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R-Form Alpha-Lipoic Acid & S-Form Alpha-Lipoic Acid

Question:
I heard the S-form of alpha-lipoic acid is bad for me. Why is it in my supplement?

Answer:
The R-form of alpha-lipoic acid is the active, natural form. The S-form occurs when alpha lipoic acid is synthetically manufactured, creating both the S-form and the active R-form. The S-form is most likely inactive, although some information suggests it may an analgesic effect. For more information, see the What It Is section of our Alpha Lipoic Acid Supplements Review, which includes our Top Picks.

Learn More About Alpha Lipoic Acid Supplements



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COMMENTS

Don15207   June 25, 2017
"The S-form is most likely inactive..."

This is the first I'm hearing this! Is it definitely true?
I recently bought a lot of regular S-form ALA so this is disappointing to say the least.

ConsumerLab.com   June 25, 2017
It would be very unusual to find an S-form only. Are you sure it was not an R-form or a combination of R- and S-?

Don15218   June 28, 2017
The product I bought, "Swanson Ultra Alpha Lipoic Acid 300 mg" does not specify either way. Since the "R-form" form is sold as a seperate, much more expensive variety, wouldn't this one be the cheaper "S-form" only, by default? Thanks.

ConsumerLab.com   June 28, 2017
Hi Don -- It is most likely a combination of R- and S-. Extremely unlikely it would be S- only.

Don15225   June 28, 2017
Perhaps, but in the absence of a specific "mixed R- and S-" label claim -- and, economics being what it is -- wouldn't it make sense for a manufacturer to isolate out expensive R-form during production so it can be used in their specifically labeled "R-" formulation, while leaving the leftover "S-" for the regular (lower grade) unspecified ALA?
Doing so wouldn't violate a labeling claim and improves the bottom line.
Guess only a chemical analysis would tell for sure if this is being done. Future project?

ConsumerLab.com   June 28, 2017
Conceivably, but not in practical terms, Don. Making the the mixed form is not the major expense. Separating them is. It's safe to say that if a product doesn't list the form, assume it's the mixed form.

Don15227   June 28, 2017
OK then.
Quoting from your original answer:
"The S-form occurs when alpha lipoic acid is synthetically manufactured, creating both the S-form and the active R-form."

What is the ratio of S- to R- resulting from the synthetic manufacture of ALA? If there's not a significant amount of R- and the S- is inactive(?) may have to consider dumping this and purchasing the R- only type.

ConsumerLab.com   June 28, 2017
It will be half in the R form and half in the S form, Don.

Don15230   June 29, 2017
Thank you. Greatly appreciate the discussion.


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This CL Answer initially posted on 6/23/2017. Last updated 6/25/2017.
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