Is this the R-ALA (Alpha lipoic acid) or the RS-ALA? Alpha lipoic acid exists in two stereoisomers, the biologically active R-ALA, in addition to S-ALA, which is not produced in the human body. R-alpha lipoic acid is produced synthetically, and chemical manufacturing processes yield both the R- and S- isomers. The racemic RS- form is more inexpensive to refine, as a result. Which one is this?