I am a long distance runner looking to add some supplements. I have looked at EPO but have found no way to obtain it and it is very pricey. In endurance, RBC are important and I have read that B-12 boosts their production. Some say it does absolutely nothing while others claim it works. What is the overall consensus on B-12 and will it help me have more energy/be able to train longer and harder. Is it like a very weak and short term EPO boost? Does B-12 last hours, days, or weeks? Thanks for answering any questions and PM me if you don't want to post in regard to B-12 or EPO.