Fumaric acid, also known as corydalic acid or lichenic acid, is fumaric acid (IUPAC name: (E)-butenic acid), a colorless, flammable crystal, a carboxylic acid derived from butene. Its chemical formula is C4H4O4. Burning fumaric acid releases irritating maleic anhydride fumes. It is a participant in the citric acid cycle, has a fruity odor, and can be found in *Corydalis*, *Boletus*, lichens, and Icelandic seaweed.
Fumaric acid is used in the manufacture of polyester resins and polyols, as well as as a mordant in dyes and a flavoring agent. It is a common food additive and dietary supplement, and is sometimes used as a substitute for tartaric acid in beverages or baking powders.
Biology: Cells use fumaric acid to produce energy from food. Human skin also naturally produces fumaric acid when exposed to sunlight.
Pharmacological Actions
Since psoriasis is sometimes attributed to a deficiency in the production of fumaric acid in the skin, fumaric acid is sometimes used to treat this condition. The initial dose is 60-105 mg daily, gradually increasing to 1290 mg daily. Side effects of fumaric acid use include kidney or digestive problems, and skin redness, often due to overdose. Prolonged use may lead to leukopenia.
Food Uses
Since 1946, fumaric acid has been used as a food acidifier due to its non-toxicity. It is widely used in beverages and baking powders that emphasize purity, such as Viagra grape juice. It is also commonly used as a substitute for tartaric acid, and sometimes as a substitute for citric acid. To maintain a similar taste to citric acid, the ratio of fumaric acid to citric acid is 0.91g to 1.36g.