Researchers speak about the two Lipoic Acids
 
"We're finding - and others are, too - that the R(+)-form - the natural form - is much more powerful than the racemic mixture ... Hopefully ... companies are going to be producing on more of a clinical scale the R(+)-form of lipoic acid, because we're finding very significant effects using this, as opposed to the racemic mixture."
Dr. Tory Hagen, in Mitochondrial Decay in Aging.

"We have presented in this study new information indicating that this enhancement of glucose metabolism is sterospecific, with the R(+)-enantiomer being much more effective than the S(-)- enantiomer."
Dr. Ryan Streeper and colleagues, in The American Journal of Physiology.

"Lipoic acid sold in a health food store is a synthetic mixture, a racemic mixture. And R[+]- is the natural form and S[-]- is an unnatural one ... And in our hands R[+]- works and S[-]- doesn't."
Dr. Bruce Ames, in Strategies for Engineered Negligible Senescence.

"R[+]-LA [that is, R(+)-lipoic acid], and not a racemic mixture of R[+]-and S[-]- LA, should be considered a choice for therapeutic applications."
Dr. Lester Packer and colleagues, in Free Radical Biology and Medicine.

"The S[-]-enantiomer … part of the racemate, which is present as about a 50% impurity, needs to be eliminated."
Dr. Guido Zimmer and colleagues, in Methods in Enzymoogy.