中文摘要：

目的确定菠菜及纯品油胶囊中β-胡萝卜素在学龄儿童体内的转化效率。方法选取某农村小学7～9岁儿童32名,随机分为2组,每组16名,维生素A正常和缺乏者各8名,前7天每天午饭及晚饭两组分别补充氘标记菠菜5g（含2H10-β-胡萝卜素230μg）及纯品β-胡萝卜素油胶囊（含2H8-β-胡萝卜素200μg）,早饭两组均服用13C10醋酸视黄醇100μg。在实验的第3、7、8、22及28天分别采集静脉血3ml,用HPLC及GC-MS测定血清中的视黄醇浓度及标记同位素的丰度,计算菠菜及纯品油胶囊中β-胡萝卜素的转化效率。结果β-胡萝卜素油胶囊组维生素A正常和边缘缺乏的儿童β-胡萝卜素的转化率分别为2.9∶1和3.2∶1（质量比）;菠菜组分别为10.1∶1和10.3∶1。结论纯品油胶囊中β-胡萝卜素的转化效率明显高于菠菜;不同维生素A营养状况的儿童β-胡萝卜素的转化效率无明显差异。

英文摘要：

Objective To determine the bioefficacy of pure β-carotene and β-carotene from spinach to vitamin A in schoolchildren of different vitamin A status. Methods Thirty two schoolchildren aged 7-9 years old were selected and then divided into two groups randomly. Each group included 16 subjects, of which the vitamin A level of 8 subjects was normal, the other 8 subjects suffered from vitamin A deficiency. In the first 7 days, one group was given 5 gram spinach （containing 230μg 2 H10-β-carotene） before lunch and dinner and the other group was given pure β-carotene capsule （containing 200μg p-carotene）. Before breakfast, both groups were given 100μg ^13C10 retinal acetate capsule. Blood was drawn on the 3,7,8,22 and 28 day. HPLC and GC-MS were used to determine the retinol concentration and enrichment of isotope and then calculate the bioefficacy of pure β-carotene and β-carotene from spinach to vitamin A. Results The conversion factors of pure β-carotene to vitamin A in oil capsule were： 2.9：1 for the children with normal vitamin A status, 3.2：1 for those suffering from marginal vitamin A deficiency. The conversion factors of spinach p-carotene to vitamin A were 10.1 ： 1 and 10.3 ： 1 for the children with normal and low vitamin A status, respectively. Conclusion The vitamin A conversion bioefficacy of pure β-carotene from oil capsule is much higher than that of spinach. There is no difference of β- carotene bioefficacy to vitamin A for children with different vitamin A status.