Constant low levels of B12

I have for the last year, had trouble keeping my B12 levels up.  It is always in the low normal range, even after B12 shots.  I have had the lowest to be 211 and the highest to be 330 after taking shots every two weeks.  I do not have a reason for this other than, "sometimes people just stop asorbing it".  I am 33 years old and no one in my family has ever had this problem.  Is there anything else that could cause it other than I just can't asorb it anymore? I am so tired all of the time, I forget things very often and I bruise very easily and the bruises stay a long time.  I am also, eating salads at least four times a week and trying to eat more things high in B12.

[Myown]

research "intrinsic factor."

I used to be able to explain this off the top of my head, but I am quite foggy lately due to medication I am on,,,,but if you google, you will find lots of info.

Good luck,
MO

[Evelyn341]

What is the necessity to maintain a normal level in B-12?..