Alpha lipoic acid is a molecule that has one chiral center, a carbon atom with 4 different groups attached to it. This means that it has the possibility of existing in 2 different optical isomers. These two different isomers are designated either R-alpha lipoic acid or S-alpha lipoic acid. RS alpha lipoic acid is a mixture of both forms.
Pure Encapsulations alpha lipoic acid is RS, a combination of 70 % R and and 30% S forms.
Recently, R-alpha lipoic acid has been suggested as being the superior form of alpha lipoic acid. Below are several considerations supporting the continued use of an RS combination.
- Many of the studies promoting the effects of R lipoic acid were conducted in cellular or rat studies and examined the activity of the R isomer alone (not in comparison to S or more importantly, to RS).
- Of the studies that compared the R isomer with other alpha lipoic acid configurations, most were R vs. S rather than R vs. RS. This is an important distinction since R may have properties that differ from S, but this does not necessarily translate to R being more effective than an RS preparation.
- In the handful of studies that compared R vs. S vs RS, R and RS were superior to S. There does not seem to be enough evidence at this time to say that R is significantly more effective than RS. It may be significantly more effective than S alone, but not necessarily more effective than RS.
- Several studies indicate comparable effects of R vs. RS.
- R-alpha lipoic acid is an unstable molecule when isolated.
- R-alpha lipoic acid costs 5-7 times as much as RS.
Pure Encapsulations Alpha Lipoic Acid is 99% pure and has the lowest impurity profile on the market.
