Suter P M, Golner B B, Goldin B R, Morrow F D, Russell R M
United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts.
Gastroenterology. 1991 Oct;101(4):1039-45. doi: 10.1016/0016-5085(91)90731-y.
The role of bacteria in the bioavailability of protein-bound vitamin B12 was examined in eight elderly subjects who had atrophic gastritis and in eight normal controls. On separate days and in random order, vitamin B12 absorption tests were performed using either radiolabeled crystalline or protein-bound vitamin B12. At the same time, bacterial samples were collected from the upper gastrointestinal tract. The tests and gastrointestinal aspirates were performed before and during tetracycline therapy. Crystalline vitamin B12 was absorbed to the same extent in the two study groups. Atrophic gastritis subjects absorbed significantly less protein-bound vitamin B12 than normal controls (mean +/- SEM, 0.7% +/- 0.2% vs. 1.9% +/- 0.5%, respectively). However, protein-bound vitamin B12 absorption in these subjects normalized after antibiotic therapy. These results suggest that the small amounts of vitamin B12 released from the protein binders is readily absorbed (as shown in vitro) and/or metabolized by bacteria.
在8名患有萎缩性胃炎的老年受试者和8名正常对照者中，研究了细菌在蛋白质结合型维生素B12生物利用度中的作用。在不同日期并按随机顺序，使用放射性标记的结晶型或蛋白质结合型维生素B12进行维生素B12吸收试验。同时，从上消化道采集细菌样本。在四环素治疗前和治疗期间进行试验及胃肠道抽吸。两个研究组中结晶型维生素B12的吸收程度相同。萎缩性胃炎受试者吸收的蛋白质结合型维生素B12明显少于正常对照者（分别为平均±标准误，0.7%±0.2% 对1.9%±0.5%）。然而，这些受试者在抗生素治疗后蛋白质结合型维生素B12的吸收恢复正常。这些结果表明，从蛋白质结合物中释放的少量维生素B12易于被吸收（如体外所示）和/或被细菌代谢。
