(The search feature is unreliable, but this space is free so I won't complain.) Patients must learn about B12: It can become low regardless of diet.  

A surprising percentage of physicians still believe information that was debunked by accepted research decades ago. Missed or delayed diagnosis and/or treatment can result in slowly or rapidly developing disability, and death.

Most doctors still think that all B12-deficient people are anemic and show a very low B12 test result. Most also have serious misconceptions about symptoms.


(Sorry about the formatting. It changed on its own and makes no sense to me. Some sections are not cooperating with repair efforts.)

Unfortunately, many editors of medical reference materials have not updated their B12 information for many years to decades. Thus, even a doctor who cares enough to check will likely be misled or worse.


Myths that persist in spite of decades of accepted research to the contrary:

Myth:  B12 deficient people are anemic.

Fact:   Many years have passed since this was shown to be wrong in a large percentage of cases. Many people who are severely B12 deficient and incurring serious damage to their central nervous systems are not anemic. In fact, a person can be near death due to B12 deficiency and still have normal CBC and MCV. Doctors and medical writers who believe that absence of anemia rules out B12 deficiency are decades out of date.


Goldman: Cecil Textbook of Medicine, 22nd ed., page 1056

"Several clinical studies document that a normal hematocrit and/or mean cell volume occur in at least 25 to 50% of patients whose neuropsychiatric abnormalities are caused by cobalamin deficiency and respond partially or completely to cobalamin therapy."


Myth:  Pernicious anemia is a type of anemia caused by B12 deficiency.

Fact:   That is 19th-century and early 20th-century thinking. "Pernicious anemia" is not an anemia (or anaemia). "Pernicious anemia" is failure of a stomach lining to secrete intrinsic factor, and that is the most common cause of severe B12 malabsorption. 

Pernicious anemia was named as 19th-century doctors watched helplessly while a mysterious disease caused people to develop a type of anemia and die.  Medical people then had no way of knowing that the "pernicious" ailment wasn't a type of anemia and that many others who were not anemic were dying as a result of the same cause.


Myth:  A normal B12 test result rules out B12 deficiency.

Fact:   A large percentage of B12 deficient people test within the low end of the "normal" range. And a smaller percentage while deficient test much higher.

The B12 test was shown unreliable many years ago. Even further testing of methylmalonic acid and homocysteine misses some cases, but many more cases are revealed by one or the other of those tests (if not both) showing higher than normal.

Goldman: Cecil Textbook of Medicine

Serum cobalamin [B12] and folate levels therefore cannot be used alone to establish the diagnosis of cobalamin or folate deficiency unequivocally. The problem is compounded by the fact that not all patients with clinically confirmed cobalamin or folate deficiency (defined as those who have objective clinical responses to appropriate therapy) have low values for serum cobalamin or folate.
The following distribution of serum cobalamin levels has been noted in clinically confirmed cobalamin-deficient patients: less than 100 pg/mL, approximately 50%; 100 to 200 pg/mL, approximately 40%; 200 to 350 pg/mL, approximately 10%; and higher than 350 pg/mL, approximately 0.1% to 1%.


Purpose of this website:

This site and the information on it are NOT intended to take the place 0f a physician.

    This is the place to learn about: who might need B12; various reasons a person might need B12; why B12 deficiency is seriously underdiagnosed; things to keep in mind when choosing a B12 vitamin; and more. Unfortunately, once you've read the first page, you will know more about B12 than most doctors. This is not because I'm so smart; it is because a large percentage of medical people are terribly uninformed and misinformed regarding this issue.

    Far too much of the medical literature has not been updated on this subject in many years, some even decades, and researchers have made giant leaps since then. Many medical references directed at the consumer (and promotional materials masquerading as references),  contain blatantly incorrect information.  Some of the worst tell people that bananas, beans, or potatoes are great sources of B12. Ack! This isn't even good old information. B12 is obtained from animal products, foods fortified with B12, and supplements or pharmaceuticals containing B12.

    If a person malabsorbs severely, they probably aren't getting any B12 unless they are taking enough in a supplement or pharmaceutical.   Treatment.

    It is especially distressing that some prestigious and otherwise excellent sources of information provide blatantly bad B12 information.



Causes and associated conditions

Symptoms are too many to list

Citations of medical literature

So-called typical symptoms often not present 


B12 types

B12 is not a cure-all, but...


B12 Overview