Plasma zinc concentrations (PZC) have been shown to significantly increase during zinc supplementation. This study investigated the effects of daily preventive zinc supplementation on hair and nail zinc concentrations compared with a control group. In a randomized controlled trial, 6- to 23-month-old children (n = 3407) in Lao PDR were randomly assigned to one of four groups and followed for ~ 36 weeks: daily preventive zinc dispersible tablet (7 mg/d; PZ), daily micronutrient powder (10 mg zinc/d; MNP), therapeutic zinc supplements for diarrhea treatment (20 mg/d for 10 days; TZ), or daily placebo powder (Control). Plasma, hair, and nail zinc concentrations were assessed in a sub-sample of participants (n = 457) at baseline and endline. At baseline, 75% of children had low PZC (< 65 μg/dL). At endline, geometric mean (95% CI) PZC were greater in the PZ and MNP groups compared with the TZ and control groups (P < 0.01), but hair zinc concentrations did not differ among groups (P = 0.99). Nail zinc concentrations were marginally higher in the PZ (115.8 (111.6, 119.9) μg/g) and the MNP (117.8 (113.3, 122.3) μg/g) groups than in the TZ group (110.4 (106.0, 114.8) μg/g; P = 0.055) at endline. This study does not support the use of hair zinc as a biomarker of zinc exposure in young children. However, it provides some evidence that zinc concentrations in nails may respond to supplemental zinc interventions and supports the need for collecting additional data on this emerging biomarker.

中文翻译：

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老挝幼童两种不同形式的预防性锌补充剂对血浆和指甲锌浓度有积极反应，但头发锌浓度则不然：一项随机对照试验。

补锌期间血浆锌浓度 (PZC) 显着增加。这项研究调查了与对照组相比，每日预防性补充锌对头发和指甲锌浓度的影响。在一项随机对照试验中，老挝人民民主共和国 6 至 23 个月大的儿童 (n = 3407) 被随机分配到四组中的一组，并随访约 36 周：每日预防性锌分散片（7 毫克/天；PZ） ）、每日微量营养素粉（10 毫克锌/天；MNP）、治疗腹泻的治疗性锌补充剂（20 毫克/天，持续 10 天；TZ）或每日安慰剂粉（对照）。在基线和终点时对参与者子样本（n = 457）的血浆、头发和指甲锌浓度进行了评估。基线时，75% 的儿童 PZC 较低（< 65 μg/dL）。在终点时，与 TZ 组和对照组相比，PZ 组和 MNP 组的 PZC 几何平均值 (95% CI) 更高 (P < 0.01)，但各组之间的毛发锌浓度没有差异 (P = 0.99)。PZ 组（115.8（111.6，119.9）μg/g）和 MNP（117.8（113.3，122.3）μg/g）组的指甲锌浓度略高于 TZ 组（110.4（106.0，114.8）μg/g） ; P = 0.055) 在终点线。这项研究不支持使用头发中的锌作为幼儿锌暴露的生物标志物。然而，它提供了一些证据表明指甲中的锌浓度可能会对补充锌干预措施产生反应，并支持收集有关这一新兴生物标志物的额外数据的必要性。