维生素A联合其他微量营养素干预对铁代谢稳态的影响

目的 观察维生素A、维生素A+铁和7+1多种微量营养素联合补充对学龄前儿童铁代谢稳态的影响.方法 研究为随机、互相对照、盲法现场干预试验.采用分层与整群抽样相结合的方法从该地区随机选取3所幼儿园全部226名2～7岁学龄前儿童纳入计划干预对象,分别补充100％ RNI的维生素A、维生素A+铁和“7+1”维生素A、铁、维生素B1、核黄素、叶酸、尼克酸、锌和钙.干预前后分别采用氰化高铁法测定全血中血红蛋白含量,反相高效液相色谱法( HPLC)测定血清视黄醇浓度,酶联免疫定量检测法测定血清铁蛋白(serum ferritin,SF),微粒子增强透射免疫法检测可溶性转铁蛋白受体(soluble transferrin receptor,sTfR),并计算sTfR-SF指数(TFR-F指数)及机体总铁含量;同时利用问卷方式调查这些儿童的人口学资料、社会经济状况以及饮食习惯等.结果 完成干预试验儿童共有226名,平均年龄(均数±标准差)为(4.0±0.85)岁.贫血发生率为23.5％,储铁不足发生率为15.0％,维生素A缺乏以及边缘型维生素A缺乏发生率分别是6.3％和25.9％.干预后6个月各组SF水平均较干预前下降(x2=8.3298,x2=16.1471,x=15.1371,P均＜0.01),而维生素A+铁组和“7+1”多种微量营养素组下降最为明显(x2=16.1471,x2=15.1371,P均＜0.05).干预后各组sTfR水平均出现降低(x2=15.1171,x2=5.2617,x2=4.8844,P均＜0.01),尤以维生素A组最明显(x2 =15.1171,P＜0.05);维生素A组TFR-F指数以及机体总铁含量在干预前后无明显变化(t =0.1817,t=1.7736,P均＞0.05),而维生素A+铁组和“7+1”多种微量营养素组的TFR-F指数明显下降、机体总铁含量明显增加(t=5.3561,t=6.5979,t=11.1663,t =8.7306,P均＜0.05).结论 单独维生素A补充对铁动员和铁利用均有明显影响,但对铁在肠道的吸收作用不明显;维生素A联合铁剂或“7+1”多种微量营养素的补充比单独维生素A可更好地改善学前儿童铁缺乏.

Effects of vitamin A, vitamin A plus iron and multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis

Objective To evaluate the effect of vitamin A,vitamin A plus iron and “7 + 1”multiple micronutrient-fortified seasoning powder on iron metabolic homeostasis in preschool children.Methods This was a randomized,controlled and blinded interventional field trial.A total of 226 2-7 years old preschool children were recruited from three nurseries in the area,and they were randomly assigned into three different fortified diet groups for 6 months.The subjects in Group Ⅰ were fortified with vitamin A;those in Group Ⅱ and Ⅲ were fortified with vitamin A plus iron and vitamin A plus iron,thiamine,riboflavin,folic acid,niacinamide,zinc and calcium (7 + 1 ),respectively.The concentration of serum vitamin A was measured by high-performance liquid chromatography ( HPLC),serum ferritin (SF) was measured by enzyme-linked immunosorbent assay (ELISA),soluble transferrin receptor (sTfR) was measured by microparticle-enhanced,and hemoglobin (HB) by hemiglobincyanide,the sTfR-SF index (TFR-F index) and total body iron content were computed respectively before and after intervention.Simultaneously,children's demographic data,socio-economic status and eating habits,etc.were investigated by questionnaires.Results A total of 226 preschool children were included in the study with age ranged from 2 to 7 years with average age (4.0 ±0.85) (means ± standard deviation).The prevalence of anemia,deficient iron storage,vitamin A deficiency (VAD) and suspect sub-clinical vitamin A deficiency (SSVAD) were 23.5％,15.0％,6.3％ and 25.9％,respectively.The levels of SF and sTfR significantly decreased after intervention in all groups (x2 =8.3298,x2 =16.1471,x2 =15.1371,x2 =15.1171,x2 =5.2617,x2 =4.8844,P ＜0.05 ) especially in group Ⅱ and group Ⅲ for SF ( x2 =16.1471,x2 =15.1371,P＜ 0.05 ) and group Ⅰ for sTfR (x2 =15.1171,P ＜ 0.05 ).No marked change of TFR-F index and total body iron contents was observed in group Ⅰ ( t =0.1817,t =1.7736,P ＞ 0.05 ),while TFR-F index decreased and total body iron contents increased in group Ⅱ and group Ⅲ ( t =5.3561,t =6.5979,t =11.1663,t =8.7306,P ＜0.05) after intervention.Conclusion Vitamin A intervention has significant effect on iron storage and mobilization but seldom effect on iron absorption in small intestine.The combination of vitamin A and other micronutrients might be a better intervention for the improvement of iron deficiency for preschool-children.