerations Beyond Oxalates
While effective for oxalate reduction, soaking and blanching do have other nutritional effects. Soaking can reduce levels of other anti-nutrients like phytic acid, which can improve the bioavailability of certain minerals. However, research on the mineral loss in almonds specifically is mixed, with some studies showing a slight decrease in mineral concentration after soaking. The almond skins also contain antioxidants like polyphenols, which are lost during blanching. The best approach depends on individual health goals and preferences, weighing the benefits of lower oxalates against potential minor nutrient trade-offs.
The Importance of Calcium in Reducing Absorption
For those who choose to consume almonds with their skins, or even after a reduction process, a proven strategy to limit oxalate absorption is to pair them with calcium-rich foods at the same meal. Calcium binds with oxalate in the gut before it can be absorbed into the bloodstream. This creates an insoluble compound that is then excreted from the body in the stool rather than traveling to the kidneys.
Good pairings for calcium include:
- Yogurt or cheese.
- Leafy greens high in calcium but low in oxalates, like kale.
- A calcium supplement taken with the meal.
This simple dietary tactic can significantly lower the load on the kidneys and is a key recommendation for managing oxalate intake.
Comparing Almond Products
The oxalate content isn't consistent across all almond products. Processing significantly alters the final oxalate concentration.
How Processing Affects Almond Oxalate Content
| Product | Processing | Typical Oxalate Content (approx.) | Notes |
|---|---|---|---|
| Raw Almonds | None | ~122 mg per ounce | High in oxalates, especially in the skin. |
| Soaked Almonds | Soaked 8-12 hrs, water discarded | Reduced (percentage varies) | Softened, potentially improved digestibility. |
| Blanched Almonds | Briefly boiled, skins removed | Significantly reduced | Very effective reduction; skins contain highest concentration. |
| Almond Flour | Finely ground, often blanched almonds | High (~140-400 mg per 1/2 cup) | Concentrated source of oxalates, as it takes many almonds to make. |
| Commercial Almond Milk | Soaked, blended, strained | Low (30-50 mg per cup) | Straining removes solids, significantly lowering oxalate levels. |
| Homemade Almond Milk | Soaked, blended, strained | Varies (Can be higher) | Depends on the soaking time and effectiveness of straining. |
Low-Oxalate Almond Alternatives and Best Practices
For individuals with a high sensitivity to oxalates, or those who find soaking and blanching too cumbersome, exploring other low-oxalate nut options can be a good strategy. Nuts like macadamia nuts, pecans, and walnuts contain significantly lower amounts of oxalates compared to almonds. Seeds like pumpkin and sunflower seeds are also low-oxalate options.
Regardless of your nut preference, maintaining adequate hydration is one of the most critical factors in preventing kidney stones. Drinking plenty of water helps flush out excess oxalates before they can form crystals in the kidneys. Always consult a healthcare professional or a registered dietitian before making significant changes to your diet, especially if you have a history of kidney stones or other related conditions.
Conclusion
While raw almonds are a high-oxalate food, individuals can significantly reduce their oxalate intake through simple kitchen techniques. Blanching and peeling the skins is the most effective method, as the skins contain the highest concentration of oxalates. Soaking and discarding the water also helps leach out a portion of the soluble oxalates. For ongoing management, pairing almonds with calcium-rich foods can effectively reduce absorption in the gut. By implementing these practical strategies, you can enjoy the nutritional benefits of almonds while mitigating the risk of high oxalate consumption, especially if you are prone to kidney stone formation. For the lowest oxalate content from almonds, opt for blanched and peeled varieties, and consider low-oxalate alternatives like macadamia nuts if necessary. A balanced approach, combined with proper hydration, is key to incorporating almonds into a healthy, low-oxalate diet.
