Hi @sunnyflower, Yes I have numbness in my feet and a little above my ankles. It was a little below my knees when I started taking the Protocol. I've not seen any studies saying S-ALA is just as effective as R-ALA or na-R-ALA which is what the protocol uses. It would be interesting to find out what your neurologist cited. Here's just one of many articles I've read supporting using R-ALA. I'm no chemist or expert but it's my understanding the S-ALA is the synthetic byproduct of producing R-ALA so it's cheaper not to remove it. I could be way off base though.

(R)-Lipoic Acid: Unique ‘Mitochondrial Antioxidant’ Fights Premature Aging: https://nutritionreview.org/2019/07/r-lipoic-acid-unique-mitochondrial-antioxidant-fights-premature-aging/