This article is about two claims that I’ve discussed previously in this newsletter. Both are seen frequently in the ostomy literature but aren’t true as stated, so can be considered “myths.” And in both cases, the realities are more complicated.
1) The claim that stomas have no nerve endings:
This myth has been stated an awful lot, often by people who should know better, such as ostomy nurses. There is, to be sure, a factual basis behind this myth, namely, the observation that stomas are insensitive to certain painful stimuli such as cutting. This can be a genuine problem, as you can cut your stoma without being aware of it. However, it’s a mistake to jump from this fact to the assumption that stomas have no sensation at all, or that they don’t even have any nerves.
The intestine from which a stoma is made actually has a rich supply of both autonomic and sensory nerves. The autonomic nerves are responsible for certain reflex motions such as peristalsis—the wavelike movements that propel food through the intestine (and if you watch your stoma, you may see it change shape, showing that peristalsis continues to occur in this portion of intestine, illustrating its autonomic nerve activity). The sensory nerves are sensitive to certain kinds of pain, notably when the intestine is stretched. This can be evident when portions of intestine get distended, resulting in cramping sensations which are sometimes very painful. And even after the intestine is made into a stoma, you’ll probably still be able to feel motions that involve stretching of this intestinal tissue.
There is, of course, a possibility that nerves supplying this portion of intestine might have been damaged in the surgery that creates the stoma. But this is unlikely. The intestine’s nerve supply, as well as its blood and lymph supply, are provided through the mesentery, which is a membrane that connects the intestine to the abdominal wall. In making a stoma, surgeons must be careful to preserve connection to the mesentery because of its essential role in providing the intestine’s blood supply (Without a good blood supply, you’ll have just a dead piece of intestine). And, assuming that the intestine’s connection to the mesentery is well preserved, its nerve supply should be preserved as well.
You can read previous articles that I’ve posted about stomas and their nerves at www.ostomyok.org/newsletter/news1510a.shtml
2) The hype about “sublingual” vitamin B12:
In calling this a myth, I should make it clear that sublingual vitamin B12 does work in delivering useful amounts of the vitamin. But it doesn’t really deliver the vitamin sublingually (at least, not to any significant extent), so you needn’t follow the instructions to hold it under your tongue. And other oral forms of vitamin B12 can be equally effective (although the “time release” versions should be avoided, especially by ileostomates).
Vitamin B12 is necessary for many metabolic processes including development of red blood cells, and also maintains normal functioning of the nervous system. Under normal conditions, it’s absorbed in only a small section of the terminal small intestine (ileum), raising the possibility of B12 deficiency if that section of ileum has been removed surgically or damaged by disease. People who may have lost that portion of ileum include some ileostomates, people who’ve had a failed J-pouch or Kock pouch, and some people with urinary diversions (especially continent urinary diversions) made using the terminal ileum. A condition such as Crohn’s disease may have damaged the terminal ileum, even if it hasn’t been removed surgically.
Until fairly recently, it was believed that vitamin B12 taken orally provides no benefit for people who lack the normal absorption mechanism involving the terminal ileum, so these people require B12 injections. Then it was discovered that, in addition to the normal absorption mechanism involving the terminal ileum, a small fraction of B12 taken orally (typically about 1%) gets absorbed by passive diffusion, and this happens along the entire intestine.
This observation provides the basis for safe and effective oral treatment of B12 deficiency, although it requires pretty large doses. The current US recommended daily value for vitamin B12 is only 6 micrograms (and if you check the amounts in multivitamin tablets or B12-fortified foods, you’ll see that they’re at most a few times this value). However, if you absorb only 1% of an oral dose (because you lack the normal absorption mechanism involving the terminal ileum), you’ll need to take 600 micrograms in order to absorb 6 micrograms. A typical recommended oral dose for treating B12 deficiency is 1000 micrograms per day (and if you have short bowel syndrome, you probably need even more). And although these doses are much greater than the usual recommended daily value, they’re quite safe, as there is no known toxicity to vitamin B12, even in very high doses.
The medical establishment has, by now, agreed that B12 deficiency can be treated effectively with oral supplementation. Meanwhile, the companies that make vitamin supplements have been producing “sublingual” B12 products that supposedly provide the vitamin more effectively by delivering it through membranes under the tongue. However, there has never been any scientific evidence that vitamin B12 can be delivered that way. These products are presumably based on analogy with medications like nitroglycerin, which are known to be effectively administered sublingually. But it’s a poor analogy. Nitroglycerin is a relatively small molecule (molecular weight 227) that passes easily through the pores in sublingual membranes. Vitamin B12 is a much larger molecule (molecular weight about 1357) which doesn’t pass through those membranes so easily.
The instructions for “sublingual” B12 say to hold the tablets under your tongue and let them dissolve for a length of time (usually 30 seconds) before swallowing. In reality, at most a negligible amount of the vitamin gets absorbed through sublingual membranes. Then, after you swallow the dissolved tablets, they’re absorbed lower in your digestive tract, as with any other oral formulation. Thus, the sublingual formulation “works,” but not any better than other oral formulations of the vitamin.
Several studies have compared the effectiveness of “sublingual” and regular oral forms of vitamin B12. One study published in 2003 compared the effectiveness of a 500-microgram dose, administered in either a sublingual or regular oral form, in treating B12 deficiency. The result: both were equally effective. Another study published in 2006 did a randomized, double-blind comparison for a vitamin B-complex preparation (including 1000 micrograms of B12), administered in either sublingual or regular oral form. Again, both forms were equally effective.
The conclusion so far is that “sublingual” B12 is a marketing gimmick. The effectiveness of oral B12 depends only on its dosage, so you should just buy the lowest cost version available at the desired dosage. Unfortunately, there’s another complication. An awful lot of the B12 tablets sold in sizes of 1000 micrograms or more are “time release” versions. These should definitely be avoided, especially by ileostomates and anybody else with a shortened digestive tract, as they may pass through your whole digestive tract before releasing an adequate amount of the vitamin. Even for people with a normal-length digestive tract, “time release” B12 is a bad idea. Considering the small fraction of vitamin B12 that gets absorbed (in people who lack the normal mechanism for B12 absorption), delaying that absorption further makes no sense.
Thus, “time release” B12 should be avoided. You’ll want a version that releases the vitamin fairly rapidly, although not necessarily as rapidly as the “sublingual” versions that dissolve in the mouth. “Softgels” are a good alternative that dissolve soon after you swallow them. Sometimes, assuming that a brand of B12 tablets isn’t marked as time release or extended release, it may still be unclear how rapidly it dissolves. In that case you can try it but, if you have an ileostomy, watch to make sure the tablets don’t come through whole into your pouch. If your only choices are between “sublingual” and “time release” formulations, choose the “sublingual” version, but you can ignore the instructions to hold the tablets under your tongue; instead, swallow them directly as with any other tablets.
Finally, if you think you may be vitamin B12 deficient, or have any doubt whether you are doing an adequate job supplementing your B12 level, you can ask your doctor to check your serum (blood) B12 level. This test can be added easily to routine blood testing.
You can read previous articles I’ve posted about vitamin B12 at www.ostomyok.org/newsletter/news0809a.shtml and at www.ostomyok.org/newsletter/news0906a.shtml
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