Note: An updated version of this article has been published in our September 2008 newsletter.
I recently became interested in the topic of Vitamin B-12 deficiency and did some research on this subject. This article summarizes what I learned. I believe this reflects current thinking as of November 2005.
Who is at Risk?
Among non-ostomates, a major concern has been a condition called “pernicious anemia”—a disorder involving failure of certain cells in the stomach to produce a substance called “intrinsic factor” which binds with vitamin B-12 before it is ultimately absorbed in the terminal small intestine (ileum). People who avoid foods of animal origin (strict vegans) may lack vitamin B-12 in their diets because this vitamin is normally found only in animal-based foods. Also, there is evidence that people lose ability to absorb vitamin B-12 as they age; consequently some doctors recommend routine B-12 screening for everyone over age 50 (or at least age 65).
Ostomates and people with inflammatory bowel disease may additionally be at risk due to loss or damage to the portion of terminal ileum that absorbs vitamin B-12. If you have an ileostomy or you had a failed J-pouch, a significant length of terminal ileum may have been removed in your surgery. Similarly, if you have a urinary diversion (especially a continent urinary diversion), a portion of ileum may have been removed and used in making your urinary diversion. If you have Crohn’s disease, it may have damaged your terminal ileum.
Your body stores vitamin B-12 in the liver, which normally holds enough to last several years. Therefore, deficiency may not show up until several years after an operation or disease that impairs your ability to absorb the vitamin.
Symptoms of Vitamin B-12 Deficiency
Vitamin B-12 is necessary for development of red blood cells and maintains normal functioning of the nervous system. Deficiency causes anemia (reduced oxygen carrying capacity of the blood resulting in fatigue) and can produce neurological symptoms such as numbness or tingling in the hands and feet and difficulty keeping your balance. Prolonged deficiency can cause irreversible nerve damage. It may also cause psychological problems such as depression, memory loss and dementia.
While anemia is often cited as the primary symptom of vitamin B-12 deficiency, anemia can also be caused by deficiency of folic acid (another B vitamin). This poses a serious danger, in that increasing your folic acid intake may mask a B-12 deficiency. Folic acid can correct the anemia that is caused by vitamin B-12 deficiency but will not correct the nerve damage also caused by B-12 deficiency. Therefore, if you are at risk for vitamin B-12 deficiency, you need to get it checked instead of simply trying to treat the anemia.
Testing for Vitamin B-12 Deficiency
Vitamin B-12 isn’t normally checked in a routine blood count. However, a test for blood level of vitamin B-12 (serum B-12) can be added to a standard blood count easily and inexpensively, so you may wish to request this if you think you may be at risk for B-12 deficiency.
One problem with the serum B-12 test is that a folic acid deficiency can produce an artificially low serum B-12 level. Therefore, it is best to also check the folic acid level while measuring serum B-12.
Another problem with serum B-12 testing is that a result in a certain “low normal” range (from about 100 to 400 picograms per milliliter) can occur in patients who are actually deficient in vitamin B-12. To resolve these cases, levels of two other substances, homocysteine and methylmalonic acid (MMA) should be checked. An elevated level of either of these would then indicate vitamin B-12 deficiency. Unfortunately, the tests for homocysteine and MMA are fairly expensive (around $100 each) and insurance companies may be reluctant to cover them; therefore, you should probably hold off on getting these tests unless the serum B-12 test comes back in the above “low normal” range.
Vitamin B-12 Replacement Therapy
People who avoid animal foods but have normal physiology need a vitamin B-12 supplement but can get by with a preparation containing only the normally recommended daily value, which is 6 µg (micrograms). People with impaired absorption of vitamin B-12 require more aggressive measures and can choose among three ways to take their B-12: by injection, nasally, or orally—where the first two require a prescription while the third is available over the counter. Some more information about each method:
B-12 injections: This method bypasses the normal gastrointestinal process of B-12 absorption by injecting it directly into the bloodstream. In cases of serious B-12 deficiency, this method should always be used first in order to build up the B-12 level as rapidly as possible; then, the patient may switch to one of the other methods if desired. B-12 injections may be self-administered in the same way that diabetic patients can give themselves insulin shots. When administered this way, the injections are quite inexpensive. Maintenance therapy may require only one B-12 injection per month.
Nasal B-12: This method also bypasses the normal gastrointestinal absorption process, as vitamin B-12 is absorbed through the nasal mucous membranes. There are now two forms of nasally applied B-12: a gel preparation which has been available in the United States since 1997 and a true nasal spray which received FDA approval in 2005. Both versions are marketed by the same company, QOL Medical. Because of their monopoly, this company can charge a premium; therefore, this is the most expensive way to take vitamin B-12.
Oral B-12: Until recently, conventional medical opinion held that B-12 taken orally was useless to people who lack the normal gastrointestinal mechanism for absorbing the vitamin. However, recent research indicates that even in such people, when a large oral dose of vitamin B-12 is taken, a small fraction (typically around 1%) does get absorbed. Therefore, if you take about 1000 µg of oral B-12 per day (which is more than 100 times the usually stated daily value and is much greater than the amounts found in food sources or multivitamin preparations), you may absorb enough to be effective. Many drug companies now produce vitamin B-12 tablets in large sizes of 1000 µg or more, and these are available quite inexpensively. The tablets come in two forms: regular tablets and “sublingual” versions intended to be held under the tongue before being swallowed. There isn’t any evidence that sublingual B-12 is absorbed any better than regular B-12 tablets. Unfortunately, it seems that most of the non-sublingual B-12 tablets in sizes of 1000 µg or greater are marked “time release.” Ileostomates are generally advised not to take time release tablets because they may pass out through your stoma before releasing all their medication. If this is a concern, you can either buy the sublingual tablets (although it probably makes no difference whether you follow the instructions to hold them under your tongue!), or you can buy regular non-time-release B-12 tablets, which are often sold in sizes up to 500 µg, and take two of them.
Whichever B-12 supplementation method you use, you don’t need to worry about overdosing. Vitamin B-12 has been found to be safe, even in quantities much larger than any discussed here. The body simply discards what it cannot use.
Links below added 2008-05-11:
Research article abstracts (cited in above Wikipedia article)
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