Medicines that reduce stomach acid help many people with reflux and other digestive conditions.
Because stomach acid helps release B12 from food, long-term use of these medications may contribute to lower absorption in some people.
If one of these medications is on your prescription list, do not stop taking it.
Instead, let your doctor know, as it may be one factor considered when deciding whether testing is appropriate.
Long-Term Metformin
Metformin is a widely used medication for type 2 diabetes.
Over time, it can reduce vitamin B12 absorption in some people.
Again, this is not a reason to stop the medication.
It is simply another reason to ask your doctor whether checking your B12 level makes sense.
Previous Stomach or Bowel Surgery
Some types of surgery involving the stomach or intestines can affect how vitamin B12 is absorbed.
Years may pass before this becomes relevant.
If you have ever had surgery involving your digestive system, mention it when discussing your medical history.
Heavy Alcohol Use
Heavy alcohol use can interfere with nutrition and the body’s ability to absorb important vitamins, including B12.
This is one of several reasons it may contribute to deficiency.
Diets Low in Animal Foods
Vitamin B12 is found naturally in animal-derived foods.
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People whose diets contain very little or none of these foods may have a higher chance of becoming deficient over time.
Diet is only one piece of the puzzle.
Many people with low B12 eat animal foods regularly.
Likewise, many people following carefully planned diets never develop deficiency.
That is why testing matters more than guessing.
A Cause Called Pernicious Anemia
Sometimes the problem is not food.
It is not age.
It is not medication.
Instead, the immune system mistakenly attacks the helper protein needed to absorb vitamin B12.
This condition is called pernicious anemia.
Without enough intrinsic factor, vitamin B12 cannot be absorbed normally through the digestive system.
This is an important reason doctors try to identify the cause of deficiency rather than simply assuming every case is the same.
The underlying reason matters.
Finding the cause helps guide the most appropriate treatment plan.
