Watson W S, Vallance B D, Muir M M, Hume R
Scott Med J. 1982 Jul;27(3):240-3. doi: 10.1177/003693308202700309.
Radiotracer B12 analogues, hydroxy- and cyano-cobalamin have been used to study the effects of megadose L-ascorbic acid (vitamin C) ingestion on vitamin B12 metabolism in man. By employing whole body counter techniques it has been shown that, while ascorbic acid can partially inactivate both the important dietary analogue, hydroxycobalamin, and the gastric secretion, intrinsic factor which is essential for B12 absorption, the rapid binding of the B12 analogue to intrinsic factor protects the hydroxycobalamin from attack. As a result, the absorption of hydroxcobalamin is unaffected by the simultaneous ingestion of 1 g ascorbic acid. The absorption of cyanocobalamin, the most stable analogue but not found in quantity in the diet, is slightly increased by ascorbic acid. Whole body retention studies on normal subjects ingesting 2 g ascorbic acid per day show no significant evidence of in vivo destruction of body B12 stores.
放射性示踪剂维生素B12类似物、羟基钴胺素和氰钴胺素已被用于研究大剂量摄入L-抗坏血酸（维生素C）对人体维生素B12代谢的影响。通过采用全身计数技术已表明，虽然抗坏血酸能使重要的膳食类似物羟基钴胺素以及对维生素B12吸收至关重要的胃分泌物内因子部分失活，但维生素B12类似物与内因子的快速结合可保护羟基钴胺素免受攻击。因此，同时摄入1克抗坏血酸不会影响羟基钴胺素的吸收。氰钴胺素是最稳定的类似物，但在饮食中含量不多，抗坏血酸会使其吸收略有增加。对每天摄入2克抗坏血酸的正常受试者进行的全身潴留研究表明，没有明显证据表明体内的维生素B12储备会被破坏。
