补铁对妊娠早期超重和肥胖妇女肠道微生物群组成的影响总体较小
缺铁在全球很常见，在怀孕期间，随着怀孕进展，由于胎儿铁需求的增加，循环铁水平下降。这通常会导致缺铁，从而增加早产，低出生体重和新生儿死亡的风险。缺铁也影响肠道微生物的组成，并且可导致已知产生短链脂肪酸（SCFA）的细菌物种（包括Roseburia spp.）的减少。
补铁是逆转缺铁的常用策略；然而，口服补充剂中吸收比例通常较低。因此，未吸收的Fe可能到达结肠，由于铁是许多细菌必不可少的营养物质，未吸收的铁有可能改变肠道微生物群的组成。
本研究探讨了妊娠期补充多种维生素铁的剂量对孕早期肠道微生物的影响。
Dietary intake of fat and fibre according to reference values relates to higher gut microbiota richness in overweight pregnant women
British Journal of Nutrition (2018)
DOI：10.1017/S0007114518001149
论文摘要
Fe is an essential nutrient for many bacteria, and Fe supplementation has been reported to affect the composition of the gut microbiota in both Fe-deficient and Fe-replete individuals outside pregnancy. This study examined whether the dose of Fe in pregnancy multivitamin supplements affects the overall composition of the gut microbiota in overweight and obese pregnant women in early pregnancy. Women participating in the SPRING study with a faecal sample obtained at 16 weeks’ gestation were included in this substudy. For each subject, the brand of multivitamin used was recorded. Faecal microbiome composition was assessed by 16S rRNA sequencing and analysed with the QIIME software suite. Dietary intake of Fe was assessed using a FFQ at 16 weeks’ gestation. Women were grouped as receiving low (<60 mg/d, n 94) or high (≥60 mg/d; n 65) Fe supplementation. The median supplementary Fe intake in the low group was 10 (interquartile range (IQR) 5–10) v. 60 (IQR 60–60)mg/d in the high group (P<0·001). Dietary Fe intake did not differ between the groups (10·0 (IQR 7·4–13·3) v. 9·8 (IQR 8·2–13·2) mg/d). Fe supplementation did not significantly affect the composition of the faecal microbiome at any taxonomic level. Network analysis showed that the gut microbiota in the low Fe supplementation group had a higher predominance of SCFA producers. Pregnancy multivitamin Fe content has a minor effect on the overall composition of the gut microbiota of overweight and obese pregnant women at 16 weeks’ gestation.
研究对象：超重和肥胖孕妇（澳大利亚）。
入组标准：参加SPRING研究的超重和肥胖孕妇，有粪便样本；排除补充铁摄入量不确定的妇女。
实验方法：在怀孕16周获取粪便样本（在DNA分离前24小时内），-80℃储存；基线包括空腹血样和临床信息，妊娠期间营养摄入量的详细记录（癌症理事会维多利亚州流行病学研究饮食调查表DQES版本2.0）；妊娠期服用多种维生素和其他食物补充剂，包括品牌和剂量；将妇女分为低补充铁摄入量（LI）0～10mg/d（n=94）组和高补充铁摄入量（HI）大于60mg/d（n=65）组。
检测方法：16S rRNA基因测序
研究结论：
在任何分类学水平上，补铁对粪便微生物群的组成没有显著影响；
网络分析表明，低铁添加组肠道微生物群中SCFA（短链脂肪酸）产生菌的优势度较高，可能有利于维持肠屏障的完整性；
妊娠期复合维生素Fe含量对16周妊娠期超重和肥胖孕妇肠道微生物群的总体组成影响较小。
补充知识点：
SPRING研究：Study of Probiotics IN Gestational diabetes，益生菌预防超重和肥胖妇女妊娠期糖尿病的多中心随机临床试验 [参考文献：Nitert MD, Barrett H, Foxcroft K, et al. (2013) SPRING: an RCT study of probiotics in the prevention of gestational diabetes mellitus in overweight and obese women. BMC Pregnancy Childbirth 13, 50.]
癌症理事会维多利亚州流行病学研究饮食调查表DQES版本2.0： Cancer Council Victoria’s Dietary Questionnaire for Epidemiological Studies DQES version 2.0 [参考文献：Giles GG IP (1996) Dietary Questionnaire for Epidemiological Studies (Version 2). Melbourne: The Cancer Council Victoria.]
Figure 1. Overall composition of the gut microbiota in women with high or low supplementary iron intake. (a) Beta-diversity plot for supplementary iron intake showing diversity of the gut microbiota within the high-iron supplementation group, within the low supplementation group and between the groups. Beta-diversity was assessed by Anosim and was found to be significantly different between the groups. (b) Principal component analysis (PCA) plot at the genus level for women with high ( ) and low ( ) supplementary iron intake.
图 1. 补充铁摄入量高或低的妇女肠道微生物群的总体组成。(a)补充铁摄入量的β多样性图，显示高铁补充组、低铁补充组和各组之间的肠道微生物多样性。用Anosim评估了贝塔多样性，发现各组之间有显著差异。(b)补充铁摄入量高( )和低( )的妇女在属水平上的主成分分析(PCA)图。
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