Oxalic Acid: The Health Risks From the Acid

Oxalic Acid

Oxalic Acid: Oxalic acid is a natural substance found in many plants. If you ingest too much, kidney stones can develop. Above a certain dose, it is even fatal.

Vegetables are healthy all round. Many people think that it is full of positive ingredients. However, some plants have risks, such as oxalic acid and its salts, the oxalates. Some varieties, including rhubarb, chard or spinach, contain them naturally. These substances also occur naturally in the human and animal body. They are formed through metabolic processes, mainly through the breakdown of amino acids and ascorbic acid.

In your organism, certain intestinal bacteria break down most of the oxalates. They are excreted through the intestines and kidneys. If you consume too much oxalate-containing foods, your mineral balance can become unbalanced, which can cause your bones and heart to suffer. On the other hand, kidney and bladder stones can form.

The Following Foods Contain Oxalic Acid:

The oxalic acid content of foods fluctuates due to various factors, for example the time of harvest, the part of the plant, the type of preparation. The table shows you mean values:

Oxalate content in Milligrams per 100 grams

  • Rhubarb, steamed (620)
  • Sorrel (500)
  • Purslane (1300)
  • Star fruit (500)
  • Swiss chard (600)
  • Spinach (950)
  • Parsley (170)
  • Cocoa (700)
  • Beetroot, cooked (70)
  • Cassava (1260)
  • Tea (100)
  • Peppermint Leaves (1100)
  • Wheat Bran (450)

The Health Risks From The Acid:

Mineral Robbers: Oxalic acids bind minerals such as calcium, iron and magnesium from food. As a result, the intestinal mucosa can only absorb the minerals to a limited extent. For example, if you suffer from iron deficiency, you should avoid foods that are high in oxalic acid. If oxalic acid interferes with calcium absorption, it can increase your risk of osteoporosis and, in severe cases, even damage the heart.

Kidney and bladder stones: The kidneys excrete part of the oxalic acid that you ingest with food. But it can also bind to the body’s own calcium. The calcium oxalate crystals then infiltrate the vessel walls and may cause:

  • Blockages in the kidneys
  • Bleeding and cell death
  • Anuria (decreased urine production)
  • Renal failure
  • Uremia (urinary poisoning)
  • Disturbances in the electrolyte area

Those who are prone to kidney stones (calcium oxalate stones) should better avoid foods that contain a lot of the substance. About 75 to 85 percent of all kidney stones consist of calcium oxalate, whereas only about ten percent consist of uric acid.

Lethal Dose: if consumed in large quantities, oxalic acid can cause symptoms of poisoning and even be fatal. However, this requires a very high dose of 600 milligrams per kilogram of body weight. The literature cites a case in which a man ate sorrel soup containing 500 grams of sorrel (about six to eight grams of oxalic acid) and died from it.

In This Way You Can Reduce the Oxalic Acid Content:

  • Only eat the parts of the plant that are less contaminated with oxalic acid, i.e. only the stalks of the rhubarb, but not its leaves.
  • Cook vegetables containing oxalic acid before consuming them. During the process, part of the substance is transferred to the boiling water. Then pour it away.
  • Enjoy vegetables that contain the acid along with foods containing calcium. Prepare purslane salad, for example, with a cream sauce or eat cheese with it. Then the calcium binds the oxalic acid. Drink tea with milk for the same reason.


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