Effects of dietary polyphenol supplementation on iron status and erythropoiesis: a systematic review and meta-analysis of randomized controlled trials

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#anemia-iron-deficiency #dietary-supplements #erythropoiesis #humans #iron

Effects of dietary polyphenol supplementation on iron status and erythropoiesis: a systematic review and meta-analysis of randomized controlled trials

Xu et al., 2021 | Am J Clin Nutr | Meta Analysis

Citation

Xu Teng, Zhang Xu, ... An Peng. Effects of dietary polyphenol supplementation on iron status and erythropoiesis: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2021-Aug-02;114(2):780-793. doi:10.1093/ajcn/nqab068

Abstract

BACKGROUND: The iron-chelating activities of polyphenols raise concern whether there is a risk of iron deficiency or anemia induced by polyphenol supplementation. Results from clinical trials regarding the effects of polyphenol supplementation on iron status and erythropoiesis are inconclusive. OBJECTIVE: We performed a systematic review and meta-analysis of randomized controlled trials to determine the effects of polyphenol supplementation on iron status and erythropoiesis. METHODS: Published articles were searched between May 1988 and 7 December, 2020. Finally, we identified 34 randomized controlled trials. Random-effects meta-analyses were performed to obtain the weighted mean difference of serum iron (SI), transferrin saturation (TS), ferritin, and hemoglobin concentration. Funnel plots and Egger's test were used to determine the risk of bias. The robustness of the effect sizes was examined by sensitivity analysis. RESULTS: Polyphenol supplementation had an inhibitory effect on the SI concentration (-13.72 μg/dL; 95% CI: -20.74, -6.71) and TS (-3.10%; 95% CI: -4.93, -1.27), with no effect on ferritin (-9.34 ng/mL; 95% CI: -28.55, 9.87). Polyphenols increased the hemoglobin concentration (8.53 g/L; 95% CI: 3.33, 13.73). In healthy participants, polyphenol reduced the TS (-3.83%; 95% CI: -7.47, -0.19) and increased the hemoglobin concentration (12.87 g/L; 95% CI: 1.61, 24.14). Similarly, polyphenol reduced the SI concentration (-8.60 μg/dL; 95% CI: -16.10, -1.10) and increased the hemoglobin concentration (8.50 g/L; 95% CI: 0.86, 16.15) in patients with metabolic diseases. In patients with β-thalassemia, polyphenol decreased the SI concentration (-23.19 μg/dL; 95% CI: -35.84, -10.55), TS (-3.23%; 95% CI: -5.54, -0.91), and ferritin concentration (-223.62 ng/mL; 95% CI: -359.32, -87.91), but had no effect on the hemoglobin concentration. CONCLUSION: Healthy individuals and patients with metabolic diseases may benefit from the positive impact of polyphenols on erythropoiesis. Patients with β-thalassemia may benefit from the effect of polyphenols on reducing SI. This trial was registered at PROSPERO (International prospective register of systematic reviews) as CRD42020161983.

Key Findings

Polyphenol supplementation had an inhibitory effect on the SI concentration (-13.72 μg/dL; 95% CI: -20.74, -6.71) and TS (-3.10%; 95% CI: -4.93, -1.27), with no effect on ferritin (-9.34 ng/mL; 95% CI: -28.55, 9.87). Polyphenols increased the hemoglobin concentration (8.53 g/L; 95% CI: 3.33, 13.73). In healthy participants, polyphenol reduced the TS (-3.83%; 95% CI: -7.47, -0.19) and increased the hemoglobin concentration (12.87 g/L; 95% CI: 1.61, 24.14). Similarly, polyphenol reduced the SI con

Outcomes Measured

  • Requires manual extraction

Population

Field Value
Population healthy participants
Sample Size See abstract
Age Range See abstract
Condition deficiency

MeSH Terms

  • Anemia, Iron-Deficiency
  • Dietary Supplements
  • Erythropoiesis
  • Humans
  • Iron
  • Iron Chelating Agents
  • Polyphenols

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Research Support, Non-U.S. Gov't, Systematic Review
  • Vertical: iron

Provenance

Source extracted via PubMed E-utilities API on 2026-04-09