SynthesisNutrition journal2020
The effect of vitamin D supplementation on hemoglobin concentration: a systematic review and meta-analysis.
Synthesis in Nutrition journal, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. Cited by 29 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
29 citing papers in PubMed, 1 synthesis or guideline pooled it, 53 citations in OpenAlex.
- Nutrition-specific interventions for preventing and controlling anaemia throughout the life cycle: an overview of systematic reviews.The Cochrane database of systematic reviews · 2021Pooled it
- The effect of high-dose vitamin D supplementation on hepcidin-25 and erythropoiesis in patients with chronic kidney disease.BMC nephrology · 2023Trial
- Association of Serum 1,25-Dihydroxyvitamin D Levels with Erythropoietin Resistance Index-Based Relative Erythropoiesis-Stimulating Agent Hyporesponsiveness in Pre-Dialysis Chronic Kidney Disease.International journal of molecular sciences · 2026Article
- Article
- Treatment of Hypovitaminosis D Is Associated with Improvement in Anemia of Inflammation in Patients with Decompensated Cirrhosis.Medical sciences (Basel, Switzerland) · 2026Article
- Vitamin A, Vitamin D, Iron, and Zinc in Relation to Anemia Risk: Observational Evidence and Mendelian Randomization.Nutrients · 2025Observational
- Influential factors and predictive model of anemia in hospitalized elderly patients.Scientific reports · 2025Article
- The Interplay Between Vitamin D Deficiency, Iron Status, and Anemia Risk in Moroccan Women of Reproductive Age: A Cross-Sectional Analysis.Epidemiologia (Basel, Switzerland) · 2024Article
- Multidisciplinary approaches to study anaemia with special mention on aplastic anaemia (Review).International journal of molecular medicine · 2024Review
- Fibroblast growth-factor 23 and vitamin D are associated with iron deficiency and anemia in children with chronic kidney disease.Pediatric nephrology (Berlin, Germany) · 2023Article
- Review
- Associations of Dietary Patterns and Vitamin D Levels with Iron Status in Pregnant Women: A Cross-Sectional Study in Taiwan.Nutrients · 2023Article
- Physiological and Pathological Functions of Neuronal Hemoglobin: A Key Underappreciated Protein in Parkinson's Disease.International journal of molecular sciences · 2022Review
- Article
- Vitamin D food fortification in European countries: the underused potential to prevent cancer deaths.European journal of epidemiology · 2022Review
- Postharvest Ultraviolet Radiation in Fruit and Vegetables: Applications and Factors Modulating Its Efficacy on Bioactive Compounds and Microbial Growth.Foods (Basel, Switzerland) · 2022Review
- Hashimoto's thyroiditis, iron, and vitamin D deficiency among Egyptian female patients: associations and possible causalities.Hormones (Athens, Greece) · 2021Article
- Potential of Vitamin D Food Fortification in Prevention of Cancer Deaths-A Modeling Study.Nutrients · 2021Article
- Effects of Parenteral Vitamin D3 Supplementation on Hematological Parameters of Healthy Holstein Bulls.Archives of Razi Institute · 2021Article
- Etiology of Anemia in Older Mexican Adults: The Role of Hepcidin, Vitamin A and Vitamin D.Nutrients · 2021Article
Corrections and comments
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- Erratum issued
Authors and funding
5 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
aimsThe purpose of this review was to investigate the effect of vitamin D supplements on hemoglobin concentration in subjects aged 17.5-68 years old; using randomized controlled trials (RCTs).
methodsRelevant RCT studies were identified from January 2000 to January 2019 by using MeSH terms in PubMed, Embase, Cochrane Library, Clinical trials, Scopus databases and gray literature. The studies were reviewed systematically, and quality assessments were evaluated by the guidelines of the Cochrane risk of bias. The effect of vitamin D supplements (n = 14) on hemoglobin concentration was considered as primary outcome, while its effects on the levels of ferritin, transferrin saturation and iron status were derived as secondary outcomes. In total, 1385 subjects with age range of 17.5 to 68 years old were examined for 3 h to 6 months; Mean (standard deviation) or median interquartile changes in the hemoglobin concentration in each treatment group was recorded for meta-analysis.
resultsFourteen RCTs met the inclusion criteria. Current study findings propose that vitamin D supplementation leads to a non-significant reduction in hemoglobin levels in subjects (17.5-68 years old) [std. mean difference (SMD): 0.01; 95% CI: - 0.28, 0.29; P = 0.95], also it has no significant effect on ferritin concentrations [std. mean difference (SMD): -0.01; 95% CI: [- 0.20, 0.18; P = 0.91]. However, vitamin D supplementation demonstrated positive effects on transferrin saturation [mean difference (MD): 1.54; 95% CI: 0.31, 2.76; P = 0.01] and iron status [std. mean difference (SMD): 0.24; 95% CI: - 0.09, 0.39; P = 0.002].
conclusionCurrent review concluded that supplementation with vitamin D had no significant effect on hemoglobin and ferritin levels while positive effects on transferrin saturation and iron status were observed. Further clinical studies are required to determine the actual effect of this intervention on hemoglobin levels.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.