Malic acid is directly involved in the Krebs cycle, a process that the body uses to obtain energy. The Krebs cycle consists of a series of enzymatic reactions* whose purpose is to obtain energy by breaking down carbohydrates. Malic acid is involved in the energy metabolism of the muscle system by stimulating the production of adenosine triphosphate (ATP), a compound that provides energy to muscle cells.
Malic acid is an effective metal chelator, which means that it can “stick” to toxic metals accumulated in the liver and then eliminate them.
Malic acid may prevent the formation of kidney stones. Malic acid is a precursor to citrate, a substance believed to prevent calcium from binding with other substances in urine that form kidney stones. Malic acid has been found to increase urine pH and citrate levels, making stone formation less likely and may therefore be useful for the conservative treatment of calcium kidney stones [Rodgers 2014, Manfredini 2016].
Malic acid can also be used to boost sports performance. A significant increase in the physical performance in sprinters and long-distance runners has been found after 6 weeks of supplementation combined with physical training [Tyka 2015].
Malic acid may also help alleviate pain and tenderness in people with fibromyalgia [Russell 1995].
* Enzymatic reactions are reactions in the body involving enzymes, which are complex proteins that speed up biochemical reactions.