TitleAge and gender dependent bioavailability of R- and R,S-α-lipoic acid: a pilot study.
Publication TypeJournal Article
Year of Publication2012
AuthorsKeith DJ, Butler JA, Bemer B, Dixon B, Johnson S, Garrard M, Sudakin DL, J Christensen M, Pereira C, Hagen TM
JournalPharmacol Res
Date Published2012 Sep
KeywordsAdult, Age Factors, Aged, Antioxidants, Biological Availability, Dietary Supplements, Female, Glutathione, Humans, Male, Pilot Projects, Sex Factors, Stereoisomerism, Thioctic Acid

Lipoic acid (LA) shows promise as a beneficial micronutrient toward improving elder health. Studies using old rats show that (R)-α-LA (R-LA) significantly increases low molecular weight antioxidants that otherwise decline with age. Despite this rationale for benefiting human health, little is known about age-associated alterations in absorption characteristics of LA, or whether the commercially available racemic mixture of LA (R,S-LA) is equally as bioavailable as the naturally occurring R-enantiomer. To address these discrepancies, a pilot study was performed to establish which form of LA is most effectively absorbed in older subjects relative to young volunteers. Young adults (average age=32 years) and older adults (average age=79 years) each received 500 mg of either R- or R,S-LA. Blood samples were collected for 3h after supplementation. After a washout period they were given the other chiral form of LA not originally ingested. Results showed that 2 out of 6 elder males exhibited greater maximal plasma LA and area under the curve for the R-form of LA versus the racemic mixture. The elder subjects also demonstrated a reduced time to reach maximal plasma LA concentration following R-LA supplementation than for the racemic mixture. In contrast, young males had a tendency for increased bioavailability of R,S-LA. Overall, bioavailability for either LA isoform was much more variable between older subjects compared to young adults. Plasma glutathione levels were not altered during the sampling period. Thus subject age, and potential for varied response, should be considered when determining an LA supplementation regimen.

Alternate JournalPharmacol. Res.
PubMed ID22609537
PubMed Central IDPMC4084596
Grant ListT32AT002688 / AT / NCCIH NIH HHS / United States
AT002034 / AT / NCCIH NIH HHS / United States
P30ES000210 / ES / NIEHS NIH HHS / United States
T32 AT002688 / AT / NCCIH NIH HHS / United States
P01 AT002034 / AT / NCCIH NIH HHS / United States
P30 ES000210 / ES / NIEHS NIH HHS / United States