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Head-to-head evidence comparison — which supplement is right for you?
Calcium wins 3 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
Mostly mechanism / observational
Top outcomes
Shared outcomes (1)
Outcomes where both Calcium and Letrozole 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
Indication-specific and clinician-directed. Ovulation induction: 2.5-7.5 mg once daily for 5 days early in the cycle (typically days 3-7). Breast cancer: 2.5 mg once daily continuously. Off-label male use mirrors 2.5 mg once to a few times weekly (NOT daily) titrated to testosterone/estradiol — a prescription drug, not an approved supplement regimen.
any
Oral letrozole 2.5 mg tablet (Femara / generic)
6-24 months
12-36 months
Throughout pregnancy
Within days of starting
Per cycle (days 3-7 dosing)
Weeks to months
Months to years
Months to years
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
Letrozole versus clomiphene for infertility in the polycystic ovary syndrome.
The New England journal of medicine (2014) · Rct · n=750
Double-blind multicenter RCT of 750 women with PCOS randomized to letrozole or clomiphene for up to five cycles, primary outcome live birth
Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome.
Cochrane Database of Systematic Reviews (2022) · Meta analysis
Cochrane systematic review of 41 RCTs (6522 women); letrozole was used in all trials
Aromatase inhibitors (letrozole) for subfertile women with polycystic ovary syndrome.
Cochrane Database of Systematic Reviews (2018) · Meta analysis
Earlier Cochrane systematic review including 42 RCTs (7935 women); letrozole was used in all studies
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.
AI-estimated from published studies. Interpret as directional guidance.
Calcium has a higher evidence score (8/10 vs 5/10) and wins in 3 of 3 categories.
No known interactions between Calcium and Letrozole have been documented in our database. However, always consult a healthcare provider before combining supplements.