Carotenoids and Health Laboratory, Jean Mayer USDA Human Nutrition Research on Aging, Tufts University, Boston, MA, USA.
Int J Vitam Nutr Res. 2014;84 Suppl 1:25-9. doi: 10.1024/0300-9831/a000183.
Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.
人类需要维生素 A，可通过摄入富含类胡萝卜素的植物性食物并在体内转化为维生素 A，或者直接从动物性食物中摄取已形成的维生素 A 来获得。因此，准确测定富含类胡萝卜素的植物性食物中的维生素 A 含量非常重要，但也极具挑战。本文旨在综述 80 多年来在发现β-胡萝卜素可转化为维生素 A 之后，为测定植物性维生素 A 原（主要是β-胡萝卜素）的维生素 A 含量而发展起来的各种技术，包括稳定同位素技术，其中包括应用放射性β-胡萝卜素和维生素 A、用维生素 A 和β-胡萝卜素进行耗竭-补充、以及在进食富含β-胡萝卜素的饮食后测量餐后乳糜微粒分数，到使用稳定同位素作为示踪剂来跟踪人体对植物性食物维生素 A 原类胡萝卜素（主要是β-胡萝卜素）的吸收和转化。这些方法大大促进了我们对β-胡萝卜素转化为维生素 A 的吸收和转化的理解。稳定同位素标记的植物性食物可用于确定特定食物中维生素 A 原类胡萝卜素的总体生物利用率。从当地获取的植物性食物可以提供维生素 A，预防全世界仍然存在的维生素 A 缺乏症。
