Has anyone tried Quatrefolic methylfolate? How does it compare to other brands? It seems like it's supposed to be better. Metabolic Maintenance is selling two types of methylfolate(5-MTHF), but their Quatrefolic one is $20 more. Quatrefolic, pure S isomer methylfolate glucosamine salt, has been proven to have greater stability, solubility and bioavailability than any other form of 5-MTHF.