Hernandez-Avila Mauricio, Gonzalez-Cossio Teresa, Hernandez-Avila Juan E, Romieu Isabelle, Peterson Karen E, Aro Antonio, Palazuelos Eduardo, Hu Howard
Centro de Investigación en Salud Poblacional, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
Epidemiology. 2003 Mar;14(2):206-12. doi: 10.1097/01.EDE.0000038520.66094.34.
Pregnancy and breastfeeding mobilize lead stored in bone, which may be a hazard for the fetus and infant. We tested the hypothesis that in lactating women a dietary calcium supplement will lower blood lead levels.
Between 1994 and 1995 we conducted a randomized trial among women in Mexico City. Lactating women (N = 617; mean age = 24 years; mean blood lead level = 8.5 ug/dL) were randomly assigned to receive either calcium carbonate (1200 mg of elemental calcium daily) or placebo in a double-blind trial. Blood samples were obtained at baseline, and 3 and 6 months after the trial began. Blood lead was determined by graphite furnace atomic absorption spectroscopy. Bone lead was measured at baseline with a 109cd K x-ray fluorescence instrument. The primary endpoint was change in maternal blood lead level, which was analyzed in relation to supplement use and other covariates by multivariate generalized linear models for longitudinal observations.
An intention-to-treat analysis showed that women randomized to the calcium supplements experienced a small decline in blood lead levels (overall reduction of 0.29 ug/dL; 95% confidence interval = -0.85 to 0.26). The effect was more apparent among women who were compliant with supplement use and had high bone lead levels (patella bone lead > or =5 microg/gm bone). Among this subgroup, supplement use was associated with an estimated reduction in mean blood lead of 1.16 ug/dL (95% confidence interval = -2.08 to -0.23), an overall reduction of 16.4%.
Among lactating women with relatively high lead burden, calcium supplementation was associated with a modest reduction in blood lead levels.
怀孕和哺乳会调动储存在骨骼中的铅，这可能对胎儿和婴儿构成危害。我们检验了这样一个假设，即哺乳期妇女补充膳食钙会降低血铅水平。
1994年至1995年期间，我们在墨西哥城的妇女中进行了一项随机试验。哺乳期妇女（N = 617；平均年龄 = 24岁；平均血铅水平 = 8.5微克/分升）在一项双盲试验中被随机分配接受碳酸钙（每日1200毫克元素钙）或安慰剂。在基线时以及试验开始后3个月和6个月采集血样。血铅通过石墨炉原子吸收光谱法测定。在基线时用109镉K X射线荧光仪器测量骨铅。主要终点是母亲血铅水平的变化，通过多变量广义线性模型对纵向观察结果进行分析，以确定补充剂使用情况和其他协变量与血铅水平变化的关系。
意向性分析表明，随机接受钙补充剂的妇女血铅水平略有下降（总体下降0.29微克/分升；95%置信区间 = -0.85至0.26）。在依从补充剂使用且骨铅水平高（髌骨骨铅≥5微克/克骨）的妇女中，这种效果更为明显。在这个亚组中，补充剂的使用与平均血铅估计降低1.16微克/分升（95%置信区间 = -2.08至 -0.23）相关，总体降低16.4%。
在铅负荷相对较高的哺乳期妇女中，补钙与血铅水平适度降低有关。
