Regular RLA is not well absorbed we are learning.

If you mean RALA (the sodium stabilized variety)...they claim much higher absorption.

Of course measuring it in the serum of the blood, is only a general thing ... the lipoic acid whatever version, will get sucked up into the tissues, and not be in the serum anymore after a short time. I have not seen any test that reveals tissue levels.

I've seen serum levels duration for RALA at 2-3 hrs, and racemic mixed ALA delayed release at 4-6 hrs (from one study). Once the lipoic acid is in the tissue, that is all that matters because that is where it works, in the cells themselves.

There are some sites on the net that claim the inactive S version works against the R... but there is no proof of that.
Also one study on racemic showed lowering of thyroid hormones in rats. No studies yet on humans. No study for R only either.

So there remains some facts still missing. All you can do is watch your responses. I have noticed for myself, less cold intolerance this winter...than last. So perhaps that is from the lipoic I am using now. (Doctor's Best Stablized R)