Absorption of Vitamin B12 in a Rectal Suppository

Intestinal Mucosa and Vitamin B₁₂ Absorption

“…The inability of the large bowel to absorb orally administered B,2 [2,24] or locally instilled physiological doses of Bi2 [74] has been amply shown, although under artificial conditions and with massive doses of B12, some absorption may be detected [8,56], Radio B12 given in a rectal suppository is also absorbed from the distal colon [75]; such absorption has been thought to be effected by a physical mechanism, such as diffusion [24,39], However, B12 synthesized by intestinal flora in the colon is not absorbed, probably due to ineffective concentrations of free B12 [24], Sorbitol has been shown to in crease absorption of B12 for unexplained reasons [24,32], and magnesium sulfate has a similar effect [69]. Recently, Goto [26] from our laboratory showed that B12 had escaped absorption in the small bowel regurgitated from the cecum back into the ileum under the influences of these cathartics.…”