The uselessness of sublingual Vitamin B12?

In the past I criticized the use of sublingual vitamin B12. Now thereis nasal B12 available. A recent article in Gastroenterology showed thatnasal B12 is effective in treatment of B12 deficiency, using a dose of1.5 mg per day.

Patients with Crohn's disease often have involvement of the last partof the small intestine, which is known as the terminal ileum. That partof the intestine is responsible for absorption of vitamin B12. VitaminB12 is a large molecule that will not cross any part of your body unlessit is specifically brought across by a transport system. For B12 this requiresa system that involves a special protein made in the stomach, called intrinsicfactor, and the transport system in the terminal ileum which brings B12into the body when it is bound with intrinsic factor.

What is interesting is that there is a second way to absorb B12 thatdoes not depend on the usual route. This pathway was described years ago,but requires high dose of B12, about one mg per day. I suspect that theB12 given nasally is eventually swallowed and absorbed by the intestinalroute.

Interesting that now B12 is available in these formulations. While truethat one gets away without a shot, the dose is about 300 times what isgiven orally. I imagine that 350 to 475 mg of vitamin B12 a year adds upin cost, and it may indeed be cheaper to just get a yearly shot of 1 mgof B12. Add to that the cost of testing to see if the oral or nasal B12is getting in the system, and I wonder about the cost.

Patients with Crohn's are at risk for B12 deficiency. Blood counts shouldbe done regularly. In the future, as folate is added to the diet, lookingfor large blood cells as a clue to B12 deficiency will no longer work,so B12 levels will need to be every few years or so to detect the developmentof B12 deficiency in patients.

Stephen Holland, M.D.
Section of Clinical Pharmacology
University of Illinois College of Medicine at Peoria

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