L-carnitine fumarate is a dietary supplement widely used as a weight loss aid, energy booster, and supporter of cardiac, neurological and muscular function. The supplement is a combination of L-carnitine and fumaric acid, both of which purport to have several health related benefits. L-carnitine is a well-known supplemental amino acid with antioxidant and metabolism boosting qualities. Fumaric acid is an element of the Krebs or citric acid cycle which allows cells to produce energy. In combination in L-carnitine fumarate supplements, the two elements are believed to complement and enhance their beneficial qualities.