Heaney R P
Creighton University, Osteoporosis Research Center, Omaha, NE 68131, USA.
J Nutr. 2001 Apr;131(4 Suppl):1344S-8S. doi: 10.1093/jn/131.4.1344S.
For non-metabolizable supplemental nutrients, bioavailability is effectively equivalent to absorbability. Methods for measuring absorbability (balance, pharmacokinetic, tracer, urine increment, evoked physiological responses, and in vitro) are briefly characterized and their utility compared. When intrinsic labeling of a source is possible, tracer methods are generally the most accurate and precise, as well as often the least expensive. Factors influencing the measured end points of the various methods are described briefly. These include source factors such as pharmaceutic formulation, subject factors such as mucosal mass and the need status of the absorbing subject, and co-ingested factors such as other foods or food constituents. Extensive experience has shown that absorbability is difficult to predict from knowledge of the chemistry of the source, or even from the results of in vitro testing. Hence direct measurement of absorbability is essential to assure regulators and the general public that the source delivers what it promises.
对于不可代谢的补充营养素，生物利用度实际上等同于吸收率。简要介绍了测量吸收率的方法（平衡法、药代动力学法、示踪法、尿增量法、诱发生理反应法和体外法），并比较了它们的实用性。当能够对来源进行内源性标记时，示踪法通常是最准确、最精确的，而且往往成本最低。简要描述了影响各种方法测量终点的因素。这些因素包括来源因素，如药物制剂；主体因素，如黏膜质量和吸收主体的需求状态；以及共同摄入的因素，如其他食物或食物成分。丰富的经验表明，仅根据来源的化学知识，甚至根据体外测试结果，都很难预测吸收率。因此，直接测量吸收率对于向监管机构和公众保证该来源能够兑现其承诺至关重要。
