NOW AlphaSorb-C™ includes Transport C-PLUS®, the trademarked blend of Threonic Acid Enhanced Buffered (non-acidic) calcium Ascorbate and Alpha Lipoic Acid. Threonic Acid (a Vitamin C metabolite) has been shown to enhance cellular uptake of Vitamin C. Alpha Lipoic Acid is an antioxidant known to help regenerate Vitamin C in the body. Furth