If the individual has COMT or MAO variants expressed, or may need less methyl groups for other reasons, use Pro Hydroxycobalamin. Hydroxocobalamin is a unique form of vitamin B12, which is more readily converted into the coenzyme forms than conventional cyanocobalamin. This allows hydroxocobalamin to serve as an effective broad-spectrum form of vitamin B12.Fom PHP/Nutritional Specialties.