Rich G T, Fillery-Travis A, Parker M L
Institute of Food Research, Norwich Research Park, Norwich, United Kingdom.
Lipids. 1998 Oct;33(10):985-92. doi: 10.1007/s11745-998-0296-5.
A current model for carotenoid transport and absorption in the gut proposes an initial solubilization in the oil phase of dietary emulsions followed by incorporation of the carotenoids in mixed bile salt micelles. To assess the relevance of the first stage of this model to what is observed in vivo we have examined the transfer of carotene from carrot juice to olive oil. Increased acidity enhanced the transfer from both whole juice and carotene crystals isolated from carrot chromoplasts. The transfer was significantly slower from whole juice. By using exogenous beta-carotene and measuring its transfer to oil in the presence and absence of carrot juice we have demonstrated that the inhibition of the transfer in juice arises, at least in part, from soluble juice factors. The inhibition is relieved by a fall in pH, which leads to lowering of the electric potential at the oil/aqueous phase interface and aggregation of carrot tissue including crystalline carotene. Under conditions of low pH, oil droplets adhere to the tissue aggregates, allowing carotene to pass into the oil. Our results provide an explanation for why carotene absorption in vivo is depressed by conditions of low gastric acidity.
目前关于类胡萝卜素在肠道中运输和吸收的模型提出，其首先在膳食乳液的油相中溶解，随后类胡萝卜素被纳入混合胆盐微团中。为了评估该模型的第一阶段与体内观察结果的相关性，我们研究了胡萝卜素从胡萝卜汁向橄榄油的转移。酸度增加会增强从全汁以及从胡萝卜质体中分离出的胡萝卜素晶体的转移。从全汁中的转移明显较慢。通过使用外源性β-胡萝卜素并测量其在有无胡萝卜汁存在下向油中的转移，我们证明了汁中转移的抑制至少部分源于可溶性汁因子。pH值下降可缓解这种抑制，这会导致油/水相界面处的电势降低以及包括结晶胡萝卜素在内的胡萝卜组织聚集。在低pH条件下，油滴附着在组织聚集体上，使胡萝卜素能够进入油中。我们的结果解释了为什么低胃酸条件会降低体内胡萝卜素的吸收。
