People mainly take Iron Supplementation for energy, anxiety, performance. Based on 4 first-hand reports and 243 meta-analyses & systematic reviews in the medical literature. Ranked #686 of 2,750 overall.
Of reports that state an outcome, 75% are positive.
Of the people who reported each effect, the share who said it got better.
Systematic reviews and meta-analyses from PubMed, with their published conclusions.
3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.
Conclusion: High-level ID female athletes experience a negative impact on endurance performance, which can be improved by supplementing with ∼100 mg of elemental iron per day or bi-daily. The decrements in other performance parameters characterizing a range of sports coincide with the severity of iron deficiency.
PubMed 39536912 ↗Conclusion: Iron supplementation has a significant positive effect on the intelligence, attention and concentration, and the memory of school-age children but there was no evidence on the effect of iron supplementation on their school achievement.
PubMed 37368919 ↗Conclusion: Low-dose iron supplementation (<5 mg/kg/day) combined with treatment durations of either less than 3 months or more than 6 months, is optimal for improving Hb levels in children and adolescents with IDA. Tailoring treatment based on baseline Hb levels and anaemia severity is essential. These findings provide evidence to support updated guidelines on iron supplementation in paediatric and adolescent populations and inform national anaemia management programmes.
PubMed 39951396 ↗Conclusion: Subgroup analyses confirmed consistent results for ID-only groups, youth, and menstruating adults, though supplementation effects were absent when excluding ID participants. This suggests that, before anemia emerges, ID may impact brain function, potentially requiring identification and treatment.
PubMed 40945632 ↗As stated by users — not a recommendation. Follow the label or your doctor.
How often each side effect came up across all reports.
Verbatim quotes, shortened only — each links to the original discussion.
“Correcting your thyroid and increasing your ferritin will both make a world of difference, both cause significant fatigue.”
“3 months of iron supplementation and daily physical therapy exercises have saved me.”
“Doctors love to tell people to supplement iron to 'fix' iron deficiency anemia, but it's really difficult to succeed at it.”
“My tremors, tachycardia, and physical agitation when anxious only disappeared once it reached around 160 ng/mL.”
User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 3, 2026. How we rate