Well a few months ago I would have confidently said r-ala is better due to it's effect of lowering plasma insulin, as I have been told by several on this board. Although I don't know if 100mg would be more beneficial at glucose disposal than 500mg racemic ala. If you would have said 300mg, I would have again confidently said the 100mg of r-ala is better. So what's different now? I don't know if you read/post at bb.com, but if you do you would have seen a long long post comparing the two. Alot of interesting points were brought up.
Here some examples (paraphrased - not exact quotes):
- since ALA does not lower plasma insulin but does speed up glucose disposal, hypoglycemia is more likely with it than with R-ALA due to quicker clearing of blood glucose coupled with high insulin levels (seems like a point for r-ala)
- r-ala does not have the beneficial effects that insulin does on protein synthesis, and one of r-ala's effects is to lower insulin
there was also mention of ala behaving as a pro-oxidant (increasing oxidation), although I cannot remember which enatiomer (S or R) this pertained to, but I do know that the blood the dosage to acheive the blood concetrations in the study would have be more than any person would take.
So to kind of answer your question, I don't really know which is better, and I guess it really depends on what you use it for. For anyone who is insulin resistant, I think R-ALA would be better because it not only increases insulin sensitivity to aid in glucose disposal, but also lowers insulin. Aside from that, I'm not so sure I can say which is better.