You may not have heard of oxalates. Knowing that the oxalic acid that forms them is found in many plants, such as green leafy vegetables, vegetables, fruits, cocoa, nuts and seeds, you will think that they are beneficial compounds, because the problem today is that people don’t eat enough of those foods vegetables.
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However, if we say that the oxalates form 80% of kidney stonesSuddenly they don’t seem so harmless. As is often the case, the danger lies in the extremes.
Oxalate is produced in our own body as waste product of vitamin C metabolism, as well as fructose and the amino acids serine and glycine. The body does not need oxalate at all, and it is eliminated through urine or feces. This means that even if we don’t eat anything that contains oxalates, it will still be present in our urine as a result of the natural workings of our metabolism.
Kidney stones appear when these oxalates, especially calcium, begin to form crystals, aggregating to form the well-known “stones”. Low urine volume (from not drinking enough water) plays an important role in this crystallization.
To people who suffer from kidney stones a low-oxalate diet is recommended, But not in all cases. The reason is that half of the oxalate found in urine is produced by the body, and does not come from food. That’s why You can not say that eating spinach will necessarily cause kidney stones.
Spinach and other foods rich in oxalates are considered healthy and are only restricted in cases where high levels of oxalates are detected in the urine. Here is a list of foods that contain the most oxalates:
- Soy and derivatives.
- Almonds and peanuts.
- Potatoes and sweet potatoes.
Excess oxalates in the diet can also be annoying in other, less obvious ways.
Oxalate as an antinutrient
The fact that oxalate has such an affinity to bind calcium is not only a problem in the case of kidney stones. When we eat foods rich in oxalate, it can combine in our intestines with calcium and other minerals such as magnesium or zinc, and prevent the body from absorbing them, causing deficiencies.
This makes oxalate an antinutrient, that is, a substance that prevents us from absorbing nutrients. For example, spinach is high in calcium, but also in oxalate, which prevents the body from absorbing much of the calcium in spinach. Eat other high-fiber fruits and vegetables at the same time that these sources of oxalate aggravate the situation and there is even less absorption of calcium, magnesium and zinc.
However, in trials it has been seen that, although the calcium in spinach is not well absorbed by oxalate, when taking spinach together with milk, the calcium in milk, which has another molecular form, continued to absorb normally.
This seems to be the key. More and more people are swapping milk for smoothies, green smoothies that mix fruit, large amounts of leafy vegetables like spinach, and soy milk or nuts. That is, a true cocktail of oxalates. These foods are considered very healthy for their contribution in fiber and antioxidants. But if there is no contribution of minerals from other sourcessuch as dairy, fish, or shellfish, or through supplements, there is a risk of mineral deficiencies, especially calcium, caused by oxalates. This is especially important in vegan people.
How to avoid the risks of oxalates without giving up the benefits of vegetables? Here are some solutions:
- Eat foods high in calcium and low in oxalatesuch as cheese, yogurt, fish with bones (anchovies or sardines), bok choy, cauliflower, and broccoli.
- Boil, Blanch and Steam spinach and other greens removes much of the oxalates, especially if the cooking water is discarded.
- Cook or macerate in milk greatly reduces the oxalate content, as well as macerate in vinegar or lemon juice.
- fermentation and germination they can help reduce the oxalate content of soybeans, for example, or beets.
If what worries you is the risk of kidney stones, do not hesitate to consult your doctor and do not forget to drink water.
What is all this based on?