Understanding Oxalates: What Are They and Why Do They Matter?
Oxalates, or oxalic acid, are naturally occurring compounds found in many plants, including fruits, vegetables, grains, and nuts. They are often referred to as 'antinutrients' because they can bind with minerals like calcium, inhibiting their absorption by the body. In some individuals, particularly those prone to kidney stones, a high intake of oxalates can increase the risk of calcium oxalate kidney stone formation. Most oxalates are excreted by the kidneys, but a high load can be problematic. Oxalates exist in two forms: soluble and insoluble. Soluble oxalates are generally considered more readily absorbed by the body, posing a greater risk, while insoluble oxalates (typically bound to calcium) are less bioavailable.
Is Amaranth High in Oxalates? The Verdict
Research confirms that amaranth, especially the leafy greens, is a high-oxalate food.
Amaranth Greens vs. Grains
- Amaranth Greens: Studies on leafy amaranth varieties, such as Amaranthus gangeticus and red amaranth, have found extremely high levels of total oxalates. Some reports indicate values far exceeding 1,000 mg per 100g of raw leaves (on a fresh weight basis). A significant portion of this is water-soluble oxalate, which is more readily absorbed by the body.
- Amaranth Grains: While the oxalate content in the grains is lower than in the leaves, it is still considered high compared to many other grains. However, a larger proportion of the oxalate in the grain is in the insoluble, or calcium oxalate, form. This means it is less bioavailable to the body and less likely to interfere with mineral absorption.
Comparing Amaranth to Other High-Oxalate Foods
To put amaranth's oxalate content into perspective, it helps to compare it with other well-known high-oxalate foods like spinach. Both amaranth greens and spinach are notoriously high in oxalates, but specific levels can vary significantly depending on the cultivar and growing conditions.
| Food (raw) | Typical Oxalate Content (mg/100g) | Notes |
|---|---|---|
| Amaranth Leaves | >1,000 | Can be exceptionally high, often exceeding spinach. |
| Spinach | 600–1,200 | A well-documented high-oxalate vegetable. |
| Rhubarb | 200–500 | Contains high levels of soluble oxalates. |
| Swiss Chard | 400–700 | Another leafy green known for its high oxalate content. |
How to Reduce Oxalates in Amaranth
For individuals concerned about oxalate intake, several cooking methods can help minimize the content in amaranth, especially the soluble oxalates in the leaves.
Effective Cooking Methods
- Boiling: This is the most effective method for reducing soluble oxalate levels. Since soluble oxalates are water-soluble, they can be leached out of the food and into the boiling water. To maximize reduction, use a large volume of water and discard it after cooking. Studies have shown that boiling can remove between 30% and 87% of soluble oxalates in vegetables.
- Soaking: Soaking amaranth leaves or grains before cooking can also help leach some soluble oxalates. Soaking grains overnight and then cooking them can decrease total and soluble oxalate content.
- Cooking with Calcium: Adding a calcium source, such as milk, calcium salts, or calcium-rich vegetables, while cooking can help. The free calcium ions bind to the soluble oxalates, forming insoluble calcium oxalate, which is not absorbed by the body.
Other Techniques
- Fermentation: The fermentation process, often used in many cultures, can help break down oxalates through microbial activity. Controlled fermentation has been shown to reduce oxalate levels significantly.
- Combining with Calcium-Rich Foods: Pairing amaranth with other calcium-rich foods can further reduce the bioavailability of soluble oxalates during digestion. The calcium binds to the oxalates, preventing them from being absorbed.
The Benefits of Amaranth Despite High Oxalates
Despite its high oxalate content, amaranth offers a wide array of nutritional benefits that should not be overlooked.
Nutritional Advantages
- Complete Protein Source: Amaranth grain is a complete protein, containing all nine essential amino acids, including a high level of lysine, which is often low in other grains.
- Rich in Minerals: Amaranth is an excellent source of important minerals such as manganese, magnesium, phosphorus, and iron. Manganese is crucial for metabolic function, while magnesium supports bone health and neurological function.
- High Fiber Content: Both the grain and the leaves are rich in dietary fiber, which supports digestive health and can help lower cholesterol.
- Gluten-Free: As a pseudocereal, amaranth is naturally gluten-free, making it a valuable addition to gluten-free diets.
- Antioxidant Properties: Amaranth contains beneficial antioxidants, such as phenolic acids, flavonoids, and carotenoids, which have anti-inflammatory effects.
Conclusion
Amaranth, both the leaves and the grain, is undeniably high in oxalates. For most healthy individuals, moderate consumption is unlikely to cause issues, especially when cooked properly to reduce the soluble oxalate content. However, people with a history of kidney stones or other oxalate sensitivities should exercise caution and discuss dietary intake with a healthcare professional. By boiling the leaves and pairing amaranth with calcium-rich foods, you can significantly mitigate the risk associated with its oxalate content while still enjoying its impressive nutritional benefits as a protein, fiber, and mineral source. Overall, amaranth can be a healthy and valuable part of a balanced diet when prepared mindfully.
