Legacy AI grade · Sources dated 2026-07-25. Not expert reviewed. Coverage is limited to the listed sources. About the new summary workflow
Calcium for Bone Fracture
The evidence on calcium for fracture prevention is genuinely conflicting and population-dependent: it does little or nothing for healthy community-dwelling adults, and any meaningful benefit is largely confined to calcium combined with vitamin D in frail, institutionalized, or low-intake elderly people. For most people, calcium supplements are not a reliable way to prevent fractures.
Why this grade7-layer evidence engine
This is graded weak (C) and flagged as disputed because high-quality trials point in opposite directions depending on who is studied. In free-living older adults the signal is essentially null: a large government-funded meta-analysis (PMID 29279934, n=51,145) found combined calcium plus vitamin D did not lower hip fracture (RR 1.09), and the Women's Health Initiative RCT (PMID 16481635, n=36,282) found no benefit in its main analysis (hip-fracture HR 0.88, not significant), with benefit emerging only among adherent women and those 60 and older.
The countervailing evidence comes mostly from higher-risk groups and combined supplementation. The landmark Chapuy trial (PMID 1331788) cut hip fractures ~43% in institutionalized, low-intake, vitamin-D-deficient elderly women, and meta-analyses report reductions for calcium plus vitamin D (PMID 31860103: hip RR 0.84; PMID 26510847: hip RR 0.70). Notably, the largest benefit (PMID 26510847) is industry/advocacy-funded, calcium alone shows the weakest effect, and WHI also recorded more kidney stones (HR 1.17).
Regulators and clinics echo this restraint. The FDA permits only a qualified claim that adequate calcium with vitamin D 'may reduce the risk of osteoporosis,' the UK NHS says a balanced diet should supply calcium and warns high doses can cause stomach upset, the WHO recommends supplementation only for low-intake pregnant women, and Mayo Clinic notes supplements have a 'modest and limited' effect, favoring diet and exercise. Together these put calcium at weak, conditional evidence rather than a general fracture-prevention recommendation.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.485
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 1 個 hard + 1 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status