Medically reviewed by Mary Choy, PharmD Oxalic acid, or oxalate, is a naturally occurring organic compound in plant foods like vegetables, fruits, grains, and nuts. Your body also produces small ...

Oxalic acid, or oxalate, is a compound in many plant foods. In large quantities, it can inhibit the absorption of some nutrients. Learn more.

To use oxalic acid, mix one-half cup of the powder in a gallon of warm water and mop it on the stain. Let it work for five to 10 minutes, keeping the stain wet, then scrub with a stiff-bristled ...