I think you're right Jan. and in July 2012 I started taking 5 mg methylcobalamin daily to fortify myself for my travels in August. Then in dec 2012 a test showed my level was 362, not very impressive considering the supplement. I put it down to the severe gut infection I picked up in Pakistan. I was treated with flagyll. Right now my balance and gait are woeful and nerve pain horrendous. I've had three b12 injections but I think fortnightly is not enough. After the third shot the parasthesias are even worse.