In the body, oxalic acid combines with divalent metallic cations such as calcium (Ca²⁺) and iron(II) (Fe²⁺) to form crystals of the corresponding oxalates which are then excreted in urine as minute crystals.
These oxalates can form larger kidney stones that can obstruct the kidney tubules.
An estimated 80% of kidney stones are formed from calcium oxalate.
Those with kidney disorders, gout, rheumatoid arthritis, or certain forms of chronic vulvar pain (vulvodynia) are typically advised to avoid foods high in oxalic acid.
Methods to reduce the oxalate content in food are of current interest.

Magnesium (Mg²⁺) oxalate is 567 times more soluble than calcium oxalate, so the latter is more likely to precipitate out when magnesium levels are low and calcium and oxalate levels are high.
Magnesium oxalate is a million times more soluble than mercury oxalate.
Oxalate solubility for metals decreases in the order Mg > Ca > Cd > Zn > {Mn, Ni, Fe, Cu} > {As, Sb, Pb} > Hg.

The highly insoluble iron(II) oxalate appears to play a major role in gout, in the nucleation and growth of the otherwise extremely soluble sodium urate.
This explains why gout usually appears after age 40, when ferritin levels in blood exceed 1 μg/L. Foods high in oxalate should be avoided by people suffering from, or at risk of gout.

Cadmium catalyzes the transformation of vitamin C into oxalic acid.
This can be a problem for people exposed to high levels of cadmium in their diets, in the workplace, or through smoking.

In studies with rats, calcium supplements given along with foods high in oxalic acid can cause calcium oxalate to precipitate in the gut and reduce the levels of oxalate absorbed by the body (by 97% in some cases).

Oxalic acid can also be produced by the metabolism of ethylene glycol ("antifreeze"), glyoxylic acid, or ascorbic acid (vitamin C).

Powdered oxalate is used as a pesticide in beekeeping to combat the bee mite.

Some fungi of the genus Aspergillus produce oxalic acid.

Some preliminary evidence indicates the administration of probiotics can affect oxalic acid excretion rates in a positive manner.
In the body, oxalic acid combines with divalent metallic cations such as calcium (Ca²⁺) and iron(II) (Fe²⁺) to form crystals of the corresponding oxalates which are then excreted in urine as minute crystals. These oxalates can form larger kidney stones that can obstruct the kidney tubules. An estimated 80% of kidney stones are formed from calcium oxalate. Those with kidney disorders, gout, rheumatoid arthritis, or certain forms of chronic vulvar pain (vulvodynia) are typically advised to avoid foods high in oxalic acid. Methods to reduce the oxalate content in food are of current interest.
Magnesium (Mg²⁺) oxalate is 567 times more soluble than calcium oxalate, so the latter is more likely to precipitate out when magnesium levels are low and calcium and oxalate levels are high. Magnesium oxalate is a million times more soluble than mercury oxalate. Oxalate solubility for metals decreases in the order Mg > Ca > Cd > Zn > {Mn, Ni, Fe, Cu} > {As, Sb, Pb} > Hg.
The highly insoluble iron(II) oxalate appears to play a major role in gout, in the nucleation and growth of the otherwise extremely soluble sodium urate. This explains why gout usually appears after age 40, when ferritin levels in blood exceed 1 μg/L. Foods high in oxalate should be avoided by people suffering from, or at risk of gout.
Cadmium catalyzes the transformation of vitamin C into oxalic acid. This can be a problem for people exposed to high levels of cadmium in their diets, in the workplace, or through smoking.
In studies with rats, calcium supplements given along with foods high in oxalic acid can cause calcium oxalate to precipitate in the gut and reduce the levels of oxalate absorbed by the body (by 97% in some cases).
Oxalic acid can also be produced by the metabolism of ethylene glycol ("antifreeze"), glyoxylic acid, or ascorbic acid (vitamin C).
Powdered oxalate is used as a pesticide in beekeeping to combat the bee mite.
Some fungi of the genus Aspergillus produce oxalic acid.
Some preliminary evidence indicates the administration of probiotics can affect oxalic acid excretion rates in a positive manner.
Oxalate