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Head-to-head evidence comparison — which supplement is right for you?
Zinc wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
18 of 20 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
21 of 26 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Calcium and Zinc have evidence — compare verdict strength side-by-side.
1000–1200mg daily (split doses)
Split doses with meals, 500mg with breakfast, 500mg with dinner
Calcium Citrate
15-30mg daily
With meals
Zinc picolinate or zinc citrate
Calcium supplementation reduces zinc absorption by 20-50%
Take zinc between meals, calcium with meals. Separate by 2+ hours.
6-24 months
12-36 months
Throughout pregnancy
Within days of starting
2-4 weeks
2-4 weeks
4-8 weeks
Immediate
Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials.
Food & Function (2020) · Meta analysis · n=12000
Combined calcium and vitamin D significantly improved lumbar spine BMD in postmenopausal women
Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis.
JAMA (2017) · Meta analysis · n=51145
33 trials involving 51,145 participants were analyzed
Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis.
JAMA Network Open (2019) · Meta analysis · n=51419
Meta-analysis of 11 randomized clinical trials with 51,419 participants
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).
Based on meta-analysis of 59 RCTs showing 0.6-1.8% BMD increases. Requires vitamin D co-supplementation for optimal effect. Effectiveness plateaus beyond 1200mg daily.
Based on meta-analyses showing reduced respiratory tract infections and improved immune markers (CD3/CD4). Effects primarily in deficient individuals. Take with food to reduce nausea risk.
AI-estimated from published studies. Interpret as directional guidance.
Zinc has a higher evidence score (8.5/10 vs 8/10) and wins in 2 of 3 categories.
For bone health, Calcium has a higher relevance score (95 vs 70).
Calcium supplementation reduces zinc absorption by 20-50% Take zinc between meals, calcium with meals. Separate by 2+ hours. Consult a healthcare provider for personalized advice.