Bioavailability of Vitamin B12
Bioavailability of Vitamin B12
复制标题
DOI：
10.1024/0300-9831/a000041
复制
发表时间：
2010-10-01
影响因子：
2.3
通讯作者：
Allen, Lindsay Helen
中科院分区：
文献类型：
--
作者：
Allen, Lindsay Helen
维生素B12缺乏症在所有年龄段的人中都很常见，他们摄入的动物源性食物很少，包括发展中国家的人口。它在老年人中也很普遍，即使在较富裕的国家，由于他们从食物中吸收B12不良。几种方法已被应用于诊断维生素B12吸收不良，包括席林试验，现在很少使用，但这些方法不能量化生物利用度。大多数关于食物中B12生物利用度的信息都是在40到50年前收集的，当时使用钴的放射性同位素来标记类可啉环。数据稀少，动物组织体内标记所需的放射性水平可能过高。正在开发的一种新方法使用低剂量的放射性作为C-14标记的B12，通过加速器质谱法测量尿液和粪便中排泄的同位素。这项测试表明，未被吸收的维生素在肠道中被降解。由于活性吸收过程的饱和，即使在通常的食物摄入量范围内，生物利用度百分比也与消耗的剂量成反比。这对于评估和解释生物利用度值、设定膳食需求以及解释维生素摄入量和状态之间的关系具有重要意义。
Vitamin B12 deficiency is common in people of all ages who consume a low intake of animal-source foods, including populations in developing countries. It is also prevalent among the elderly, even in wealthier countries, due to their malabsorption of B12 from food. Several methods have been applied to diagnose vitamin B12 malabsorption, including Schilling's test, which is now used rarely, but these do not quantify percent bioavailability. Most of the information on B12 bioavailability from foods was collected 40 to 50 years ago, using radioactive isotopes of cobalt to label the corrinoid ring. The data are sparse, and the level of radioactivity required for in vivo labeling of animal tissues can be prohibitive. A newer method under development uses a low dose of radioactivity as C-14-labeled B12, with measurement of the isotope excreted in urine and feces by accelerator mass spectrometry. This test has revealed that the unabsorbed vitamin is degraded in the intestine. The percent bioavailability is inversely proportional to the dose consumed due to saturation of the active absorption process, even within the range of usual intake from foods. This has important implications for the assessment and interpretation of bioavailability values, setting dietary requirements, and interpreting relationships between intake and status of the vitamin.