Oxalates are naturally occurring compounds found in various plants, including many common fruits, vegetables, nuts, and seeds. They serve as a defense mechanism for the plant itself. While generally harmless for most individuals, oxalates can be a dietary consideration for some people due to their chemical properties.
Understanding Oxalates in Almonds
Almonds contain oxalates as a protective mechanism. These compounds are present in both soluble and insoluble forms. While the insoluble form is less readily absorbed, the soluble oxalate content in almonds is around 122 milligrams per ounce, which is approximately 22 to 26 nuts.
For individuals prone to kidney stone formation, high-oxalate foods can be a concern. Oxalates have the ability to bind with minerals such as calcium in the digestive tract, forming calcium oxalate crystals. These crystals can contribute to the development of kidney stones. This binding can also interfere with the absorption of certain minerals, including calcium and iron, which are vital for overall health.
Proven Methods for Oxalate Reduction
Several practical methods can help reduce the oxalate content in almonds, primarily by leveraging the water-soluble nature of some oxalate forms.
Soaking almonds is a widely recognized method for reducing their oxalate levels. Since oxalates are water-soluble, soaking allows a portion of these compounds to leach into the water. For optimal results, soaking almonds overnight, ideally for around 18 hours, can reduce oxalate concentration by 6.7% to 20%, with some reports suggesting reductions up to 40%. After soaking, it is important to thoroughly rinse and discard the soaking water to remove the leached oxalates. This process also softens the almonds, potentially making them easier to digest.
Blanching, which involves briefly boiling almonds, is another effective technique. This method is particularly useful for reducing oxalates found in the almond skins. Research indicates that a boiling process, such as blanching for about 12 minutes, can lead to a significant reduction in soluble oxalates, ranging from 30% to 87%. The heat and water help to break down and leach out these compounds.
Sprouting almonds can reduce oxalates. The germination process initiated by sprouting can break down anti-nutrients, including oxalates. This method involves soaking the almonds to encourage the beginning of a sprout, after which they are typically rinsed and allowed to dry. Sprouting can also enhance the bioavailability of other nutrients within the almond.
Roasting can reduce oxalate content, particularly the insoluble forms. Studies suggest that roasting can lead to substantial reductions in oxalates, with some research indicating a decrease of 86.7% to 93.3%. This suggests that oxalates are thermolabile, meaning they can be degraded by heat. While roasting alone may be less effective for soluble oxalates compared to water-based methods, it can complement soaking or blanching.
Optimizing Reduction and Nutritional Value
To maximize oxalate reduction, combining methods like soaking followed by blanching or roasting can be beneficial. For instance, soaking almonds overnight before a brief blanching or roasting period can yield more comprehensive oxalate removal. Discarding any water used for soaking or boiling is crucial to ensure the removed oxalates are not re-consumed.
A common concern with these preparation methods is potential nutrient loss. While water-soluble nutrients like some B vitamins and vitamin C might minimally leach into the soaking water, the overall nutritional integrity of almonds remains largely intact. Almonds retain their beneficial healthy fats, protein, fiber, and many vitamins and minerals even after these processes. For individuals who are sensitive to oxalates, the benefits of reducing these compounds often outweigh any minor theoretical nutrient losses. Almonds continue to be a nutrient-dense food that can support a balanced diet.