Malic acid (also known as hydroxysuccinic acid) is an organic acid that plays a role in the complex series of reactions (Krebs' cycle) by which sugars, fatty acids, and amino acids are metabolized to release energy. Manufactured in the body from fumaric acid, malic acid is also found in a variety of fruits and vegetables, with apples and wine being particularly good sources. It is also available as a dietary supplement.
Fibromyalgia studies have used doses ranging from 1,200 to 2,400 mg of malic acid (combined with 300 to 600 mg of magnesium) per day. Malic acid has low toxicity and appears to be well tolerated at this dosage range.