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Head-to-head evidence comparison — which supplement is right for you?
Iron vs Zinc: Iron has the stronger overall evidence (9 vs 8.5/10); take care combining them — there's a flagged interaction. Take the 60-second quiz for a pick tailored to your goals.
Iron wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
6 of 8 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
13 of 15 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (2)
Outcomes where both Iron and Zinc have evidence — compare verdict strength side-by-side.
18-40mg elemental iron for deficiency (varies by severity) (a typical label dose, not the dose used in the cited trials, which used 60 to 120 mg a day)
On empty stomach if tolerated, Away from tea, coffee, dairy
Ferrous bisglycinate (gentle, well-absorbed) or iron protein succinylate
15-25mg daily (a typical label dose, not the dose used in the cited trials, which used about 30 mg a day)
With meals
Zinc picolinate or zinc citrate
and 6 more not shown
and 4 more not shown
Mutual inhibition of absorption - iron reduces zinc, zinc reduces iron
Separate by 2+ hours. Take zinc between meals, iron with vitamin C.
2-4 weeks
4-8 weeks
4-12 weeks
2-4 weeks
2-4 weeks
4-8 weeks
Immediate
Daily oral iron supplementation during pregnancy
The Cochrane database of systematic reviews (2024) · Meta analysis · n=48971
There is probably little to no difference in maternal death (2 versus 4 events, RR 0.57, 95% CI 0.12 to 2.69; 3 trials, 14,060 women; moderate-certainty evidence).
The Prevalence of Anemia among Pregnant Women in China: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=1376204
The results showed that the prevalence of anemia, ID, and IDA among pregnant women in China were 30.7% (95% CI: 26.6%, 34.7%), 45.6% (95% CI: 37.0%, 54.2%), and 17.3% (95% CI: 13.9%, 20.7%), respectively.
Treatment for women with postpartum iron deficiency anaemia
The Cochrane database of systematic reviews (2024) · Meta analysis · n=4558
Intravenous iron versus oral iron supplementation The evidence is very uncertain about the effect of intravenous iron on mortality (risk ratio (RR) 2.95, 95% confidence interval (CI) 0.12 to 71.96; P = 0.51; I² = not applicable; 3 RCTs; 1 event; 572 women; very low-certainty evidence).
Efficacy of Zinc Supplementation in the Management of Primary Dysmenorrhea: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=739
Zinc supplementation significantly reduced pain severity compared to placebo (Hedges's g = -1.541; 95% CI: -2.268 to -0.814; p < 0.001), representing a clinically meaningful reduction in pain.
Effects of Daily Zinc Alone or in Combination with Other Nutrient Supplements on the Risk of Malaria Parasitaemia: A Systematic Review and Meta-Analysis of Randomised Controlled Trials
Nutrients (2023) · Meta analysis · n=1339
The effect sizes, represented as risk ratios (RRs) with 95% confidence intervals (CIs), were standardised by transforming them into log RRs and then pooling them using a fixed-effects or random-effects model depending on the heterogeneity across studies.
Prevalence of Zinc Deficiency in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis
Nutrients (2022) · Meta analysis · n=806
Pooled analyses by the IBD subgroup showed a total population of 1677 with CD, for an overall mean zinc deficiency prevalence of 54% and 95% confidence intervals (CI) ranging from 0.51 to 0.56, versus 41% (95%CI 0.38-0.45) in the UC population (n = 806).
Iron has a higher evidence score (9/10 vs 8.5/10) and wins in 2 of 3 categories.
For support immune system, Zinc has a higher relevance score (90 vs 20).
Caution: Mutual inhibition of absorption - iron reduces zinc, zinc reduces iron Separate by 2+ hours. Take zinc between meals, iron with vitamin C. Always consult a healthcare provider before combining these supplements.
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The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.