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Are Oxalic Acid and Oxalates Really Bad?

Many foods considered healthy contain oxalic acid. Leafy greens and other plant-based foods are very popular among those who lead a healthy lifestyle.

However, many of these products contain oxalic acid, which is often regarded as an antinutrient.

In this article, we aim to compile scientific reports to evaluate the health effects of oxalates and their derivatives when consumed.

What is Oxalate or Oxalic Acid?

Oxalic acid is an organic compound that can be found naturally in many plants and vegetables.

These include leafy green vegetables, some fruits, cocoa, seeds such as nuts, and others.

When oxalic acid binds to other minerals, as is often the case in plants, it forms compounds known as oxalates. One of the most well-known forms is calcium oxalate.

Our body can produce oxalates autonomously, but we mostly obtain them through food.

For example, vitamin C can be broken down into oxalates once it undergoes the metabolization process.

In our digestive system, oxalates most frequently bind to minerals such as calcium and iron in the colon, and less frequently in the kidneys and urinary tract.

In most cases, mineral-bound and insoluble oxalates are eliminated through urine or feces. However, sometimes they form deposits in the kidneys and urinary tract, known as kidney stones.

oxalate kidney stones

Oxalate May Reduce Mineral Absorption

Therefore, this element acts as an insolubilizing complexing agent, reducing the ability of many minerals to be absorbed by the body.

When a mineral before reaching the intestine binds with oxalic acid, it can form a precipitate that prevents its absorption.

A well-known case is that of spinach, which contains a high concentration of calcium (but not such high iron) and many oxalates, so there are many difficulties for such calcium to be physiologically active. [Effect on calcium absorption]

The same thing also happens, in parallel, with fiber, which can prevent the assimilation of certain minerals. In addition, binding with oxalates does not happen with all minerals. Only with some specific ones.

Can Oxalic Acid Cause Any Disease?

Scientific trials have ruled out the popular belief that oxalic acid is linked to the onset of autism or chronic vaginal pain (vulvodynia). [View Report]

However, improving the diet by increasing the intake of active calcium not bound by oxalates, along with iron, has led to improvements in the symptoms of several diseases.

Basically, the scientific community confirms that oxalic acid is not the origin of the problem, but it can aggravate the symptoms.

Foods With Oxalates Are Considered Healthy

Foods containing oxalates

Eliminating foods with oxalates from the diet means reducing the intake of foods considered healthy. Most of these foods contain important antioxidants, fiber, and are low in saturated fats.

Therefore, it is not simple to eliminate such foods to reduce the risk of kidney stones, as it may lead to other, more severe health issues.

Some of these foods are as follows:

Seeds and grains:

  • Wheat bran, wheat germ, and barley
  • Corn grits
  • Corn flour
  • Intergral bread


  • Dried apricots
  • Red currants, figs and rhubarb
  • Kiwi


  • Collard greens, leeks, spinach
  • Beans
  • Eggplant
  • Beetroot
  • Chard, endives, parsley and turnip
  • Tomato sauce

Protein foods:

  • Beans stewed with tomato sauce
  • Butter (almonds, walnuts, cashews, hazelnuts, etc.)
  • Miso
  • Beans


  • Fruit cake
  • Chocolate
  • Jams


  • Chocolate drink
  • Soy milk
  • Iced teas

Other foods:

  • Sesame seeds and tahini (paste made from sesame seed)
  • Poppy seeds

Additional Tips

Finally, we’ll provide you with some tips on how to start a low-oxalate diet:

  1. Reduce oxalate intake to a maximum of 50 mg per day.
  2. Boil vegetables rich in oxalates: This can reduce the oxalic acid content by between 30% and 90%, depending on the vegetable.
  3. Drink plenty of water: This increases the dilution of these insoluble compounds and aids in their elimination through urine.
  4. Find a readily absorbable source of calcium.
  5. Ensure sufficient calcium intake: We need between 800 to 1,200 mg of calcium per day. Here are some foods rich in calcium.
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About Andrew Parkinson

Andrew Parkinson is a highly accomplished pharmacist with a passion for improving healthcare. With a wealth of experience in both community and clinical pharmacy settings, he's known for his dedication to patient well-being. Mr. Parkinson actively engages in medication management, offering personalized solutions and promoting better health outcomes. He has also played a pivotal role in educating patients on proper medication usage and potential interactions. Andrew's commitment to advancing the field of pharmacy and ensuring safe and effective drug therapies has garnered him recognition as a trusted and invaluable healthcare professional, making a positive impact on countless lives.

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