Sánchez López C L, Hernández A, Rodríguez A B, Rivero M, Barriga C, Cubero J
Laboratorio de Crononutrición, Departamento de Fisiología, Facultad de Ciencias, Universidad de Extremadura, Badajoz, España.
Nutr Hosp. 2011 May-Jun;26(3):511-4. doi: 10.1590/S0212-16112011000300012.
Breast milk is changing with the progression of lactation and during a 24-h period. To determine the effect of diurnality or nocturnality on total nitrogen and protein content of the breast milk. We collected human milk samples from health mothers living throughout Community of Extremadura (Spain) from January 2008 to December 2008 with less than two months of lactation. We divided the samples in three groups: calostral group (1-5 days postpartum), transitional group (6-15 days postpartum) and mature group (> 15 days postpartum). All samples were stored in a freezer at -80 ºC. We considered as day period between 08:00-20:00 h and night period 20:00-08:00 h. Analysis of the human milk samples was based on the Kjeldahl method. Protein contents were calculated from total nitrogen x 6,25. The statistical analysis of the data was descriptive (mean ± standard deviation) and inferential (T-Student test). No differences (P > 0,05) were found to exist among the contents of individual human milk samples. The mean contents of each component were as follows: Total nitrogen of calostral, transitional and mature group was 0,30 ± 0,06 g/dL (night period), 0,29 ± 0,05 g/dL (day period); 0,26 ± 0,04 g/dL (night period), 0,25 ± 0,04 g/dL (day period); 0,22 ± 0,05 g/dL (night period), 0,20 ± 0,04 g/dL (day period) respectively, in this mature group with a statistical variation (P < 0,05). Protein content of calostral, transitional and mature group was 1,88 ± 0,4 g/dL (night period), 1,81 ± 0,3 g/dL (day period); 1,62 ± 0,3 g/dL (night period), 1,59 ± 0,3 g/dL (day period); 1,35 ± 0,3 g/dL (night period), 1,26 ± 0,3 g/dL (day period) respectively, in this mature group with a statistical variation (P < 0,05). Although we observed differences in the nitrogen and protein content during the individual stages of lactation, it is just in the population of mature lactating women, where the components analyzed varied significantly between day and night.
母乳会随着哺乳期的推进以及在24小时内发生变化。为了确定昼夜节律对母乳总氮和蛋白质含量的影响。我们从2008年1月至2008年12月收集了来自西班牙埃斯特雷马杜拉社区的健康母亲的母乳样本，这些母亲的哺乳期少于两个月。我们将样本分为三组：初乳组（产后1 - 5天）、过渡乳组（产后6 - 15天）和成熟乳组（产后> 15天）。所有样本都储存在-80ºC的冰箱中。我们将08:00 - 20:00视为白天时段，20:00 - 08:00视为夜间时段。母乳样本的分析基于凯氏定氮法。蛋白质含量通过总氮×6.25计算得出。数据的统计分析包括描述性（均值±标准差）和推断性（t检验）。在个体母乳样本的含量之间未发现差异（P>0.05）。各组分的平均含量如下：初乳组、过渡乳组和成熟乳组的总氮在夜间时段分别为0.30±0.06 g/dL、0.26±0.04 g/dL、0.22±0.05 g/dL，在白天时段分别为0.29±0.05 g/dL、0.25±0.04 g/dL、(0.20±0.04 g/dL，该成熟乳组存在统计学差异（P<0.05）。初乳组、过渡乳组和成熟乳组的蛋白质含量在夜间时段分别为1.88±0.4 g/dL、1.62±0.3 g/dL、1.35±0.3 g/dL，在白天时段分别为1.81±0.3 g/dL、1.59±0.3 g/dL、1.26±0.3 g/dL。该成熟乳组存在统计学差异（P<0.05）。尽管我们观察到在哺乳期的各个阶段氮和蛋白质含量存在差异，但仅在成熟哺乳期妇女群体中，所分析的组分在白天和夜间之间存在显著差异。
