B-12 Deficiency- How common is it? Why is it missed?

MeatPileB-12 deficiency, sadly, is usually unrecognized by doctors and every one of us. For a child, this could result in developmental delays, speech challenges, loss of IQ, poor focus, autism, depression, anxiety, seizures, low tone or visual problems. For the adults, add to the list confusion and dementia, strokes and heart attacks, cancer, fertility troubles, leg numbness and tingling or abnormal sensations, balance issues, sleep problems, irritability, personality changes, weakness, and symptoms mimicking Parkinson’s and Multiple Sclerosis. Since most cases of B-12 deficiency are the result of poor absorption rather than inadequate dietary intake, it’s no wonder it is not on the radar for doctors.  

The process of getting B-12 from the food you eat (shellfish, fish, meat, eggs, dairy) into your blood stream in a usable form is a complex journey. The first critical step involves having enough hydrochloric acid from the stomach.  This can be impaired if you have stomach issues (autoimmune destruction of intrinsic factor,  as in pernicious anemia) or atrophy for other reasons such as by-pass surgery. For so many who take acid blocking medicines or antacids, this treatment for stomach ulcers, peptic ulcers (PUD), or reflux (Gastroesophageal Reflux), blocks the acid and will reduce the process of unbinding B-12 from the animal protein.  The enzyme pepsin, from the small intestine, with the acid helps to free B-12 from the animal protein. R-binder proteins carry the B-12 in the intestine where intrinsic factor (that also came from the stomach) latches onto the B-12 to carry it to the ileum where receptors can bind the B-12 and get it into the blood stream.  In the blood stream another protein, transcobalamin II carries the B-12 to all the cells of the body and to the liver for storage.

The other reason doctors rarely think of B-12 deficiency is that we are trained in medical school that this is rare, and presents with megaloblastic anemia (unusually large red blood cells), which often is not the case. Another reason this deficiency is missed has to do with our lab results and what is considered “normal”.  

Many deficient people have “normal” serum B-12 levels.  This is due to the arbitrary designation of normal that likely is based on a population that is itself deficient in B-12.  Most labs will list B-12 deficiency at levels below 180-200 pg/ml and borderline at 200-450 pg/ml.  Normal might be listed from as low as 180 to over 1000 pg/ml. The authors of the book “Could it be B-12” write that serum B-12 should be greater than 550 pg/ml and that for brain and prevention of disease levels should be maintained near or above 1000 pg/ml.

Judy McBride writes (http://www.ars.usda.gov/is/pr/2000/000802.htm) that 39% were found to be in the low normal range, and 16% had levels below 185. She acknowledges that people are having symptoms who are in the low normal range. In 2009, the CDC reported B-12 deficiency found in 1 out of every 31 people over the age of 50 with levels below 200pg/ml. 50% of vegetarians and 80% of vegans show evidence of B-12 deficiency.  

Given the magnitude of illness and disability that is possible with B-12 deficiency, this is one situation where doctors would be wise to treat the patients’ symptoms and not rely on a “normal” lab result on a serum B-12 blood test. I suspect it would be prudent that all of us keep our B-12 levels above 550 pg/ml and aim to be near 1000 pg/ml.  I also use a test by Spectracell that measures the relative amount of B-12 inside the white blood cells, as a way to get an idea of how much is actually available at the cellular level. B-12 is one of those vitamins I feel we all should supplement and add folate to that while you are at it, as the two work together in the key methylation cycle reaction that takes homocysteine to methionine.  If you are suffering from symptoms that might be related to B-12 deficiency, then I recommend you get your levels tested and find a physician who can order Methyl B-12 injections. 


Dr. Paul



  • As a newly pregnant mama, I’ve been way more aware of vitamins than I’ve ever been before. I was focusing a lot on folate (through my diet, and supplements), but no one has really mentioned B-12 (I’m a vegetarian, so I can’t get it through meat) … Thank you for this post … I will be looking into veggie friendly options.

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