Oxalic acid is a metabolite of organisms and a strong acid, which is widely distributed in plants, animals and fungi and plays different roles in different life forms. It is found that 100 plants are rich in oxalic acid, especially spinach, amaranth, beet, purslane, taro, sweet potato and rhubarb.

Metabolites, also known as intermediate metabolites, refer to substances produced or consumed through metabolic processes, excluding biological macromolecules. Metabolites, also known as intermediate metabolites, refer to substances produced or consumed through metabolic processes, excluding biological macromolecules. The precursors and degradation products of biomacromolecules are real metabolites.