Hi Val,

Oxalic acid occurs in many plants and is toxic in very large amounts. Some
of the plants that contain a significant amount of oxalic acid are spinach,
collards, and rhubarb. Because oxalic acid binds with calcium and iron, it
inhibits their absorption by the body and is not well-assimilated.

If a person is having difficulty with his, symptoms can occur like kidney
stones and vulvar pain  in women.

Siobhan