nutrition science

oxalic acid, de.: Oxalsäure

Oxalic acid is an organic acid. Spinach, beetroot, chard, rhubarb, wholemeal products and potatoes contain considerable amounts of oxalic acid.

Together with calcium it forms nonsoluble calcium oxalate crystals in the intestinal lumen (the intestinal cavity). Food that is rich in oxalic acid therefore blocks the absorption of calcium. A high concentration of oxalic acid in the body may heighten the risk of kidney stones. If the intake of oxalic acid is high, the calcium concentration in the blood drops, which may cause problems with the blood coagulation.