My B12 levels were higher...I believe around 500, and I was very tired and had other issues. I thought my Dr. was being overly cautious when he wanted me to take additional B12. He insisted, and I took it. I take a B50 tablet (has all the B's in it) and additional B12 on top of that in a separate tablet. I take the B12 that starts with the letters "methyl..." because this one is said to work the most efficiently. I agree, go to the vitamin board here at NeuroTalk to get additional and very good information. BTW, too much B12 will not hurt you. It can ONLY help and VERY likely this WILL be the case.