What are the ingredients in Active B12 5000 sourced from? Education Team April 11, 2022 20:08 Updated Follow Ingredient Source Vitamin B12 (as methylcobalamin and adenosylcobalamin) Synthetic Related articles Are there any warnings or side effects when using Active B12 5000? What is the purpose of each ingredient in Active B12 5000? What are the ingredients in Optimal Prenatal sourced from? Comments 0 comments Article is closed for comments.