Background

Iron deficiency in athletes is initially treated with a nutritional intervention. If negative iron balance persists, oral iron supplementation (OIS) can be used. Despite the recent proposal for a refinement of treatment strategies for iron-deficient athletes, there is no general consensus regarding the actual efficiency, dosage, or optimal regimen of OIS.

Objective

The aim of this meta-analysis was to evaluate to what extent OIS affects blood iron parameters and physical performance in healthy adult athletes.

Methods

PubMed, Web of Science, PEDro, CINAHL, SPORTDiscus, and Cochrane were searched from inception to 2 November 2022. Articles were eligible if they satisfied the following criteria: recruited subjects were healthy, adult and physically active individuals, who used exclusively OIS, irrespective of sex and sports discipline. Exclusion criteria: simultaneous supplementation with iron and any other micronutrient(s), intravenous iron supplementation or recent exposure to altitude acclimatisation. The methodological quality of included studies was assessed with the PEDro scale, the completeness of intervention reporting with the TIDieR scale, while the GRADE scale was used for quality of evidence synthesis. The present study was prospectively registered in PROSPERO online registry (ID: CRD42022330230).

Results

From 638 articles identified through the search, 13 studies (n = 449) were included in the quantitative synthesis. When compared to the control group, the results demonstrated that OIS increases serum ferritin (standardized mean difference (SMD) = 1.27, 95% CI 0.44–2.10, p = 0.006), whereas blood haemoglobin (SMD = 1.31, 95% CI − 0.29 to 2.93, p = 0.099), serum transferrin receptor concentration (SMD = − 0.74, 95% CI − 1.89 to 0.41, p = 0.133), and transferrin saturation (SMD = 0.69, 95% CI − 0.84 to 2.22, p = 0.330) remained unaltered. Following OIS, a trend of small positive effect on VO_2max (SMD = 0.49, 95% CI − 0.09 to 1.07, p = 0.086) was observed in young healthy athletes. The quality of evidence for all outcomes ranged from moderate to low.

Conclusions

Increase in serum ferritin concentration after OIS was evident in subjects with initial pre-supplementation serum ferritin concentration ≤ 12 µg/l, while only minimal, if any effect, was observed in subjects with higher pre-supplementation serum ferritin concentration. The doses of OIS, that induced a beneficial effect on hematological parameters differed from 16 to 100 mg of elementary iron daily, over the period between 6 and 8 weeks. Shorter supplementation protocols have been shown to be ineffective.

中文翻译：

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口服铁补充剂对运动员血铁状态的影响：随机对照试验的系统回顾、荟萃分析和荟萃回归

背景

运动员缺铁首先通过营养干预进行治疗。如果铁负平衡持续存在，可以使用口服铁补充剂（OIS）。尽管最近提出了针对缺铁运动员改进治疗策略的建议，但关于 OIS 的实际效率、剂量或最佳方案尚未达成普遍共识。

客观的

本荟萃分析的目的是评估 OIS 在多大程度上影响健康成年运动员的血铁参数和身体表现。

方法

PubMed、Web of Science、PEDro、CINAHL、SPORTDiscus 和 Cochrane 的检索时间从开始到 2022 年 11 月 2 日。如果文章满足以下标准，则符合资格：招募的受试者是健康、成年和身体活跃的个体，他们只使用 OIS，无论如何性和体育纪律。排除标准：同时补充铁和任何其他微量营养素、静脉注射铁剂或最近经历高原适应。纳入研究的方法学质量采用 PEDro 量表进行评估，干预报告的完整性采用 TIDieR 量表进行评估，而 GRADE 量表则用于证据合成的质量。本研究前瞻性地在 PROSPERO 在线注册中心注册（ID：CRD42022330230）。

结果

从通过检索确定的 638 篇文章中， 定量综合中纳入了13 项研究 ( n = 449)。与对照组相比，结果表明，OIS 增加了血清铁蛋白（标准化均数差 (SMD) = 1.27，95% CI 0.44–2.10，p  = 0.006），而血液中的血红蛋白（SMD = 1.31，95% CI − 0.29）至 2.93，p  = 0.099）、血清转铁蛋白受体浓度（SMD = − 0.74，95% CI − 1.89 至 0.41，p  = 0.133）和转铁蛋白饱和度（SMD = 0.69，95% CI − 0.84 至 2.22，p  = 0.330） ）保持不变。 OIS 后， 在年轻健康运动员中观察到对V O _2max有较小积极影响的趋势（SMD = 0.49，95% CI - 0.09 至 1.07，p = 0.086）。所有结果的证据质量从中等到低。

结论

在初始补充前血清铁蛋白浓度 ≤ 12 µg/l 的受试者中，OIS 后血清铁蛋白浓度明显增加，而在补充前血清铁蛋白浓度较高的受试者中，即使有影响，也仅观察到很小的影响。在 6 至 8 周的时间内，对血液学参数产生有益影响的 OIS 剂量为每日 16 至 100 毫克元素铁。较短的补充方案已被证明是无效的。