The “cyanocobalamin” Edition of B12 is comprised of cyanide which as time passes might have toxic consequences, this form of B12 isn't best and for anyone with MTHFR gene mutations, it might most of the time be tougher for their overall body to work with vs other varieties of B12. https://mylesswbfk.blogitright.com/30620097/considerations-to-know-about-vitamin-b12