哺乳期农村乳母乳汁无机元素含量的变化

目的了解哺乳期人乳无机元素含量的变化及其与乳母膳食的关联。方法采用横断面调查方法,收集55名陕西省澄城县农村健康乳母清晨乳样,利用原子吸收分光光度法测定乳汁钙、镁、铁、锰、锌和铜的浓度。采用24小时回顾法进行连续3天膳食调查,计算膳食营养素的摄入量。结果农村乳母乳汁中镁、锌、铜浓度随哺乳期延长明显降低,铁浓度随哺乳期延长而上升。乳母膳食钙摄入量约为钙膳食参考摄入量(DRI)1/3,膳食无机元素的摄入量与人乳相应元素之间无明显相关性。多因素分析表明,乳汁中钙与镁、铁与铜、锰与锌均呈正相关,钙分别与乳脂、铁、锌呈负相关。结论随哺乳期时间延长,成熟乳中镁、锌、铜浓度降低而铁浓度增加,乳母膳食钙的摄入严重不足,乳汁各元素与膳食相应元素之间无关联。

Changes of Inorganic Elements of Breast Milk in Rural Lactating Women

Objective To study changes of inorganic elements of breast milk in rural lactating women and to explore the relationship between inorganic elements of breast milk and maternal mineral intakes. Methods A cross-sectional study was performed to investigate 55 rural women in Chengcheng County, Shaanxi Province. Milk samples were collected early in the morning. The concentrations of calcium, magnesium, iron, manganese, zinc, and copper in milk were measured by atomic absorption spectrophotometry. Maternal nutrient intakes were collected from 24-hour dietary recalls on 3 consecutive days. Results The levels of magnesium, zinc, and copper significantly decreased during the lactation period, while the level of iron increased. Calcium intake of rural lactating women was less than one third of calcium dietary reference intakes(DRIs). No correlation was found between mineral intake and breast milk composition. As shown by multiple factors analysis, three pairs of elements of breast milk were positively correlated: calcium and magnesium, iron and copper, and manganese and zinc; however, the level of calcium was negatively correlated with that of lipid, iron, and zinc. Conclusions In human milk, the concentrations of magnesium, zinc, and copper decrease and iron concentration increases during the lactation period. Low calcium intake is a severe problem in rural lactating women. The concentrations of calcium, magnesium, iron, manganese, zinc, and copper are not associated with maternal mineral intakes.