Because most people store enough B12 to thrive for  years, B12 deficiency can sneak up on one even after malabsorption becomes severe. If malabsorption is not severe, problems may begin and progress much more slowly. It truly is a "pernicious" condition if untreated.

 Stomach atrophy (gastric atrophy):

The most common cause of B12 deficiency is malabsorption due to atrophy of the stomach lining. This causes moderate malabsorption in many many people. Unfortunately, the symptoms (if present) often appear to suggest too much stomach acid, so it is common for people with too little stomach acid to be given acid reducers which worsen the digestive problem. 

People who lack sufficient stomach acid cannot break B12 out of foods. But if the stomach still secretes intrinsic factor, they can absorb supplemental B12 and B12 in fortivied foods.

Atrophy of the stomach lining is frequently a result of autoimmune malfunction, nothing the individual has done or failed to do. However, some things make it even more likely or worsen the condition: certain pharmaceuticals, over-the-counter products, actions or conditions that damage overall health, etc.

With or without acid reducers or any other action, some patients will progress beyond low acid to loss of intrinsic factor, and, as a result, severely malabsorb B12. This condition, lack of intrinsic factor, is properly called "pernicious anemia." In cases on severe malabsorption, either shots or daily oral doses of at least 1000 mcg (not timed release) are necessary to rebuild B12 stores. Pernicious anemia still is often wrongly referred to as an anemia caused by B12 deficiency, and in fact some wrongly call B12 deficiency "pernicious anemia."   See Myths: Home


Gastric (stomach) or ileum surgery:

Bypassing or removing a significant portion of the stomach causes serious malabsorption of B12. 

Imagine how many more cases of deficiency they would have found if they had used different criteria for for determining deficiency. Some being damaged by B12 deficiency do not develop high methylmalonic acid or homocysteine. Some are deficient at higher B12 serum levels than 221 pmol/L.

Available at PubMed PubMed: Elevated methylmalonic acid and total homocysteine levels show high prevalence of vitamin B12 deficiency after gastric surgery.

After reading the article, imagine how many more cases of deficiency they would have found if they had used different criteria for for determining deficiency. Some being damaged by B12 deficiency do not develop high methylmalonic acid or homocysteine, and many are deficient at higher B12 serum levels than 221 pmol/L. 


Parasites or overgrowth of bacteria:

Parasites (notably those acquired when eating raw fish) or an exceptionally large number of bacteria in the digestive system can compete for B12, thus depleting B12 stores over time.

Overgrowth of bacteria can compete with the body for B12 and thus cause deficiency. This is more likely to happen when stomach acid is low, which is an more common cause of malabsorption and deficiency.


Use of Nitrous Oxide:

Nitrous Oxide disables B12. A person who has a good store of B12 and absorbs it normally will not have a problem, but one who is already on the way toward deficiency, does not absorb normally, and is not receiving B12 replacement will be pushed more rapidly to severe deficiency and damage.  In some cases, severe symptoms develop within hours. The sooner good B12 treatment is given, the more likely patient will recover fully.

Recreational Nitrous Oxide use can deplete B12 very slowly, and symptoms can come on so subtly as to be unnoticed until serous damage has been done and may not be repairable.


Celiac (or even more frequently undiagnosed, gluten sensitivity):

One of the conditions that is as unlikely to be diagnosed in a timely manner (if at all) is a gluten sensitivity, which will not be revealed by the usual testing. This link is to an exceptionally good site for both the gluten and B12 issues: The Gluten File


Multiple Sclerosis (MS):

Some researchers are trying to unlock the mysterious relationship between MS and B12.

  • It is very common for people who actually have multiple sclerosis to eventually show B12 deficiency as well.
  • People who do not have MS but are in an advanced state of B12 deficiency can incur damage that mimics MS. That is why B12 deficiency is on the list of conditions that are to be eliminated before an MS diagnosis is made.

Unfortunately, many people are given a provisional diagnosis of MS and told to "wait and see " without having had proper testing for B12 deficiency, B12 treatment, or advice to take sufficient B12. Some of the more knowledgable doctors tell patients with symptoms to take at least 1000 mcg B12 orally each day, just in case. There is no good reason for a person to incur damage because they needed and didn't receive a safe and inexpensive vitamin.




Much more to come...