Hi all I have just had bloods done and have a b12 level of 251 whilst this is in the very wide bracket, this is at the very bottom end. Is there an optimum b12 level to be at aged 45 and overweight as I am so tired all the time. Thyroid came back normal. White blood cells slightly high, cholesterol too high at 5 so need to loose the weight but am permanently exhausted. Any other things to look for that could help with fatigue?