Oxalic Acid

Oxalic acid is a chemical compound that has the simplest structure of all dicarboxylic acids. The salt of this ubiquitous acid is called oxalate (ethanedioate).

History of oxalic acid

Oxalic acid was first discovered in 1769 by the German pharmacist Johann Christian Wiegleb in the plant Oxalis (Oxalis acetosella, from which the name "oxalic acid" is derived). It was synthesized from inorganic compounds by the chemist Friedrich Wöhler in 1924.

Plants with high contents of oxalic acid are:

A nutrition with high consumption of oxalic acid-rich food can lead to the production of kidney stones. This is because metal ions like calcium form insoluble precipitates with oxalate (calcium oxalate). Calcium oxalate is responsible for 75% of all kidney stones.

Measures to reduce the content of oxalic acid

Example: rhubarb

Since the leaves of rhubarb have the highest content of oxalic acid, only the stalks are eatable. So it is recommended to remove the leaves and to clean and peel the rhubarb. If you blanch it (plunge it into boiling water), a part of the oxalic acid gets into the cooking water (as of course do the water soluble vitamins like vitamin c).

Oxalic acid-rich food and diary products

As mentioned above, the consumption of oxalic acid-rich food and diary products leads to the production of oxalate which can hardly be absorbed by the intestine. For persons who must pay attention to a low oxalic acid diet, this is a proper way to reduce the content of this acid.

But, as the absorption of the valuable calcium is also reduced, this method is less recommended for people who require a calcium-rich diet (e.g. for the therapy or prevention of osteoporosis).

Read more why you should not pick rhubarb after June.

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