Supplementary Material for: Effect of Enteral Vitamin A on Fecal Calprotectin in Extremely Preterm Infants: A Nested Prospective Observational Study

<b><i>Background:</i></b> Vitamin A has anti-inflammatory and immune-modulating properties. We aimed to assess whether enteral water-soluble vitamin A supplementation in extremely preterm infants decreases fecal calprotectin, a marker of intestinal inflammation. <b><i>Methods:</i></b> This was a prospective observational study nested in a randomized, double-blind, placebo-controlled clinical trial investigating enteral vitamin A (5,000 IU/day) for reducing the severity of bronchopulmonary dysplasia (BPD) in extremely preterm infants. Fecal calprotectin levels were measured using enzyme-linked immunosorbent assay after 28 days of Vitamin A or placebo supplementation. <b><i>Results:</i></b> Fecal calprotectin was measured in 66 infants (Vitamin A: 33, Placebo: 33). The mean (standard deviation) gestational age (25.5 [1.55] vs. 25.8 [1.48]; <i>p</i> = 0.341) (week), birth weight (810 [200] vs. 877 [251]; <i>p</i> = 0.240) (gram), and factors influencing fecal calprotectin levels were comparable between the vitamin A versus placebo group infants. All infants were exclusively fed with mother’s or donor’s human breast milk if mother’s milk was unavailable using a standardized feeding regimen and received prophylactic probiotic supplementation. Fecal calprotectin levels (median; 25th–75th centiles) (micrograms/gram of feces) were not significantly different between vitamin A (152; 97–212) and placebo groups (179; 91–313) (<i>p</i> = 0.195). Two infants in the vitamin A group developed definite necrotizing enterocolitis compared to none in the placebo group. Incidence of BPD at 36 weeks postmenstrual age was similar between the groups (vitamin A: 18/33, placebo: 13/33, <i>p</i> = 0.218). <b><i>Conclusion:</i></b> Enteral supplementation with water-soluble vitamin A did not affect fecal calprotectin levels in extremely preterm infants. Studies with a larger sample size are required to confirm the findings.

**背景：** 维生素A具有抗炎及免疫调节特性。本研究旨在评估极早早产儿经肠内给予水溶性维生素A补充剂是否可降低粪便钙卫蛋白(fecal calprotectin)——一种肠道炎症标志物——的水平。
**方法：** 本研究为一项嵌套于随机双盲安慰剂对照临床试验的前瞻性观察研究，该临床试验旨在探究肠内给予维生素A（5000 IU/天）以降低极早早产儿支气管肺发育不良(BPD)的严重程度。在补充维生素A或安慰剂28天后，采用酶联免疫吸附试验(enzyme-linked immunosorbent assay)检测粪便钙卫蛋白水平。
**结果：** 本研究共纳入66名婴儿（维生素A组33名，安慰剂组33名）。两组婴儿的胎龄（均值[标准差]：25.5[1.55] vs. 25.8[1.48]；p=0.341，单位：周）、出生体重（810[200] vs. 877[251]；p=0.240，单位：克）及影响粪便钙卫蛋白水平的相关因素均具有可比性。所有婴儿均采用标准化喂养方案，若母亲无法提供母乳，则纯喂养母亲母乳或供体人乳，并接受预防性益生菌补充。两组的粪便钙卫蛋白水平[中位数；25th~75th百分位数]（单位：微克/克粪便）无显著差异：维生素A组为152；97~212，安慰剂组为179；91~313（p=0.195）。维生素A组有2名婴儿确诊为坏死性小肠结肠炎(necrotizing enterocolitis)，而安慰剂组无此类病例。两组在妊娠后36周胎龄时的支气管肺发育不良发生率相似（维生素A组：18/33，安慰剂组：13/33，p=0.218）。
**结论：** 经肠内给予水溶性维生素A补充剂并未对极早早产儿的粪便钙卫蛋白水平产生影响。未来需开展更大样本量的研究以验证本研究结果。