Geissler P W, Mwaniki D L, Thiong'o F, Michaelsen K F, Friis H
Danish Bilharziasis Laboratory, Charlottenlund, Denmark.
Trop Med Int Health. 1998 Jul;3(7):529-34. doi: 10.1046/j.1365-3156.1998.00272.x.
As part of a cross-sectional study among 156 primary school children (median age 13 years, range 10-18) in Western Kenya, geophagy was assessed through interviews. 114 (73.1%) of these children reported eating soil daily. Haemoglobin levels were determined in all 156 children and serum ferritin concentrations in 135. The mean haemoglobin (Hb) concentration was 12.7 g/dl, and median ferritin concentration 27.2 microg/l. Both the proportion of anaemic (Hb < 11.0 g/dl) and of iron-depleted (ferritin < 12 microg/l) children was significantly higher among the geophageous children than among the nongeophageous (9.6% vs. 0% anaemia; P = 0.037; 18.4% vs. 5.4% iron depletion; P = 0.046). Serum ferritin and haemoglobin concentrations were not correlated (r = 0. 13 5; P = 0. 100). Multiple regression analysis showed that geophagy, hookworm eggs per gram faeces and malaria parasite counts per microl blood were independent predictors of serum ferritin, when controlling for other helminth infections, age and sex, and socio-economic and educational background of the children's families and family size (y = 36.038-11.247(geophagy) -- 0.010(hookworm epg) + 0.001(malaria parasite counts); R2 = 0.17). Multiple regression analysis with haemoglobin as dependent variable and the same independent variables did not reveal any significant predictors. Analysis of the soil eaten by the children revealed a mean HCl-extractable iron content of 168.9 mg/kg (SD 44.9). Based on the data on the amounts eaten daily and this mean iron content, soil could provide on average 4.7 mg iron to a geophageous child (interquartile range 2.1-7.1 mg), which is equivalent to 32% of the Recommended Nutrient Intake (RNI) for girls (interquartile range 14-48%) or 42% of the RNI for boys (interquartile range 19-63%). Iron depletion and anaemia are associated with geophagy, but only serum ferritin concentrations were shown to be dependent upon geophagy in the regression model. From the cross-sectional data no inference about causality can be made. To clarify the possible causal relationships involved, longitudinal studies and iron-supplementation intervention studies are needed.
作为对肯尼亚西部156名小学生（年龄中位数13岁，范围10 - 18岁）开展的一项横断面研究的一部分，通过访谈对食土癖进行了评估。这些儿童中有114名（73.1%）报告每天吃土。对所有156名儿童测定了血红蛋白水平，对135名儿童测定了血清铁蛋白浓度。平均血红蛋白（Hb）浓度为12.7 g/dl，铁蛋白浓度中位数为27.2 μg/l。食土儿童中贫血（Hb < 11.0 g/dl）和缺铁（铁蛋白 < 12 μg/l）儿童的比例均显著高于非食土儿童（贫血：9.6% 对0%；P = 0.037；缺铁：18.4% 对5.4%；P = 0.046）。血清铁蛋白和血红蛋白浓度无相关性（r = 0.135；P = 0.100）。多元回归分析表明，在控制其他蠕虫感染、年龄、性别以及儿童家庭的社会经济和教育背景及家庭规模后，食土癖、每克粪便中的钩虫卵数和每微升血液中的疟原虫计数是血清铁蛋白的独立预测因素（y = 36.038 - 11.247（食土癖） - 0.010（钩虫卵数/克） + 0.001（疟原虫计数）；R2 = 0.17）。以血红蛋白为因变量、相同自变量进行的多元回归分析未发现任何显著的预测因素。对儿童所吃土壤的分析显示，盐酸可提取铁含量平均为168.9 mg/kg（标准差44.9）。根据每日食用量数据和该平均铁含量，土壤可为食土儿童平均提供4.7 mg铁（四分位距2.1 - 7.1 mg），这相当于女孩推荐营养素摄入量（RNI）的32%（四分位距14 - 48%）或男孩RNI的42%（四分位距19 - 63%）。缺铁和贫血与食土癖有关，但在回归模型中仅血清铁蛋白浓度显示依赖于食土癖。从横断面数据无法推断因果关系。为阐明其中可能的因果关系，需要开展纵向研究和铁补充干预研究。
