Source Naturals Magnesium Malate is a compound of magnesium and malic acid. Malic acid is a natural fruit acid that is present in most cells in the body and is an important component of numerous enzymes key to ATP synthesis and energy production. Magnesium is an essential mineral in over 300 enzymatic reactions in metabolism. These reactions include those involved in the Krebs cycle (one of the body's energy production systems), energy storage, the breakdown of fatty acids, protein synthesis, DNA metabolism, neurotransmitter activity, and hormone regulation.