Posted by Larry Hoover on November 27, 2003, at 9:49:57
In reply to If B12 is stored, why the mega-dosing? (nm) » Larry Hoover, posted by DSCH on November 25, 2003, at 22:41:14
Mega-dosing wouldn't be a permanent strategy, but is instead intended to saturate the various tissues requiring the cobalamin complex.
B-12 shouldn't be called a B vitamin at all. It's a historical error, but retained by convenience, to avoid compounding the confusion. Chemists are a confused lot. ;-)
B-12 is a cobalt ion already bound to a porphyrin complex, something like iron in hemoglobin. It's a big molecule, and it requires a very special process to be brought across the membranes of the intestine (active transport). It was believed that if the active transport process was flawed (pernicious anemia is the result), that the only way around that was injection.
Like many "well known facts", the assumption that B-12 uptake requires active transport is wrong. A small percentage simply diffuses across the intestinal membranes.....maybe 1-3% of the total dose.
So, if you're taking 1 mg of oral B-12, and your active transport uptake is not working (acid reduction therapy for stomach complaints blocks this process), then passive diffusion would supply something like 10-30 micrograms of B-12.
Sublingual tablets are designed to dissolve in the mouth, permitting diffusion across oral membranes. Any that is swallowed gets a second chance in the gut.
If you were severely depleted in B-12 (if symptoms are evident, you are severely depleted), it takes months to get the levels back up.
Lar
poster:Larry Hoover
thread:283013
URL: http://www.dr-bob.org/babble/alter/20031122/msgs/284420.html