ABSTRACT
Despite several analytical methods for the determination of α-LA, there is a lack of data to estimate its daily intake. In general, it can be assumed that the amounts consumed in Western diet are too low to cause an increase of α-LA in plasma and cells. However, consumption of dietary supplements containing 50-600 mg of free α-LA (Shay et al. 2009) leads to a signi‚cant increase in plasma and cells even though the bioavailability of the (R)- and (S)-form has been estimated to be only 38% and 20%, respectively, after a 200 mg dose (Hermann et al. 1996, Teichert et al. 1998). Simultaneous food intake reduces the bioavailability of α-LA (Gleiter et al. 1996). Regarding supplementation, there is a need to determine the border between bene‚cial dose and overdose with regard to human health (Wollin and Jones 2003). For these reasons, analytical methods for the determination of α-LA are important. Still, it is also important to determine DHLA, the reduced form of α-LA, and lipoyllysine (LLys) because they may act as sources of free lipoic acid.
