A decrease in vit.
B12 level could be because of poor intake of vit. B12 rich foods (meat, egg, fish or poultry ) or a problem with the absorption of vit b12 because of problems with the stomach production of intrinsic factor or the small intestine(ileum).
Whatever maybe the cause it will be important to find out, if the deficiency of vitamin is leading to any symptoms, most common are anemia, nerve problems like parasthesia and numbness of hands and legs.
And you did not mention about any intestinal surgeries if you have had before because that can also be the cause for the problem
Next Steps
Blood test: CBP
TREATMENT: INJ. OPTINURON 1ampoule intramuscular once a day for 5 days
followed by tab. methycobal once a day for 1 month
Health Tips
take vit
b12 rich foods meat, eggs, poultry, fish or else vitb12 fortified foods