Unfortunately, simply eating plenty of vitamin B12-rich foods is not always the answer since many people have problems with vitamin B12 absorption.
Here’s why …
Vitamin B12 occurs in animal foods bound to protein and gets released when hydrochloric acid and gastric protease in the stomach break this bond.
But many factors can inhibit this process.
The first is age.
An estimated 10-30% of adults over the age of 50 have difficulty absorbing vitamin B12 from food.
Thus, it’s recommended that all adults past this age take supplemental B12.
Eating disorders and chronic digestive disorders also make it difficult to absorb vitamin B12 from food.
There are several classes of medications that interfere with vitamin B12 absorption.
Proton pump inhibitors (PPIs) like Nexium, Prevacid and Prilosec and histamine-2 receptor antagonists (H2RAs) like Pepcid, Tagamet and Zantac are popular for acid indigestion, acid reflux, GERD, heartburn, and ulcers.
These drugs are strongly linked to vitamin B12 deficiency since users of these medications lack adequate stomach acid to break down and absorb vitamin B12.
Metformin is a very popular drug for treating type 2 diabetes.
Forty percent of patients using metformin have a vitamin B12 deficiency or are in the low-normal range.
Seventy-seven percent of metformin users develop peripheral neuropathy, a common form of nerve damage associated with type 2 diabetes.
Other medications that affect B12 levels include anti-seizure medications and chemotherapy drugs.
Lack of Intrinsic Factor
In a very small portion of the population, vitamin B12 deficiency is caused by a lack of intrinsic factor, a protein secreted by the stomach lining that binds to vitamin B12 and enables its absorption.
Lack of intrinsic factor can be caused by weakened stomach lining or certain autoimmune diseases.
This can lead to pernicious anemia, a decrease in red blood cells that occurs when the intestines cannot properly absorb vitamin B12.
If left untreated, it ultimately leads to serious neurological damage.
Treatment usually involves mega-doses of oral B12 or regular B12 injections.