Alpha-lipoic acid (ALA, thioctic acid) is a naturally occurring vitamin-like nutrient that has been intensely investigated as a therapeutic agent for a variety of conditions involving the body’s nervous, cardiovascular, immune, and detoxification systems. It exists as two enantiomers or stereoisomers: R-(+)-lipoic acid (RLA) and S-(-)-lipoic acid (SLA). It is produced in small amounts in the liver and other body tissues, where it is needed by enzymes to catalyse numerous essential chemical reactions in the body. For instance, ALA is essential inside the mitochondria of cells, where it is needed to metabolise glucose and direct calories into energy production.
ALA is considered to be a multimodal supplement because, aside from its enzymatic role in energy production, it acts by multiple mechanisms and displays diverse pharmacologic and antioxidant properties. Recently discovered is ALA’s ability to switch the regulation of several genes linked to cell survival, inflammation and oxidative stress. So in addition to its enzymatic role, ALA is a powerful antioxidant and performs a number of other vital functions related to its ability to modify the expression of various genes. ALA is therefore not so much a direct benefit to cells, but rather an indirect aid that "kick starts" declining function in cells, helping them recover the functions that came more easily and naturally in the young.