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

Rhubarb leaves are considered inedible due to their high concentration of oxalic acid. In fact, both the stalks and leaves contain oxalic acid, but the leaves have a much higher content.

At least one death was reported in the literature, an event that rhubarb has yet to live down. Oxalic acid does its dirty work by binding to calcium ions and yanking them out of circulation.